C Plants and photosynthesis Unit guide - Physicslocker 3/Unit C.pdf · C Plants and photosynthesis Unit guide ... Suggested lesson allocation ... also plan and carry out an investigation
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This unit builds on: 7D Variation and classification and 7C Environment and feeding relationships.
The concepts in this unit are: the role of the leaf in photosynthesis, the importance of photosynthesis to humans and other animals.
This unit leads onto:unit 9D Plants for food and to work in key stage 4 on limiting factors in photosynthesis, energy transferthrough an ecosystem and the mineral requirements of plants.
This unit relates to:7I Energy resources, 8A Food and digestion, 8B Respiration, 8D Ecological relationships, 8F Compoundsand mixtures, 9G Environmental chemistry and 9H Using chemistry.
To make good progress, pupils startingthis unit need to understand:• how organisms are sorted into groups
based on features in common• the basic structure of plants• the conditions that plants need to
grow well• that green plants take in water
through their roots and that the leafplays a part in photosynthesis
• that respiration releases CO2.
Framework yearly teaching objectives – Cells• Describe photosynthesis and the requirement of chlorophyll, light, carbon dioxide and water; know that plant nutrition involves photosynthesis and
other nutrients obtained from the soil; use this to explain:– photosynthesis as a source of biomass; – that these other nutrients, used to produce proteins and other substances, can be supplied by
fertilisers; – how leaves and roots are adapted to their functions; – conditions in which plants grow well.• Distinguish between photosynthesis and respiration in plants, including the use of word equations.
Expectations from the QCA Scheme of Work At the end of this unit …
… most pupils will … … some pupils will not have madeso much progress and will …
… some pupils will haveprogressed further and will …
in terms of scientific enquiry NC Programme of Study Sc1 1a, c, 2b, d, g, i, j, k, l, m
• identify variables relevant to an investigation of photosynthesis andsuggest how these might be controlled
• make observations and measurements using an appropriate technique, anduse measurements to produce a graph
• explain patterns in graphs using scientific knowledge and understanding.
• suggest how to control variablesidentified for them in aninvestigation of photosynthesis
• make appropriate observations andmeasurements and produce a graph.
• relate findings about theproduction of oxygen inphotosynthesis to widerenvironmental issues, e.g.seasonal changes.
in terms of life processes and living things NC Programme of Study Sc2 1e, 2k, 3a, b, c, d, e, 4a, 5a, c
• identify carbon dioxide from the air and water as the raw materials, andlight as the energy source, for photosynthesis
• explain photosynthesis as the source of biomass and representphotosynthesis by a word equation
• describe how leaves are adapted for photosynthesis and how roots areadapted to take in water
• distinguish between photosynthesis and respiration in plants.
• identify carbon dioxide from the airand water as the raw materials forphotosynthesis
• recognise that plants take in waterthrough their roots and thatphotosynthesis takes place inleaves.
• describe how cells in the leafand root are adapted forphotosynthesis and for takingin water
• represent photosynthesis as asymbol equation
• describe the relationshipbetween photosynthesis andrespiration in plants.
Suggested lesson allocation (see individual lesson planning guides)Direct route
C1Hungry plants
C2A food factory
C3Don’t dry up!
C4Using plantbiomass
C5Spot thedifference
Booster 1Focus on cells –From cells to organs
Extra lessons (not in Pupil book)
C1 Hungry plantsExtra lesson forActivity C1a.
Review and assessprogress (distributedappropriately)
MisconceptionsPupils often believe that: plants photosynthesise but do not respire; breathe in carbon dioxide and breathe out oxygen; only respire at night.
Additional informationEmphasise that plants need food for respiration just like animals. Animals and plants are different because animals eat their food, whereas plantsmake theirs.
Health and safety (see activity notes to inform risk assessment)Risk assessments are required for any hazardous activity. In this unit pupils carry out a test for starch in which a flammable liquid is heated. Theyalso plan and carry out an investigation into photosynthesis in pondweed.
Learning objectivesi Green plants use carbon dioxide and water from the environment around the plant to produce glucose and oxygen.ii Understand that photosynthesis is the process of producing biomass.iii Light is needed for photosynthesis.iv Represent photosynthesis by a word and/or symbol equation.
Scientific enquiryv Identify and control for relevant variables in an investigation. (Framework YTO Sc1 9b)vi How ideas about plant growth have changed. (Framework YTO Sc1 9a)
Suggested alternative starter activities (5–10 minutes)
Introduce the unit
Unit map for Plants andphotosynthesis.
Share learning objectives
• Describe what photosynthesis is.• Identify and control for relevant
variables in an investigation. (Sc1)• Explain how ideas about plant
growth have changed. (Sc1)
Word game
Pupils do true/false quiz to reveal priorknowledge aboutphotosynthesis.
Brainstorming (1)
Pupils suggest where aplant gets its food.
Brainstorming (2)
Pupils identify differencesbetween a plant on awindowsill and a plantgrowing normally in themiddle of the room.
Suggested alternative plenary activities (5–10 minutes)
Review learning
Pupils fill in a template‘cooking recipe’ forphotosynthesis.
Sharing responses
Collate results andconclusions from ActivityC1a or C1b aboutphotosynthesis.
Group feedback
In small groups, pupilsdiscuss answers fromActivity C1c.
Word game
In small groups, pupilsprepare four questionsabout the lesson’s contentto ask another group.
Looking ahead
In pairs, pupils suggest howplants get the reactants forphotosynthesis to theirleaves.
Learning outcomes
Most pupils will ...
• identify the sources of raw materials in photosynthesis• explain the term photosynthesis• provide some evidence that plants do not obtain ‘food’
from the soil• write the word equation for photosynthesis• identify variables relevant to an investigation of
photosynthesis and suggest how these might becontrolled.
Some pupils, making less progress will ...
• identify the raw materials forphotosynthesis
• state that plants make their own foodwhen it is daylight
• suggest how to control variablesidentified for them in an investigation ofphotosynthesis.
Some pupils, making more progress will ...
• write the symbol equation forphotosynthesis
• identify that carbon dioxide levels arelower in the daylight because leaves areusing carbon dioxide in photosynthesis.
Teacher-led explanation and questioning OR Pupils workindividually, in pairs or in small groups through the in-textquestions and then onto the end-of-spread questions if time allows.
What do plants need for photosynthesis? Pupils test leaves forstarch to find out if a plant needs light and carbon dioxide forphotosynthesis.
What gas is made in photosynthesis? Pupils identify the gasproduced in photosynthesis.
Gases in the greenhouse Pupils analyse data about gas levels in agreenhouse.
Support animation about photosynthesis, allowing you to remove or introduce ingredients and look at the effect onphotosynthesis.
Learning objectivesi Chlorophyll and light are needed for photosynthesis.ii Leaves are adapted to photosynthesise efficiently.iii How leaf cells are specialised for photosynthesis.
Scientific enquiryiv Make systematic observations with appropriate precision. (Framework YTO Sc1 9d)v Describe patterns in graphs, using scientific knowledge to interpret them. (Framework YTO Sc1 9f)
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Pupils list the products andreactants of photosynthesis.
Share learningobjectives
• Describe why plants needchlorophyll and light tophotosynthesise.
• Explain why leaves aregood at photosynthesis.
• Identify patterns in thedata, and drawconclusions. (Sc1)
Word game
Pupils play Snap! with cardsshowing different cell typesand cards with theirspecialisations, to remindthem of how cells arespecialised to theirfunction.
Brainstorming (1)
In groups, pupils draw aplant cell and label as manyfeatures as they canremember.
Brainstorming (2)
Show pupils a photo of asolar panel and discuss howit is suited to its purpose.Catalyst InteractivePresentations 3
Suggested alternative plenary activities (5–10 minutes)
Review learning
Pelmanism game matchingleaf parts to functions.
Sharing responses
Ask pupils to suggest whatwill happen in Activity C2a.
Group feedback
Pupils share ideas about therole of each part of the leaffrom Activity C2b.
Word game
Word splat to checkprogress on leaf structures.
Looking ahead
Pupils discuss word pairs.
Learning outcomes
Most pupils will ...
• detect the presence of starch in a photosynthesisingleaf and relate it to the presence of chlorophyll
• describe how the leaf is specialised for photosynthesisand identify some differences between leaf cells
• use a range of evidence to investigate the effect oflight intensity on photosynthesis and growth.
Some pupils, making less progress will ...
• describe some ways in which leaf shapeand size can be specialised forphotosynthesis
• describe how to test for starch in leaves• use a simulation to investigate the effect
of light intensity on photosynthesis.
Some pupils, making more progresswill ...
• describe differences between leaf cells,explaining how the palisade cells arespecialised for photosynthesis
• explain how the rate of production ofoxygen varies with light intensity
• use graphs to show how plant growthvaries with time, identifying andexplaining anomalous results.
Suggested alternative main activitiesActivity
Textbook C2
Activity C2a ICT
Activity C2b Practical
Activity C2cCatalyst InteractivePresentations 3
Learningobjectivessee above
i, ii and iii
i, iv and v
i, ii and iii
i, iv and v
Description
Teacher-led explanation and questioning OR Pupils workindividually, in pairs or in small groups through the in-textquestions and then onto the end-of-spread questions if time allows.
When do plants grow fastest? Demonstration using datalogging to compare the growth of seedlings by day and by night.
Looking at leaves Pupils look at pre-prepared leaf slides toreinforce the structure and function of a leaf.
Support animation of bubbling pondweed with variable lightintensity (and other variables for extension students) to investigateeffect of light on photosynthesis.
Approx.timing
20 min
45 min over2 lessons
30 min
25 min
Target group
C H E S
R/G G R S
✔
✔
✔
Key wordspalisade cell, chlorophyll, chloroplasts, stomata, red only: specialised,diffuse
Learning objectivesi Roots are adapted to take in water and nutrients.ii Plants use water in many ways, including photosynthesis.iii Roots need oxygen for respiration.iv Plants need nutrients which are dissolved in water.
Scientific enquiryv Make careful observations and record these in drawings. (Framework YTO Sc1 9e)
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Pupils list five features of aleaf that make it good atphotosynthesis.
Share learningobjectives
• Describe how roots take inwater and nutrients fromthe soil.
• Describe how plants usewater for various reasons.
• Draw biological specimensusing a microscope. (Sc1)
Word game
Pupils play a true/false quizby showing cards.
Problem solving
Show pupils a daffodil thathas been standing in blueink for 24 hours. In pairs,ask pupils to discuss andsuggest one idea for whythe petals have turned blue.
Capture interest
Show pupils photos of aplant that has been under-watered and a plant thathas been over-watered.Catalyst InteractivePresentations 3
Suggested alternative main activitiesActivity
Textbook C3
Activity C3a Practical
Activity C3b Practical
Activity C3cCatalyst InteractivePresentations 3
Learningobjectivessee above
i, ii, iii andiv
i and v
i, ii and iv
i, ii and iv
Description
Teacher-led explanation and questioning OR Pupils work individually,in pairs or in small groups through the in-text questions and thenonto the end-of-spread questions if time allows.
Looking at root hairs Pupils look at pre-prepared slides of root toreinforce their knowledge of structure and function.
Water transport in celery Pupils view coloured water in plant veinsto reinforce their understanding of the structure and function ofveins in plants.
Support simulation to build up pupils’ understanding of the route bywhich water moves from roots to leaves, and by which glucose movesfrom leaves to the other parts of the plant.
Approx.timing
20 min
30 min
20 minover 2 lessons
15 min
Target group
C H E S
R/G G R S
✔
✔
✔
Suggested alternative plenary activities (5–10 minutes)
Review learning
As a class, draw a flowchart of water movement ina plant on the board.
Sharing responses
Collate results andconclusions from Activity C3b.
Group feedback
Share ideas from ActivityC3a about how root hairshelp the plant take in waterand nutrients from the soil.
Word game
Loop game onphotosynthesis to checkprogress.
Looking ahead
As a class, discuss why acarrot root is swollen withstored food, rather thanbeing branched and thin.
Learning outcomes
Most pupils will ...
• explain the functions of water and nutrients in plants• explain how roots are specialised to take in water• describe how a root hair cell is specialised for its
function• in response to a variety of evidence, work out how
water is transported through a plant• use a microscope safely to make careful observations
of root hairs.
Some pupils, making less progress will ...
• describe some of the functions of waterand nutrients in plants
• describe some of the ways in whichroots are specialised to take in water
• use a simulation to describe the routetaken by water and glucose through aplant.
Some pupils, making more progress will ...
• explain how a root hair cell is specialised forits function
• explain why plants in waterlogged soil willdie, even though they have ample water andminerals.
Out-of-lesson learningHomework C3Textbook C3 end-of-spread questionsPupils investigate the ingredients of fertiliser from the Internet, and find out what each component is used for by the plant.
Learning objectivesi Plants store starch.ii New materials made from glucose produced in photosynthesis lead to an increase in biomass.iii Glucose from photosynthesis provides energy for all living processes in the green plant.iv Understand the meaning of the term biomass.
Scientific enquiryv Identify relevant information and use different texts as sources. (Framework YTO Sc1 8d)
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Give pupils the list ofanswers. Ask them to workin pairs to devise questionsfor each of these answers.
Share learningobjectives
• Describe how plants useglucose.
• Describe what biomass is.• Select relevant
information from differentwebsites. (Sc1)
Problem solving
In groups, pupils identifyphotos of a range of storageorgans as fruit, stem, rootor leaf.Catalyst InteractivePresentations 3
Brainstorming
Pupils list five things thatare made of plants in theirhouse.
Word game
Pupils complete thewordsearch to findcomponents of a plant’sbiomass (protein, cellulose,etc.).
Suggested alternative main activitiesActivity
Textbook C4
Activity C4a ICT
Activity C4b Paper
Activity C4cCatalyst InteractivePresentations 3
Learningobjectivessee above
i, ii, iii and iv
ii, iii, iv andv
i, ii, iii andiv
i and ii
Description
Teacher-led explanation and questioning OR Pupils work individually,in pairs or in small groups through the in-text questions and thenonto the end-of-spread questions if time allows.
Products from biomass Pupils research which plant biomasssubstances are used to make useful products.
What fuel? Pupils calculate the energy content of various foods tosee which would be suitable to use as a fuel.
Interactive animation in which pupils fit glucose molecules into thecorrect positions to build up sucrose, cellulose and starch.
Approx.timing
20 min
30 min
20 min
10 min
Target group
C H E S
R/G G R S
✔ ✔
✔
✔ ✔
Suggested alternative plenary activities (5–10 minutes)
Review learning
Play ‘What happens next?’starting fromphotosynthesis happeningin a tree.
Sharing responses
Share findings from Activity C4a to produce atable on the board of allthe group’s results.
Group feedback
In groups, pupils collateresults and conclusions fromActivity C4b.
Word game
Pupils write a spiderdiagram to show howphotosynthesis relates tothe production of biomass.
Looking ahead
Give pupils the list ofanswers. Ask them to workin pairs to devise questionsfor each of these answers.
Learning outcomes
Most pupils will ...
• identify photosynthesis as the source of biomass in plantsand describe ways in which humans use plant biomass
• explain that glucose made in photosynthesis is used forrespiration
• select, compare and synthesise information from differentwebsites to describe some ways in which humans use plantbiomass.
Some pupils, making less progress will ...
• identify some ways in which humansuse plant biomass
• explain that glucose made inphotosynthesis is used for energy, andcan be stored.
Some pupils, making more progress will ...
• find out about the molecular structuresof glucose and starch, appreciating therelationship between them.
Learning objectivesi Photosynthesis removes carbon dioxide from the air and produces oxygen.ii Distinguish between photosynthesis and respiration.iii Compare the word equations for photosynthesis and respiration.iv Deforestation can have a range of local and global effects on ecosystems.
Scientific enquiryv Relate respiration and photosynthesis to wider environmental issues and effects of scientific and technological developments.
(Framework YTO Sc1 9a)vi Consider issues of environmental protection from several perspectives.
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Play ‘What am I?’ focusingon products of plantbiomass.
Share learning objectives
• Describe how photosynthesisand respiration affectoxygen and carbon dioxidelevels in the air.
• Explain how cutting downforests can affect climateand living things.
• Recognise problems ofenvironmental protectionfrom different perspectives. (Sc1)
Problem solving
Use flashcards to rearrangethe reactants and productsof photosynthesis to remindpupils of the word equation.
Word game
In groups, pupils fill in thespeech bubbles for theconcept cartoon in responseto the problem ‘Ifphotosynthesis uses upcarbon dioxide, why doesthe total amount of carbondioxide in the atmospherealways stay the same?’
Capture interest
Play hangman to coverspelling of photosynthesis,respiration, chlorophyll, anddeforestation.
Suggested alternative main activitiesActivity
Textbook C5
Activity C5a ICT
Activity C5bICT
Learningobjectivessee above
i, ii, iii andiv
iv, v and vi
i, ii and iii
Description
Teacher-led explanation and questioning OR Pupils work individually,in pairs or in small groups through the in-text questions and thenonto the end-of-spread questions if time allows.
Dangers of deforestation Pupils produce a leaflet about the effectsof deforestation.
Maintaining the balance Pupils monitor oxygen and carbon dioxidelevels in a plant over 24 hours using ICT.
Approx.timing
20 min
35 min
20 min
Target group
C H E S
R/G G R S
✔
✔
Suggested alternative plenary activities (5–10 minutes)
Review learning
Pupils reorganisestatements aboutphotosynthesis into thecorrect order.
Complete a mind map,showing howphotosynthesis andrespiration are related.
Looking back
Pupils revise andconsolidate knowledge fromthe unit.
Learning outcomes
Most pupils will ...
• explain how photosynthesis and respiration can helpmaintain the balance of gases in the air
• describe how carbon dioxide and oxygenconcentrations in the air have varied over time
• identify the advantages and disadvantages of forestconservation for a range of people and living things.
Some pupils, making less progress will ...
• explain that animals use oxygen releasedfrom photosynthesis
• be aware of some of the advantages anddisadvantages of forest conservation for arange of living things.
Some pupils, making more progress will ...
• investigate the social and environmentalissues relating to forest conservation for a range of people and living things, inparticular considering the consequences of logging.
Key wordsNone
Out-of-lesson learningHomework C5Textbook C5 end-of-spread questionsRead about forest clearance and the consequent loss of biodiversity
Introduce the unit� Either draw the outline of the unit map on the board
then ask pupils to give you words to add, saying where toadd them. Suggest some words yourself when necessaryto keep pupils on the right track.
� Or give out the unit map and ask pupils to work ingroups deciding how to add the listed words to thediagram. Then go through it on the board as each groupgives suggestions.
Share learning objectives� Ask pupils to write a list of FAQs they would put on a
website telling people about plants and photosynthesis.Collect suggestions as a whole-class activity, steeringpupils towards those related to the objectives. Concludeby highlighting the questions you want them to be ableto answer at the end of the lesson.
Word game� Give out the true/false quiz sheets for pupils to complete
quickly, revealing aspects of their prior knowledge.
Brainstorming (1)� Show pupils a plant in a pot, and ask ‘Where does a plant
get its food?’.
� In groups, ask pupils to list as many ideas as they can.
Brainstorming (2)� Show pupils a plant that has been growing on a
windowsill, and one that has been growing in themiddle of the room (away from any windows).
� As a class, discuss what the differences are. If thereis time, ask them to explain the differences.
Equipmentpot plant growing on a windowsill for atleast a week; pot plant growing in alocation with light all around
AnswersPupils should notice that the plant on thewindowsill has bent over towards thelight. They may also notice that it becametaller more quickly than the other one.
Suggested alternative starter activities (5–10 minutes)
Introduce the unit
Unit map for Plantsand photosynthesis
Share learning objectives
• Describe what photosynthesis is.• Identify and control for relevant
variables in an investigation. (Sc1)• Explain how ideas about plant
growth have changed. (Sc1)
Word game
Pupils do true/false quizto reveal prior knowledgeabout photosynthesis.
Brainstorming (1)
Pupils suggest where aplant gets its food.
Brainstorming (2)
Pupils identify differencesbetween a plant on awindowsill and a plantgrowing normally in themiddle of the room.
Recap last lesson� Ask pupils to list the products and reactants of
photosynthesis.
Share learning objectives� Ask pupils to write a list of FAQs they would put on a
website telling people about leaves and photosynthesis.Collect suggestions as a whole-class activity, steeringpupils towards those related to the objectives. Concludeby highlighting the questions you want them to be ableto answer at the end of the lesson.
Word game� Ask pupils to play Snap! in pairs, using the cards on the
pupil sheet to match cell type with its adaptations.
Brainstorming (1)� In groups, pupils draw a plant cell and label as many
features as they can remember.
� Pupils should swap their drawings with other groups,and then write down what is missing and correct whatis wrong.
Brainstorming (2)� Show pupils a photograph of a solar panel, discuss its
purpose and how a solar panel is well suited to it.
➔ Pupil sheet
➔ Catalyst Interactive Presentations 3
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Pupils list the products andreactants of photosynthesis.
Share learningobjectives
• Describe why plants needchlorophyll and light tophotosynthesise.
• Explain why leaves aregood at photosynthesis.
• Identify patterns in thedata, and drawconclusions. (Sc1)
Word game
Pupils play Snap! with cardsshowing different cell typesand cards with theirspecialisations, to remindthem of how cells arespecialised to theirfunction.
Brainstorming (1)
In groups, pupils draw aplant cell and label as manyfeatures as they canremember.
Brainstorming (2)
Show pupils a photographof a solar panel, discuss itspurpose and how a solarpanel is well suited to it.Catalyst InteractivePresentations 3
Recap last lesson� Pupils list five features of a leaf that make it good at
photosynthesis.
� Ask individuals to suggest one feature and write it on theboard until there is a full list as a summary for all to writedown.
Share learning objectives� Ask pupils to write a list of FAQs they would put on a
website telling people about water and plants. Collectsuggestions as a whole-class activity, steering pupilstowards those related to the objectives. Conclude byhighlighting the questions you want them to be able toanswer at the end of the lesson.
Word game� Make a set of cards (true, false, unsure) for each pupil
from the teacher sheet (you could use a different colourcard for each word).
� Read out the statements on the teacher sheet. Pupils holdup the card for their answer simultaneously.
� If many pupils get an answer wrong, it may be becausethey won’t have met the ideas yet, and will need to waituntil the end of the lesson before they can get all theanswers right.
Problem solving� Show pupils a daffodil that has been standing in blue ink
for 24 hours.
� In pairs, ask pupils to discuss and suggest one idea forwhy the petals have turned blue.
� Join pairs into fours, and collate their answers to be fedback to a class discussion.
Capture interest� Show pupils photographs of a plant that has been
under-watered and a plant that has been over-watered.
� Ask pupils to describe the effect of lack of water onplants.
➔ Teacher sheet
Equipmentdaffodil left in blue ink for 24 hours
➔ Catalyst Interactive Presentations 3
Suggested alternative starter activities (5–10 minutes)
Recap last lesson
Pupils list five features of aleaf that make it good atphotosynthesis.
Share learningobjectives
• Describe how roots take inwater and nutrients fromthe soil.
• Describe how plants usewater for various reasons.
• Draw biological specimensusing a microscope. (Sc1)
Word game
Pupils play true/false quizby showing cards.
Problem solving
Show pupils a daffodil thathas been standing in blueink for 24 hours. In pairs,ask pupils to discuss andsuggest one idea for whythe petals have turned blue.
Capture interest
Show pupils photographs ofa plant that has beenunder-watered and a plantthat has been over-watered.Catalyst InteractivePresentations 3
Recap last lesson� Ask ‘What am I?’ focusing on products of plant biomass.
Remind pupils they can only ask closed questions,which can be answered yes or no. They have todetermine the answer with as few questions as possible.
Share learning objectives� Write the learning objectives on the board and show
why it is important that we know about these ideas.
� Tell pupils that photosynthesis and respiration controlthe amount of carbon dioxide in the air.
� Tell pupils that if this get unbalanced, the world’sclimate can be affected by the greenhouse effect.
� Tell pupils that cutting down rainforests could cause animbalance between oxygen and carbon dioxide.
Problem solving� Use flashcards to rearrange the reactants and products
of photosynthesis to remind pupils of the wordequation.
Word game� In groups, pupils fill in the speech bubbles for the
concept cartoon displayed as an OHT.
� Discuss as a class how carbon dioxide is released fromplants again by burning, respiration in animals and bymicrobe respiration of rotting plant material.
Capture interest� Play a game of hangman with the whole class to
reinforce vocabulary and spelling of the followingkey words.
Use flashcards to rearrangethe reactants and productsof photosynthesis to remindpupils of the word equation.
Word game
In groups, pupils fill in thespeech bubbles for theconcept cartoon in responseto the problem ‘Ifphotosynthesis uses upcarbon dioxide, why doesthe total amount of carbondioxide in the atmospherealways stay the same?’
Capture interest
Play hangman to coverspelling of photosynthesis,respiration, chlorophyll, anddeforestation.
If photosynthesis uses up carbon dioxide, why does thetotal amount of carbon dioxide in the atmosphereremain the same?
C-Starters.qxd 07-Jun-04 12:04 PM Page 12
C1aTeacher
activity notesWhat do plants need forphotosynthesis?
Running the activityNB: Plants must first be left in the dark for 24 hours to destarch them. After the destarched plants havebeen set up as shown, they must be left in a light place for a further 24 hours before the experiment.
Pupils work in small groups, or the activity could be carried out as a teacher demonstration. The pupilsthen test the leaves for starch, which should take about 30 minutes. Pupils test three leaves at the sametime, cutting a shape in the side of each to identify which are leaves 1, 2 and 3. Alternatively, pupils testone leaf at a time to ensure that they don’t get them mixed up. A preheated water bath will be needed forheating the ethanol (see Safety notes below). The leaves must be completely decolourised in ethanol forpupils to see the colour change with iodine.
Core: The method is given for the activity, and pupils come up with their own format for recording results.Questions ask them to draw conclusions about what the plant needs for photosynthesis.
Help: This sheet provides a table for pupils to record their results, and more structured questions lead themto their conclusions. Instructions for the experiment are not given on this sheet, so pupils will need helpwith the activity (pupils can be given access to the core sheet for more information), or the sheet could beused to accompany a teacher demonstration.
Expected outcomesIodine will change from orange to black when starch is present in the leaf. The presence of starchindicates that the plant has been photosynthesising. Areas of leaves covered with black tape will not turniodine black, indicating that the leaf needs light for photosynthesis. Leaves kept in the presence ofsodium hydroxide will not turn iodine black, indicating that carbon dioxide is needed for photosynthesis.Leaves that have been kept in the light with carbon dioxide will turn iodine black, indicating that starchhas been produced by photosynthesis.
PitfallsThe plants must be thoroughly destarched before use, otherwise false results will be obtained. Old leavesshould be avoided. Put soda lime in the conical flasks before the start of this activity.
Safety notesEye protection required. Warn pupils that soda lime is corrosive and that iodine is harmful as well asproducing stains on skin and clothing.
Ethanol is flammable. Use a hotplate for the water bath to heat the ethanol. Do not use a naked flame toheat it. Warn pupils to take care with boiling water. If they scald themselves, cool the skin with plenty ofcold running water.
AnswersCore:
1 To test whether light is needed for photosynthesis. 2 To test whether carbon dioxide is needed forphotosynthesis. 3 A control. 4 Light is needed for photosynthesis because starch only formed in theparts of the leaf that had access to light. 5 Carbon dioxide is needed for photosynthesis because the leafwithout carbon dioxide did not make starch. 6 To destarch the leaves (so that the plant uses up any starchalready produced in the leaves).
Help:
1 Orange, blue/black, photosynthesis. 2 It turned blue/black in those areas with light, and stayed orangein the area under the tape without light. 3 Light is needed for photosynthesis. 4 No colour change.5 Carbon dioxide is needed for photosynthesis. 6 Colour changed to blue/black. 7 Starch is present, sothe leaf has been photosynthesising. 8 As a control, against which to compare leaf 1 and leaf 2, to see theeffect of removing light and carbon dioxide.
Type Purpose DifferentiationPractical Pupils test leaves for starch in order to find out whether a plant needs light and carbon
dioxide for photosynthesis.Core, Help
C-Teachers.qxd 17-Jun-04 8:33 PM Page 1
C1aTechnician
activity notesWhat do plants need forphotosynthesis?
Equipment
For your informationRunning the activityNB: Plants must first be left in thedark for 24 hours to destarch them.After the destarched plants have beenset up as shown, they must be left ina light place for a further 24 hoursbefore the experiment.
Pupils work in small groups, or the activity could be carried out as a teacher demonstration. The pupils testthe leaves for starch, which should take about 30 minutes. Pupils test three leaves at the same time, cuttinga shape in the side of each to identify which are leaves 1, 2 and 3. Alternatively, pupils should test one leafat a time to ensure that they don’t get them mixed up. A preheated water bath will be needed for heatingthe ethanol (see Safety notes below). The leaves must be completely decolourised in ethanol for pupils tosee the colour change with iodine.
Core: The method is given for the activity, and pupils come up with their own format for recording results.Questions ask them to draw conclusions about what the plant needs for photosynthesis. Question 4 couldbe used as an extension question.
Help: This sheet provides a table for pupils to record their results, and more structured questions lead themto their conclusions. Instructions for the experiment are not given on this sheet, so pupils will need helpwith the activity (pupils can be given access to the core sheet for more information), or the sheet could beused to accompany a teacher demonstration.
Expected outcomesIodine will change from orange to black when starch is present in the leaf. The presence of starch indicatesthat the plant has been photosynthesising. Areas of leaves covered with black tape will not turn iodineblack, indicating that the leaf needs light for photosynthesis. Leaves kept in the presence of sodiumhydroxide will not turn iodine black, indicating that carbon dioxide is needed for photosynthesis. Leavesthat have been kept in the light with carbon dioxide will turn iodine black, indicating that starch has beenproduced by photosynthesis.
PitfallsThe plants must be thoroughly destarched before use, otherwise false results will be obtained. Old leavesshould be avoided. Put soda lime in the conical flasks before the start of this activity.
Safety notesEye protection required. Warn pupils that soda lime is corrosive and that iodine is harmful as well asproducing stains on skin and clothing.
Ethanol is flammable. Use a hotplate for the water bath to heat the ethanol. Do not use a naked flame toheat it. Warn pupils to take care with boiling water. If they scald themselves, cool the skin with plenty ofcold running water.
Type Purpose DifferentiationPractical Pupils test leaves for starch in order to find out whether a plant needs light and carbon
dioxide for photosynthesis.Core, Help
leaf 1black tape (thisstops the light)
leaf 2soda lime (thisremoves all thecarbon dioxide)
plant has been left indarkness for 24 hours
For the class:
� hotplates for heating water baths
For each group:
� destarched plant, e.g. geranium� black tape
� conical flask containing soda lime� split bung to fit around leaf stalk� clamp stand and clamp� forceps� scalpel and cutting tile (optional)� Bunsen burner� heatproof mat� tripod and gauze
� beaker (250 cm3)� boiling tube� tube holder� ethanol� white tile� iodine dropper bottle� paper towel
C-Technician.qxd 18-Jun-04 11:51 AM Page 1
C1aActivity
CoreWhat do plants need forphotosynthesis?
In photosynthesis, plants make sugars which they store as asubstance called starch. If you find starch in a plant’s leaves, youknow it has been carrying out photosynthesis. You are going totest whether leaves can carry out photosynthesis without sunlight,and without carbon dioxide.
Obtaining evidence1 Set up the plant as shown in the diagram.
1 What is leaf 1 testing for?2 What is leaf 2 testing for?3 You are going to take a third, untreated leaf (leaf 3), from the
plant. What is the purpose of this leaf?
2 Take leaves 1 and 2 off the plant. Also take one more leaf(leaf 3), which is untreated. Make sure you remember whichleaf is which! You can do this by cutting a different shape outof the side of each leaf and noting which leaf has which shape.
3 Using forceps, place the leaves in 50 cm3 of boiling water ina beaker. After 2 minutes, turn off the Bunsen burner.
4 Take the leaves out of the water and soak them in a boilingtube of warm ethanol in a water bath until they gocolourless, as shown.
5 Dip the leaves in cool water, spread them out on a white tileand test them with a few drops of iodine. This turns fromorange to black if there is starch present.
Presenting the results6 Record the results of the starch test for each leaf.
Considering the evidence4 What do the results for leaf 1 tell you about photosynthesis?5 What do the results for leaf 2 tell you about photosynthesis?6 Why do you think the leaves were kept in the dark for 24 hours
Leaf 2 (sodium hydroxide solution – no carbon dioxide)
Leaf 3
Wear eyeprotection.
Ethanol isflammable.Do not use a
Bunsen burner near it.
Soda lime is corrosive;avoid all contact.
Take care with boilingwater.
Iodine solution isharmful. It can stain yourskin and your clothes.
C-Activities.qxd 18-Jun-04 9:39 AM Page 2
C1bTeacher
activity notesWhat gas is produced byphotosynthesis?
Running the activityNB: This activity needs to be run over two lessons.
The pupils work in groups, or the activity can be run as a teacher demonstrationto save time. Pupils are instructed to set up the experiment and leave it until thenext lesson on a windowsill. The gas that has collected the next day is tested with a glowing splint, or the gas can be produced more quickly by shining a lamp on the plant. Questions lead pupils to draw conclusions and analyse theexperiment.
Expected outcomesThe glowing splint will be relit, showing that the gas that is produced by thephotosynthesising plant is oxygen.
Safety notesPupils should take care with the Bunsen burners.
PitfallsIt is often difficult to collect a substantial enough amount of oxygen for theglowing splint test. Be prepared to use an oxygen cylinder to prepare a tube ofoxygen to put over the pond weed before students arrive.
ICT opportunitiesIt should be possible to set up a datalogging experiment to observe fluctuationsin the rate of photosynthesis by measuring the concentration of oxygen inwater surrounding pond weed over 24 hours.
Answers1 oxygen
2 e.g. shine a bright light on the plant throughout the 24-hour period; growthe plant in an enriched atmosphere of carbon dioxide.
Type Purpose DifferentiationPractical Pupils observe that plants make a gas during photosynthesis and test the gas to find
out whether it is oxygen.Core
C-Teachers.qxd 17-Jun-04 8:33 PM Page 2
C1bTechnician
activity notesWhat gas is produced byphotosynthesis?
EquipmentFor each group (or teacher demonstration):
� water plant, e.g. pond weed� glass funnel� Plasticine to support funnel in beaker� beaker (250 cm3)� test tube� splint� Bunsen burner� heatproof mat� lamp (optional)
For your informationRunning the activity
NB: This activity needs to be run over two lessons.
The pupils work in groups, or the activity can be run as a teacher demonstrationto save time. Pupils are instructed to set up the experiment and leave it until thenext lesson on a windowsill. The gas that has collected is tested with a glowingsplint, or the gas can be produced more quickly by shining a lamp on the plant.Questions lead pupils to draw conclusions and analyse the experiment.
Expected outcomesThe glowing splint will be relit, showing that the gas that is produced by thephotosynthesising plant is oxygen.
Safety notesPupils should take care with the Bunsen burners.
PitfallsIt is often difficult to collect a substantial enough amount of oxygen for theglowing splint test. Be prepared to use an oxygen cylinder to prepare a tube ofoxygen to put over the pond weed before students arrive.
Type Purpose DifferentiationPractical Pupils observe that plants make a gas during photosynthesis and test the gas to find
out whether it is oxygen.Core
1
waterfunnelpond weed
plasticine support
C-Technician.qxd 18-Jun-04 11:51 AM Page 2
C1bActivity
CoreWhat gas is made inphotosynthesis?
A plant uses carbon dioxide and water to make food byphotosynthesis. You are going to find out what else is madeduring photosynthesis. You are going to collect a gas from aplant and test it with a glowing splint. If the splint relights,the gas is oxygen.
Obtaining evidence
1 Set up the beaker as shown in the diagram.2 Fill the test tube with water. Put your thumb over the
end then turn the test tube upside down. Take carethat no air gets in the test tube.
3 Carefully lower the test tube into the beaker so the endyou are holding is under the water above the funnel.
4 Remove your thumb and lower the test tube over the end of the funnel.
5 Leave the beaker on a windowsill until the next lesson.6 Next lesson, take a splint and blow it out so that it is
glowing.7 Slide your thumb over the end of the test tube under
the water, then remove the test tube carefully. Turn theright way up.
8 Taking care not to let all the collected gas escape,quickly remove your thumb and place the glowingsplint inside the test tube.
9 Record what happens to the splint.
Considering the evidence
1 What gas was produced during this experiment?2 Think about how you might be able to make the plant
produce the gas faster. Suggest ways you might try.3 What else is produced by photosynthesis?
Running the activityThis activity involves pupils analysing graphs to make conclusions aboutphotosynthesis. It asks pupils to think about the effects of changing gas levelson plants in a greenhouse, and leads them into thinking about limiting factors.
Answers1 yes
2 Because carbon dioxide is a reactant of photosynthesis, giving a plant morecarbon dioxide will make it photosynthesise more.
3 no
4 Oxygen is not a reactant in photosynthesis.
5 Light, water.
6 If you increased the amount of water and light as well, the speed ofphotosynthesis would increase, showing that these factors were previouslyin short supply.
Type Purpose DifferentiationPaper Pupils analyse data about gas levels in a greenhouse, applying their knowledge about
photosynthesis.Extension
C-Teachers.qxd 17-Jun-04 8:33 PM Page 3
C1cActivity
ExtensionGases in the greenhouse
Jack knows that plants need carbon dioxide and oxygen tosurvive. He wondered if he could increase the speed ofphotosynthesis by increasing the amount of carbon dioxideand oxygen available to the plants in his aquarium. Hemeasured the speed of photosynthesis by counting thebubbles coming off his plants.
1 Was the increase in speed ofphotosynthesis affected by anincrease in the amount ofcarbon dioxide available?
2 Explain your answer to question 1.3 Was the increase in speed of
photosynthesis affected by anincrease in the level of oxygenavailable?
4 Explain your answer to question 3.
Look again at the graph of carbondioxide levels. When plants aresupplied with more and more carbondioxide, the increase in the speed ofphotosynthesis eventually stops.
5 Even if plants are supplied with a lot of carbon dioxide, they may beshort of other factors required forphotosynthesis. What are thesefactors?
6 Explain how you could test whichof the factors in your answer toquestion 5 really is in short supply.
Graph of speed of photosynthesis against CO2 levels
Increase inspeed ofphotosynthesis
Level of oxygen
Graph of speed of photosynthesis against O2 levels
C-Activities.qxd 18-Jun-04 9:40 AM Page 4
C2aTeacher
activity notesWhen do plants grow fastest?
Running the activityNB: This activity needs to be run over two lessons.
This activity will probably be run as a teacher demonstration unless there areenough position sensors available for each group of pupils. The growingseedlings are set up and left by a window for three days. The results are moreconvincing if the experiment can be left longer. Pupils are asked questions,leading them to a conclusion, and also to evaluate the experiment.
Other relevant materialSkill sheet 6: Interpreting graphsSkill sheet 26: Designing a spreadsheetSkill sheet 28: Calculations with a spreadsheet
Expected outcomesThe position sensor will indicate a general increase in size. There will be amarked increase in the growth of plants during the day that may be lessobvious with younger plants.
PitfallsDo not forget to water the seedlings. The position sensor connections are oftenvery delicate and easily disturbed by pupils, perhaps from other classes.
Safety notesBe aware that some seeds may be treated with fungicides and pesticides. Pupilsshould wash their hands after handling seeds or plants.
ICT opportunitiesIt would be possible to set up a spreadsheet for the results and subsequentcalculations.
Answers1 During the day, as there is more photosynthesis then.
2 During the night, as there is no photosynthesis then.
3 Doing the experiment a few times would make the results more reliable, incase a mistake was made. Using more plants would make the results morereliable, in case there was something wrong with the plants. Carrying outthe experiment for a shorter period of time would not improve theexperiment. Carrying out the experiment for a longer period of time wouldmake the results more obvious to see.
Type Purpose DifferentiationICT Demonstration using datalogging to compare the growth of seedlings during daylight
and at night. A position sensor is used to monitor the growth.Core
C-Teachers.qxd 17-Jun-04 8:33 PM Page 4
C2aTechnician
activity notesWhen do plants grow fastest?
Other relevant materialSkill sheet 6: Interpreting graphsSkill sheet 26: Designing a spreadsheetSkill sheet 28: Calculations with a spreadsheet
EquipmentFor the class:� computer� interface� position sensor� seedlings, e.g. of wheat growing on growth medium,
e.g. cotton wool (see tips below)� wire or arm with counterweight� cotton thread� clamp stand� printer (optional)
For your informationRunning the activityNB: This activity needs to be run over two lessons.
This activity will probably be run as a teacher demonstration unless there are enough position sensorsavailable for each group of pupils. The growing seedlings are set up and left by a window for three days.The results are more convincing if the experiment can be left longer. Pupils are asked questions, leadingthem to a conclusion, and also to evaluate the experiment.
Expected outcomesThe position sensor will indicate a general increase in size. There will be a marked increase in the growth ofplants during the day that may be less obvious with younger plants.
PitfallsDo not forget to water the seedlings. The position sensor connections are often very delicate and easilydisturbed by pupils, perhaps from other classes.
Safety notesBe aware that some seeds may be treated with fungicides and pesticides. Pupils should wash their handsafter handling seeds or plants.
Type Purpose DifferentiationICT Demonstration using datalogging to compare the growth of seedlings during daylight
and at night. A position sensor is used to monitor the growth.Core
wire or armwith small
counterweightto keep
cotton taut
position sensor
cotton
seedling
interface computer
C-Technician.qxd 18-Jun-04 11:51 AM Page 3
C2aActivity
CoreWhen do plants grow fastest?
You are going to follow the growth of a plant over three daysusing datalogging equipment. You are going to use a positionsensor to find out when a plant grows the fastest.
Obtaining evidence
1 Your teacher will set up the apparatus as shown. The cotton mustbe tight.
2 The computer will record the growth. Note down the time that it started.3 Leave the plant by a window for three days. Make sure the plant has
enough water.4 The computer will show a graph of the growth of the seedling against
the time taken to grow.
Presenting the results
5 Draw a sketch of the graph shown on the computer (or your teachermay give you a printout).
6 Label your graph with the time when you started the experiment.
Considering the evidence
1 When did the plant grow the quickest? Why do you think this is?2 When did the plant grow the slowest? Why do you think this is?
Evaluating
3 Think about how this experiment could be made better. Would each of thefollowing suggestions improve the experiment or not? Explain your answers.
� doing the experiment a few times� using more plants� carrying out the experiment for a shorter period of time� carrying out the experiment for a longer period of time
Do not eatthe seeds orplants.
Wash your handsafterwards.
C-Activities.qxd 18-Jun-04 9:40 AM Page 5
C2bTeacher
activity notesLooking at leaves
Running the activityPupils work in pairs. The activity sheet gives a method for carrying out thepractical, and directs pupils to record a labelled diagram of the slide. Amicroscope could be linked to a video camera (e.g. Flexicam) to display slides tothe whole class.
Other relevant materialSkill sheet 1: Using a microscope
Expected outcomesPupils produce a labelled drawing of a section through the leaf as seen underthe microscope.
Safety notesPupils should take care with microscopes and slides. Microscopes using daylightillumination must never be used where direct sunlight may strike the mirror.Permanent damage to the retina may be caused by direct sunlight passingthrough the microscope into the eye.
ICT opportunitiesUse a Flexcam or QX3 digital microscope and projector to enlarge themicroscope image for discussion as a class.
Answers1 Palisade cells: contain the chloroplasts.
Chloroplasts: contain chlorophyll to trap light energy.
Air spaces: let gases go to and from stomata and spongy/palisade cells.
Stomata: let gases in and out of the leaf.
Waxy cuticle: prevents water being lost from the top surface of the leaf.
Vein: brings water from the roots, and takes glucose away to the rest ofthe plant.
Type Purpose DifferentiationPractical Pupils practise using a microscope and reinforce knowledge of the structure and
function of the leaf. Pupils look at pre-prepared leaf slides.Core
C-Teachers.qxd 17-Jun-04 8:33 PM Page 5
C2bTechnician
activity notesLooking at leaves
Other relevant materialSkill sheet 1: Using a microscope
EquipmentFor the class:
� video camera, e.g. Flexicam (optional)� microscope
For each pair:
� pre-prepared (bought) slide of TS of a leaf, stained� microscope
For your informationRunning the activityPupils work in pairs. The activity sheet gives a method for carrying out thepractical, and directs pupils to record a labelled diagram of the slide. A microscopecould be linked to a video camera (e.g. Flexicam) to display slides to the whole class.
Expected outcomesPupils produce a labelled drawing of a section through the leaf as seen underthe microscope.
Safety notesPupils should take care with microscopes and slides. Microscopes using daylightillumination must never be used where direct sunlight may strike the mirror.Permanent damage to the retina may be caused by direct sunlight passing throughthe microscope into the eye.
The leaf of a plant carries out photosynthesis. Each part of theleaf has a special function to help it carry out photosynthesis.You are going to look at a leaf under a microscope.
Obtaining evidence1 Put the slide on the microscope stage.2 Focus on your slide using the low power lens.3 Now look at the leaf using the high power lens.
Presenting the results4 Make a careful drawing in pencil to show what the
leaf looks like under the microscope.5 Label the parts of the leaf you can see.
Considering the evidence1 How does the structure of each part of the leaf help
the leaf to carry out photosynthesis?
The leaf of a plant carries out photosynthesis. Each part of theleaf has a special function to help it carry out photosynthesis.You are going to look at a leaf under a microscope.
Obtaining evidence1 Put the slide on the microscope stage.2 Focus on your slide using the low power lens.3 Now look at the leaf using the high power lens.
Presenting the results4 Make a careful drawing in pencil to show what the
leaf looks like under the microscope.5 Label the parts of the leaf you can see.
Considering the evidence1 How does the structure of each part of the leaf help
the leaf to carry out photosynthesis?
Take care withmicroscopesand slides.
Never use a microscopewhere direct sunlightmight get into it.
Take care withmicroscopesand slides.
Never use a microscopewhere direct sunlightmight get into it.
C-Activities.qxd 18-Jun-04 9:40 AM Page 6
C3aTeacher
activity notesLooking at root hairs
Running the activityPupils work in pairs. The activity sheet gives a method for carrying out thepractical, and directs pupils to record a labelled diagram of the slide. Amicroscope could be linked to a video camera (e.g. Flexicam) to display slides tothe whole class.
Other relevant materialSkill sheet 1: Using a microscope
Expected outcomesPupils produce a labelled drawing of a root as seen under the microscope.
Safety notesPupils should take care with microscopes and slides. Microscopes using daylightillumination must never be used where direct sunlight may strike the mirror.Permanent damage to the retina may be caused by direct sunlight passingthrough the microscope into the eye.
ICT opportunitiesUse a Flexicam or QX3 digital microscope and projector to enlarge themicroscope image for discussion as a class.
Answers1 Roots are branched and have root hairs to make sure they can absorb as
Type Purpose DifferentiationPractical Pupils practise using a microscope and reinforce knowledge of the structure and
function of the root. Pupils look at pre-prepared slides of roots showing root hairs.Core
C-Teachers.qxd 17-Jun-04 8:33 PM Page 6
C3aTechnician
activity notesLooking at root hairs
Other relevant materialSkill sheet 1: Using a microscope
EquipmentFor the class:
� video camera, e.g. Flexicam (optional)� microscope
For each pair:
� pre-prepared (bought) slide of TS or LS of a root, stained to show root hairs� microscope
For your informationRunning the activityPupils work in pairs. The activity sheet gives a method for carrying out thepractical, and directs pupils to record a labelled diagram of the slide. A microscopecould be linked to a video camera (e.g. Flexicam) to display slides to the whole class.
Expected outcomesPupils produce a labelled drawing of a root as seen under the microscope.
Safety notesPupils should take care with microscopes and slides. Microscopes using daylightillumination must never be used where direct sunlight may strike the mirror.Permanent damage to the retina may be caused by direct sunlight passing throughthe microscope into the eye.
Never use a microscopewhere direct sunlightmight get into it.
C-Activities.qxd 18-Jun-04 9:40 AM Page 7
C3bTeacher
activity notesWater transport in celery
Running the activityNB: This activity needs to be run over two lessons.
Pupils work in groups. They are instructed to leave celery stalks in dyed waterovernight and observe them the next day. To carry out the activity in the sameday, the celery stalks need to be left for at least a few hours before they are used.Alternatively, a cool hair dryer blowing over the leaves will speed up themovement of dye up the stalk.
The next day, pupils make a slide of a thin cross-section and observe it under amicroscope. Structured questions lead them to analyse the structure andfunction of the veins.
As a demonstration in parallel with this activity, a white carnation can be leftin dyed water overnight to show pupils that the dye travels up the veins andcolours the flower.
Other relevant materialSkill sheet 1: Using a microscope
Expected outcomesThe celery stalk will become stained in the parts of the veins that carry water(xylem). With a very thin cross-section of the stalk, the structure of the stainedveins should become clearly visible under a light microscope.
PitfallsMake sure pupils cut very thin cross-sections. Some pupils may need helpwith this.
Safety notesPupils must use knives carefully. Take care with microscopes and slides.Microscopes using daylight illumination must never be used where directsunlight may strike the mirror. Permanent damage to the retina may be causedby direct sunlight passing through the microscope into the eye. Remind pupilsnot to eat the celery.
Type Purpose DifferentiationPractical Pupils observe coloured water travelling up the veins in a plant to reinforce knowledge
of the structure and function of veins in plants.Core
C-Teachers.qxd 17-Jun-04 8:33 PM Page 7
C3bTechnician
activity notesWater transport in celery
Other relevant materialSkill sheet 1: Using a microscope
Equipment
For your informationRunning the activityNB: This activity needs to be run over two lessons.
Pupils work in groups. They are instructed to leave celery stalks in dyed water overnight andobserve them the next day. To carry out the activity in the same day, the celery stalks needto be left for at least a few hours before they are used. Alternatively, a cool hair dryerblowing over the leaves will speed up the movement of dye up the stalk.
The next day, pupils make a slide of a thin cross-section and observe it under a microscope.Structured questions lead them to analyse the structure and function of the veins.
As a demonstration in parallel with this activity, a white carnation can be left in dyed waterovernight to show pupils that the dye travels up the veins and colours the flower.
Expected outcomesThe celery stalk will become stained in the parts of the veins that carry water (xylem). Witha very thin cross-section of the stalk, the structure of the stained veins should becomeclearly visible under a light microscope.
PitfallsMake sure pupils cut very thin cross-sections. Some pupils may need help with this.
Safety notesPupils must use knives carefully. Take care with microscopes and slides. Microscopes usingdaylight illumination must never be used where direct sunlight may strike the mirror.Permanent damage to the retina may be caused by direct sunlight passing through themicroscope into the eye. Remind pupils not to eat the celery.
Water and minerals are taken up from the soil into the rootsof a plant. They are transported around the plant through theveins. You are going to look at these veins using a microscope.
1 Stand some celery stalks in red dye. Leave them overnight.2 The next day, look at how far the dye has moved up the stalk.
Record your observations.3 Use a knife to cut a thin cross-section of dyed celery stalk.4 Place the section onto the slide. Put a few drops of distilled
water on the section. Carefully lower a coverslip over the slideas shown.
Presenting the results
5 Draw a sketch of what you can see.
Considering the evidence
1 Look back at how far the dye moved up the stem. How far upthe plant do you think the veins go?
2 What is the function of the veins in the plant?3 Describe how the structure of the vein helps it to carry out its
function in the plant.
Take care withthe knife. It isvery sharp.
Take care withmicroscopes and slides.
Never use a microscopewhere direct sunlightmight get into it.
Do not eat the celery.
C-Activities.qxd 18-Jun-04 9:40 AM Page 8
C4aTeacher
activity notesProducts from biomass
Running the activityCore: Pupils should work independently. You could provide a range of referencesources for pupils in the classroom, or the research element may be carried out as ahomework activity.
Help: Pupils cut out and match statements and pictures from the activity sheet, tocomplete a description of how sugar cane is used in Brazil to produce fuel alcohol.
Other relevant materialSkill sheet 4: Web searches (for Extension)
Possible websites:
BeanfeastEuropaBio’s GM soya section
Golden syrupSilver Spoon website
Corn oil JD Hodges nutritional information
Vegetable protein Healthnotes foodnotes section
Cotton and paperConservation Online cellulose information
Paper and woodA brief history of paper making
Expected outcomesCore: Pupils make a table showing what they have found out about the differentproducts.
Help: Pupils make a poster or leaflet from their matched descriptions and pictures.
PitfallsEnsure pupils only use appropriate websites.
ICT opportunitiesExtension work could include searching the Internet for fuel alcohol productionfrom sugar cane. Pupils could try searching the key words biomass, fuel, sugarcane and Brazil. Pupils could produce a leaflet, poster or presentation of theirfindings.
Help: The correct order is: Brazil is trying to save money... The sugar cane ischopped... The sugar cane is mixed...The fermented liquid is... The alcohol is...
Type Purpose DifferentiationICT Core pupils research which plant biomass substances are used to make different products.
Help pupils find out how alcohol for use as fuel is produced from sugar cane in Brazil. Thiscould also form the basis of an Extension activity (no sheet).
Many products we buy are parts of plants or have been madefrom plants. They may be produced from the proteins,cellulose, starch, oils and sugars that form part of the plants’biomass. You are going to do some research into plantproducts.
1 Look at this range of products.
2 Use the Internet and other resources to find out which substancesfrom the plants’ biomass are contained in each of these products.
In some parts of the world biomass is used to produce energy. Inthis activity you are going to find out how sugar cane is used inBrazil to produce alcohol for use as car fuel.
1 Cut out the pictures and the descriptions in the boxes below.2 Arrange them in the correct order.3 Use them to make a poster or a leaflet about fuel from biomass.
The sugar is mixed with yeast andleft to ferment. The yeast feeds onthe sugar, changing it to alcohol.
The alcohol is mixed with petrol andused by cars and lorries.
The sugar cane is chopped up andcrushed to squeeze out the juice.The juice is heated. The waterevaporates leaving sugar crystals.
Brazil is trying to save money byreducing oil imports. Sugar canecontains sugars made byphotosynthesis. They are changedinto alcohol that will burn, releasingenergy from the biomass.
The fermented liquid is distilled byheating it to 70 ºC. The vapour thatcomes off is then cooled. Itcondenses to form alcohol.
C-Activities.qxd 18-Jun-04 9:40 AM Page 10
C4bTeacher
activity notesWhat fuel?
Running the activityPupils should work independently. You may have to work through an exampleon the board for pupils to understand the mathematics involved.
ICT opportunitiesIt would be possible to set up a spreadsheet for the results and subsequentcalculations.
Pupils could search the Internet for more information on how biomass is usedfor fuel.
Type Purpose DifferentiationPaper Pupils use information about the different nutrients in food to calculate the best food
to use as a fuel. The activity links the ideas of nutrients and biomass.Extension
C-Teachers.qxd 17-Jun-04 8:33 PM Page 9
C4bActivity
ExtensionWhat fuel?
We use petrol as a fuel for our cars. This is because petrol contains over 4500 kJ of energy in every 100 g! But what would happen if the petrol ran out, and we had to use plant biomass to make fuel? You are going to analyse different foods made from plants to see if any of them would provide as much energy per gram as petrol.
1 Look at the table.It tells you theenergy content ofthe main nutrientsin food.
2 Now look at the nutritional labels for honey, cooking oil, rice and couscous.They show you how many grams of each nutrient is in 100 g of food.
1 Calculate how much energy is provided by 100 g of each food.2 Do any of the foods provide more energy per 100 g than petrol?3 Which food would be the best replacement for petrol?
Running the activityPupils work in pairs to produce a campaign leaflet about deforestation. Theycould do this on paper or using desktop publishing software. Try to make themfocus on explaining the science as clearly as possible, on engaging the readerwith the issues, and on giving more than one person’s opinion on the issues.
Other relevant materialSkill sheet 4: Web searches
ICT opportunitiesPupils could search the Internet for more information about deforestationand the greenhouse effect. Useful websites could include Greenpeace andFriends of the Earth.
Pupils could produce their leaflets using desktop publishing software.
People are cutting down forests all over the world. Thisdeforestation could have a catastrophic effect on carbondioxide levels in the atmosphere. You are going to design aleaflet to explain the dangers of deforestation.
1 Read the magazine article below. Look at any otherinformation you have from other sources about the dangersof deforestation.
2 You should decide which pieces of information would grabpeople’s attention and make them take notice. Use thisinformation on the front cover.
3 Inside the leaflet, you need to use science to explain whydeforestation is a problem. You should also mention whylogging is carried out by subsistence farmers and bycommercial companies.
The world’s forests aredisappearing. Four fifths of
them have been cut downbecause of mining, agricultureand commercial logging. TheAmazon rainforest is the size ofWestern Europe – an area of370 million hectares. Over thepast 30 years 15% of theBrazilian part of the forest hasbeen completely destroyed.This is equivalent to the area ofFrance!
About 2% of logs are cutdown by subsistence farmers.They’ve been cutting trees inthe same ‘small-scale’ waywithout any ill effects on theforest for hundreds of years. Butabout 80% of logging in theAmazon is done illegally. Even
the majority of commerciallogging authorised by somegovernments is very destructiveand is processed in a verywasteful way. On average, onlyone third of wood cut down inthe forest actually ends up inthe final product.
To understand whydeforestation is a problem, you need to understand thegreenhouse effect. Carbondioxide and other ‘greenhousegases’ act a little like the glassof a greenhouse and stop heatescaping from the Earth. Ifthere weren’t any greenhousegases in the atmosphere, itwould be about –5 °C all overthe world, and everywherewould be covered with ice.
So, it is important tomaintain a balance ofgreenhouse gases. The largeforests meant that it waspossible to keep increases incarbon dioxide (mainly fromvolcanic activity) in checkbecause trees convert carbondioxide into glucose andcellulose and release oxygenthrough photosynthesis. Now,only about half the world’sforests that existed a thousandyears ago remain, and muchmore greenhouse gases than inthe past are spewed into theatmosphere by burning fossilfuels. This has thrown thesystem out of balance, and theatmosphere is warming up. Weneed to stop deforestation now!
What’s happening in the Amazon?
C-Activities.qxd 18-Jun-04 9:40 AM Page 12
C5bTeacher
activity notesMaintaining the balance
Running the activityPupils work in small groups to set up datalogging equipment over two lots of24 hours. It would be sensible to ask pupils to use the datalogging software toprepare and print the graphs immediately after finishing data collection.
Other relevant materialSkill sheet 27: Graphs with a spreadsheet
Expected outcomesPupils should produce graphs of carbon dioxide and oxygen levels over time,and they should answer the questions.
PitfallsThe pH and oxygen sensors can sometimes behave unpredictably. It isimportant to ensure they are calibrated in advance.
Be very gentle with both probes to avoid breaking them.
Safety notesWash your hands after handling the pond weed.
Answers1 carbon dioxide + water → glucose + oxygen (photosynthesis)
glucose + oxygen → carbon dioxide + water (respiration)
Type Purpose DifferentiationICT Pupils use datalogging equipment to look at the interrelationship between
photosynthesis and respiration.Core
C-Teachers.qxd 17-Jun-04 8:33 PM Page 11
C5bTechnician
activity notesMaintaining the balance
Other relevant materialSkill sheet 27: Graphs with a spreadsheet
EquipmentFor each group:
� oxygen sensor� pH sensor� datalogging control box� computer� conical flask� split rubber bung for conical flask� pond weed
For the class:
� sodium hydrogen carbonate� spatula
For your informationRunning the activityPupils work in small groups to set up datalogging equipment over two lots of24 hours. It would be sensible to ask pupils to use the datalogging software toprepare and print the graphs immediately after finishing data collection.
Expected outcomesPupils should produce graphs of carbon dioxide and oxygen levels over time,and they should answer the questions.
PitfallsThe pH and oxygen sensors can sometimes behave unpredictably. It isimportant to ensure they are calibrated in advance.
Be very gentle with both probes to avoid breaking them.
Safety notesWash your hands after handling the pond weed.
Type Purpose DifferentiationICT Pupils use datalogging equipment to look at the interrelationship between
photosynthesis and respiration.Core
C-Technician.qxd 18-Jun-04 11:52 AM Page 7
C5bActivity
CoreMaintaining the balance
To really see how respiration and photosynthesis fit together, you will study a plant over 24 hours and find out what gases it gives out. You will use a dataloggerbecause you can’t stay in school overnight. An oxygen probe will measure theamount of dissolved oxygen in the water. A pH probe will measure the pH of the water. The more carbon dioxide in the water, the more the pH goes down. This means we can use a pH probe to see how carbon dioxide levels change.
1 Set up the apparatus shown in the diagram.The way you do this will depend on yourdatalogging equipment.
2 Make sure the ends of the oxygen sensorand pH sensor are pushed between theleaves of the pond weed.
3 Allow the datalogger to run for 24 hours.4 Using your datalogging software, plot a
graph with time on the x-axis (going across) and oxygen on the y-axis (going up and down).
5 Repeat step 4, but for pH (carbon dioxide) instead of oxygen.
Considering the evidence
1 Write down the word equations for photosynthesis and respiration.
If photosynthesis and respiration happen at the same speed in the plant, then the levels of each gas in the water should stay constant.
2 When do plants respire?3 When do plants photosynthesise?4 At what time was the most carbon dioxide released into the water?5 At the same time, was photosynthesis happening more quickly than
respiration, or vice-versa?6 At what time was the most oxygen released into the water?7 At the same time, was respiration happening more quickly than
Review learning� Pupils fill in a template ‘cooking recipe’ for photosynthesis
on the pupil sheet.
� Choose pupils to read out their recipe to the class.
Sharing responses� Pupils collate results and conclusions from Activity C1a or
C1b about photosynthesis.
� Conclude feedback by writing a word equation as a class.
Group feedback� In small groups, pupils discuss their answers to Activity
C1c.
� They should discuss why it may be a good idea to moveplants out of hospital wards at night.
Word game� In small groups, pupils prepare four questions about the
lesson’s content, for which they know the answers.
� Groups should swap sets of questions and try to answerthem.
Looking back� Set the question for pairs to consider and suggest answers
to. Then ask them to share their responses with otherpupils. Make it clear they may not know the answer andthey need to suggest their ideas and predictions.
� Pupils can summarise the suggestions and record them intheir books, to reconsider after further lessons.
➔ Pupil sheet
QuestionHow do plants get the reactants forphotosynthesis into their leaves?
Suggested alternative plenary activities (5–10 minutes)
Review learning
Pupils fill in a template‘cooking recipe’ forphotosynthesis.
Sharing responses
Collate results andconclusions from Activity C1aor C1b about photosynthesis.
Group feedback
In small groups, pupilsdiscuss answers fromActivity C1c.
Word games
In small groups, pupilsprepare four questions aboutthe lesson’s content to askanother group.
Looking ahead
In pairs, pupils suggest howplants get the reactants forphotosynthesis to their leaves.
Review learning� Pupils work in pairs and place all the cards face down. They take it in
turns to turn over two cards and look at them before returning themto face down. They need to remember where they are so that theycan turn up a leaf adaptation with how it helps the leaf tophotosynthesise together later. The person with the most correctpairs wins.
Sharing responses� As a class, ask pupils to share their ideas on what they think will
happen.
� Ask them to explain their predictions.
Group feedback� Pupils share ideas about the role of each part of the leaf from
Activity C2b.
� As a class, use a QX3 microscope and projector to relate pupils’feedback to the different parts of the leaf.
Word game� Initiate a word splat by asking pupils to devise questions that can be
answered by pointing at the key words for the lesson. The key wordsshould be written on the board/OHP.
� Divide the class into two groups and invite a pupil from each groupto stand close to the board/OHP.
� Choose a pupil to ask a question. The pupils by the board/OHP musteach say the word and try to point to it first. The loser choosesanother member of his or her group to stand by the board/OHP.
Looking ahead� Organise the class into groups of three.
� Give each pupil in the group one of the word pairs (see right). Askthem to think about what links/connects the two words.
� Pupils then discuss their ideas with other pupils who have also beengiven that word pair.
� Pupils return to their original group of three. Each group memberthen shares his information with their original group.
Review learning� As a class, pupils describe the path of water through a plant
by completing a flowchart.� Start by drawing a box with ‘Water in the soil’ written in it.� Leave a space and in the last box, write ‘Water in the leaf
cells’.� Pupils should think of what to write in boxes in between
these two to complete the journey of water movementthrough a plant. Draw arrows to link the boxes in aflowchart.
Sharing responses� Collate results and conclusions from Activity C3b.� Focus on the movement of the ink and how that relates to
the slides.� Ensure pupils are clear about the functions of veins in
stems and leaves.
Group feedback� Pupils share ideas from Activity C3a about how root hairs
help the plant take in water and nutrients from the soil.� Ask pupils to use their ideas to design the pipework
connected to a pump for pumping water out of the soil.
Word game� Give each pupil a card containing a question and an
answer. Ask one pupil to stand up and read out just thequestion on their card, then sit down. The pupil who hasan appropriate answer to this question stands up, reads outtheir answer, then asks the question on their card and sitsdown, and so on.
� The game is complete when the pupil who started thegame stands up for a second time to read out the answeron their card. The loop is complete.
� If there are not enough question/answer cards for thewhole class, you may need to make extra copies. Somepupils will have the same question/answer card – the firstone to stand up gets to read their answer and ask theirquestion.
Looking ahead� As a class, pupils discuss why a carrot root is swollen with
stored food, rather than being branched and thin.� If possible, pass around a real carrot for pupils to look at.
➔ Pupil sheet
Equipmentcarrot
Suggested alternative plenary activities (5–10 minutes)
Review learning
As a class, draw a flowchartof water movement in aplant on the board.
Sharing responses
Collate results andconclusions fromActivity C3b.
Group feedback
Share ideas from Activity C3a abouthow root hairs help the plant take inwater and nutrients from the soil.
Word game
Loop game onphotosynthesis tocheck progress.
Looking ahead
As a class, discuss why a carrot rootis swollen with stored food, ratherthan being branched and thin.
Review learning� Pupils play ‘What happens next?’ starting from
photosynthesis happening in a tree.
� Begin the story by saying that photosynthesis happens in atree and produces glucose.
� Ask pupils ‘What happens to the glucose?’
� For each answer they give, reply ‘What happens to it then?’or ‘What happens next?’
Sharing responses� Pupils share findings from activity C4a with the class, to
produce a table on the board of all the class results.
Group feedback� In groups, pupils share their calculations and conclusions
from Activity C4b.
� Emphasise that none of the foods provides as much energyas petrol, but that cooking oil and sugar cane haveadvantages for countries with no petrol supply and becausethey are renewable.
Word game� Pupils write a spider diagram to show how photosynthesis
relates to the production of biomass.
� Take suggestions from individuals to build up the spiderdiagram on the board.
Looking ahead� Give pupils the list of answers.
� Ask them to work in pairs to devise questions for each ofthese answers.
➔ Pupil sheet
Suggested alternative plenary activities (5–10 minutes)
Review learning
Play ‘What happensnext?’ starting fromphotosynthesishappening in a tree.
Sharing responses
Share findings from ActivityC4a to produce a table on theboard of all the group’s results.
Group feedback
In groups, pupils collateresults and conclusionsfrom Activity C4b.
Word game
Pupils write a spiderdiagram to show howphotosynthesis relates tothe production of biomass.
Looking ahead
Give pupils the list of answers. Askthem to work in pairs to devisequestions for each of theseanswers.
C1 Hungry plants1 Clockwise from top right – oxygen, carbon
dioxide, water, light energy, glucose, sunlight.2 a food, leaves
b glucosec oxygend carbon dioxide, water, sunlighte photosynthesis
C2 A food factory1 Clockwise from top right – stomata, waxy
surface, chloroplasts, vein.2 Photosynthesis happens in the … green
chloroplasts.Leaves are broad and flat to … catch as muchsunlight as they can.Leaves have holes called stomata to … let incarbon dioxide and let out oxygen.Leaves have a waxy surface to … stop waterbeing lost.Leaves have veins to … transport water into theleaf.
C3 Don’t dry up!1 From the top – vein, stem, leaf, root, root hairs.2 water – Needed for photosynthesis and to carry
nutrients around the plant.roots – Take in water and nutrients from the soil.They hold the plant firm in the soil.root hairs – Make the surface of the roots biggerso that they can take in water more quickly.veins – Carry water and nutrients all around theplant.nutrients – Help the plant to stay healthy.
3 a Coloured in – the holes in the diagram.b veins
C4 Using plant biomass1 a biomass
b glucosec energy, growthd stored, starche electricity
2 a trueb falsec true
3 corn oil – From corn plants, it contains fat. It isused for food.golden syrup – From sugar cane and is used tomake foods like biscuits.TVP – Protein from vegetables and often eatenby vegetarians.wood – From trees and is used for furniture andbuilding.cotton – From cotton plants and is used to makeclothes.
C5 Spot the difference1 Respiration happens in … every cell of every
animal and plant.Photosynthesis happens in … plants duringthe day.Cutting down the rain forests could make …carbon dioxide levels go up.Through the night and day … both plants andanimals respire.
4 Aimee is trying to find out if all types of light are suitable forphotosynthesis. She is using pondweed and counting thenumber of bubbles it makes per minute with differentlycoloured lights. Her results are shown below.
a Which colour of light is most strongly absorbed duringphotosynthesis?
b With which colour is photosynthesis slowest?
c What gas is in the bubbles coming from the pondweed?
d i Explain how you can tell that white light helpsphotosynthesis.
ii Explain why photosynthesis is slower in white light thanin red or blue light.
e Write down the symbol equation for photosynthesis.
1 The diagram shows the cells in across-section from a leaf.
a What is the name of the structurelabelled E?
b What type of cell is in layer B?
c What is the function (job) ofpart C?
d i A is a waxy layer. What does it do?
ii Explain why this is important.
e Why is structure D green?
f Copy and complete the followingsentences.
i Most leaves are wide and flat because … .
ii Chloroplasts are mostly in the upper surface of a leaf because … .
CORE
2 Look again at the diagram for question 1.
a Explain how the shape and position of the cells in layer B helpsphotosynthesis.
b Other than the shape and position, how can you tell that these cellsare where most photosynthesis takes place?
c i Which gas enters the leaf through point C?
ii Which gas leaves through the same point?
d Explain how the water needed for photosynthesis reaches the leaves.
e Conifers have very narrow leaves, which they keep all year round.Broad-leaved trees develop leaves in spring and lose their leaves inthe autumn. Describe how this affects how broad-leaved trees andconifers photosynthesise.
2 Dandelions have a single ‘tap’ root that goes down a very long way into the soil. Couch grass has a mass of fineroots that spread out just under the surface of the soil.
a i What is the disadvantage of asingle tap root?
ii What is the advantage of a root that goes a long way down into the soil?
b i What is the advantage of having a mass of spreading roots?
ii What is the disadvantage of roots that are all close to the soil surface?
c Both types of roots have tiny root hairs.
i Describe what a root hair cell is like.
ii Explain how root hair cells improve the uptake of water by the plant.
d i What important substances, other than water, are also absorbed by roots?
ii Explain how the roots are able to absorb these substances.
EXTENSION
3 The diagram shows a white rose that has beenspecially treated by the grower. Normal white roses do not have coloured tips to their petals.After it was cut for sale, the rose was placed into a container of blue dye for a while. Then it wastaken out and put back into fresh water.
a i Explain how the blue colour has reachedthe tips of the petals.
ii Why is the blue colour only in the tips of each petal and not all over the whole of each petal?
iii What should the grower do if she wants the petals to have red tips instead of blue tips?
b The petals in the rose need sugars but cannot make it.
i Why can’t the petals make sugars?
ii How do sugars get to the petals?
c Give a reason why all cells need water, other than for photosynthesis.
Type of biomass Water temperature Water temperature at start in °C after burning in °C
Sunflower seeds 16 48
Straw 18 37
i Which type of biomass provided the most energy?
ii Explain how you can tell.
d Leroy looked up the amounts of energy from his two types ofbiomass on the Internet. His experiments gave smaller amounts ofenergy than the website figures. Suggest why Leroy’s results were too low.
C-Homework.qxd 07-Jun-04 2:00 PM Page 7
C4 HomeworkUsing plant biomass (continued)
CORE
2 Power stations burn both biomass and fossil fuels to generate electricity.
a What type of energy is stored in both biomass and fossil fuels?
b Biomass is often described as a renewable energy resource. Explainwhat is meant by ‘renewable energy resource’.
c Give one advantage of using biomass instead of fossil fuels.
d What are the products when both types of fuel are burnt?
e Explain why using these fuels is bad for the environment.
3 a Photosynthesis produces glucose. Name two ways that plants use the glucose.
b Some plants store the glucose in their roots. In what form is it stored?
c Explain why they store some of the glucose in this way.
EXTENSION
4 a In many plants, much of the glucose from photosynthesis isconverted to cellulose. Give one useful product that consists of cellulose.
b Explain why cellulose is important to plants.
5 Sandy did an experiment to find out whatsubstances form the biomass of a geraniumleaf. The leaf she chose was green in thecentre and white around the edges. Thediagram shows her leaf.
Sandy boiled her leaf in alcohol to removethe green colouring.
a What substance should Sandy now putonto the leaf to find out if it containedstarch?
b Describe what the leaf would look like after Sandy put this substance onto the leaf.
c Explain why the leaf gave these results.
d How would Sandy’s results have been different if the geranium had been in the dark for several days, before she tested the leaf?
A Carbon dioxide and water 1 only when it is light.react during photosynthesis
B Plants respire 2 to make carbon dioxide and water.
C Plants photosynthesise 3 during the night.
D During respiration the products 4 plants break down their sugars to of photosynthesis react get energy.
E Carbon dioxide is released from 5 all the time.plants through the stomata
F During respiration 6 to make glucose and oxygen.
ii What are the two other things that plants need when they photosynthesise?
b Write down the word equation for respiration.
CORE
2 The graph shows the levels of carbon dioxide and oxygen in Mrs Green’s bedroom over a 24 hour period in December. She likes to have lots of houseplants in her bedroom. She keeps her windows closed during the winter.
midnightmidday0
5
10
15
20
25
A
B
% o
f gas
in t
he a
ir
C-Homework.qxd 07-Jun-04 2:00 PM Page 9
C5 HomeworkSpot the difference (continued)
a i Which line shows the level of carbon dioxide?
ii Both Mrs Green and her houseplants are responsible for the levelof carbon dioxide. Explain why the carbon dioxide graph has theshape shown.
iii How would the carbon dioxide graph be different if Mrs Greenhad no houseplants in her room?
iv How will the carbon dioxide graph be different when Mrs Greenis on a winter holiday?
b The level of oxygen during the day in Mrs Green’s bedroom is higherthan in most bedrooms in December. Explain why it is higher.
c Mrs Green’s neighbour says that Mrs Green should open a bedroomwindow every night. Explain why this is a good idea.
EXTENSION
3 a i Write down the symbol equation for photosynthesis.
ii How is the equation for respiration related to the one you havejust written for photosynthesis?
b Explain why photosynthesis is vital for animals to survive.
c Describe how an atom of carbon, that was once part of a dinosaur,could end up on your plate in a sausage.
1 A – False; B – False; C – False; D – True; E – True. 51 mark for each correct response.
2 a Underscores are pupil response. Accept equivalent responses.Photosynthesis happens better during the summer because there ismore sunlight. 1
b The reactants that plants use when they do photosynthesis are carbon dioxide and water 1
c Plants need the Sun because they need light energy to do photosynthesis 1
Total for Help 8
COREQuestion Answer Mark
3 a Oxygen 1
b Carbon dioxide 1
c i When it is light/during the day. 1
ii Plants need light for photosynthesis. 1
d Plants need water from the soil for photosynthesis. 1
e i It will decrease to nothing/there will be none left. 1
ii There is no carbon dioxide left in the container and 1no more can get in because of the rubber seal, 1so the plant cannot photosynthesise any more. 1
iii There would be no light for photosynthesisso the green colour would be lost from the leaves. 1
Total for Core 10
EXTENSIONQuestion Answer Mark
4 a Blue 1
b Green 1
c Oxygen 1
d i There is a reasonable number of bubbles/bubbles are beingproduced/oxygen is being produced. 1
ii White light contains all the colours of the spectrum 1so the amount of blue and red light is less than with the pure colours. 1
e 6CO2 + 6H2O C6H12O6 + 6O2 2Award one mark for correct formulae and one for balancing.
c To let air/gases/carbon dioxide into the leaf or to let oxygen out of the leaf. 1
d i Stops the leaf from drying out. 1
ii Water is needed for photosynthesis. 1
e It contains chlorophyll. 1
f i Most leaves are wide and flat because this lets them absorb lots of light. 1Underscore is pupil response. Accept equivalent responses.
ii Chloroplasts are mostly in the upper surface of a leaf because theycan get the most sunlight there for photosynthesis. Underscore is 1pupil response. Accept equivalent responses.
Total for Help 8
COREQuestion Answer Mark
2 a Pack closer together so absorb more light; at the top ofthe leaf so nearest to the Sun. 2
b They have the most chloroplasts. 1
c i Air/carbon dioxide. 1
ii Oxygen 1
d From roots in the soil 1through the veins. 1
e Broad-leaved plants photosynthesise a lot in spring and summer. 1Narrow-leaved plants cannot photosynthesise as much in spring and summer 1so they have to be able to photosynthesise all year round. 1Accept equivalent alternative responses.
Total for Core 10
EXTENSIONQuestion Answer Mark
3 a To make the food they need for life processes. 1
b i They have no chlorophyll/chloroplasts. 1
ii They get their food directly from other vegetation. 1
4 a 12 hours. 1
b Clouds/it was raining. Accept other sensible suggestions. 1
1 a Any three from: same volume of water; same mass of biomass burnt;water starts at the same temperature; flame same distance from boilingtube; protect from draughts. 3
b Any two from: point the tube away from people; the tube is clamped;the apparatus is away from the edge of the bench; the tube is over thebase of the stand. Do not accept references to personal protection, such as 2eye protection or tied-back hair etc.
c i Sunflower seeds. 1
ii Higher temperature change (32 °C). 1
d One appropriate point from: not all the heat went into the water; thefuel did not burn properly; some of the heat went into the glass boiling tube. 1
Total for Help 8
COREQuestion Answer Mark
2 a Chemical energy. 1
b They can be easily replaced/more can be produced. 1Do not accept references to re-use.
c Will not run out/can grow some more quickly. 1
d Carbon dioxide and water. 1
e Carbon dioxide is a pollutant 1responsible for global warming/involved in the greenhouse effect. 1
3 a As the fuel for respiration. 1To make new plant cells/to grow. 1
b Starch 1
c So they can use it as their food source later. 1
Total for Core 10
EXTENSIONQuestion Answer Mark
4 a Wood/cotton. Accept other suitable responses. 1
b It forms their cell walls/provides strength/provides support. 1
5 a Iodine solution. Response must refer to solution. 1
b The edges would be yellow/would not be blue-black/would not change. 1The centre part would be blue-black. 1
c Photosynthesis needs chlorophyll. 1There was chlorophyll in the centre part of the leaf but not in the edges. 1
d None of the leaf would turn blue-black with iodine solution. 1
1 a i Correct matches are: A – 6; B – 5; C – 1; D – 2; E – 3; F – 4. 55 or 6 correct = 5 marks; 4 correct = 4 marks etc.
ii Chlorophyll and sunlight. 2
b sugar/glucose + oxygen carbon dioxide + water 1
Total for Help 8
COREQuestion Answer Mark
2 a i Line A. 1
ii Both are respiring at night 1which produces carbon dioxide; 1but no photosynthesis is happening at night. 1
iii It would still be higher at night but not so high. 1
iv It will be much lower. 1
b All the plants are photosynthesising 1which gives off oxygen. 1
c It would allow fresh air in to replace the oxygen used up during respiration 1and it would enable some of the carbon dioxide to escape. 1
Total for Core 10
EXTENSIONQuestion Answer Mark
3 a i 6CO2 + 6H2O C6H12O6 + 6O2Award 1 mark for correct formulae and 1 mark for balancing. 2
ii It is the same thing in reverse. 1
b Animals need glucose for respiration 1but they cannot make it by photosynthesis 1so they eat plants that photosynthesise. 1
c The dinosaur breathed out carbon dioxide into the air. 1Carbon dioxide from the air goes into the plant that is inthe sausage/eaten by the pig that went into the sausage. 1
Total for Extension 8
C-Homework.qxd 07-Jun-04 2:00 PM Page 15
C Test yourselfPlants and photosynthesis
1 Complete these sentences by crossing out the words that are wrong.
a Plants do/do not take in soil from the ground as they grow.
b During photosynthesis plants take in water through their leaves/roots.
c Plants also take in carbon dioxide/oxygen to make glucose.
2 Complete the following word equation for photosynthesis.
+ water → + oxygen
3 The following steps were carried out by a student who was doing an experiment to see if light is needed for photosynthesis. The steps are in the wrong order. Write a number next to each step to show its correct order.
Boil the leaf in hot alcohol. Place the leaf in boiling water.
Cover part of leaf with black paper. Remove the black paper.
Add iodine solution to the leaf. Make a note of whether the
Leave the leaf in the light for 24 hours.iodine turns black.
4 Draw lines to match each process with the correct reason for doing it.
Process Reason
boil the leaf in water � � turns black if starch is present
boil the leaf in alcohol � � breaks down the cell walls
add iodine solution � � dissolves out the chlorophyll
5 Complete the sentences below. Choose from these words to fill in the gaps. You may use each word once, more than once, or not at all.
As the amount of light increases, the rate of photosynthesis .
The rate of photosynthesis in some water plants can be determined by
counting the number of bubbles given off.
Plants use a green pigment called to carry out the process of photosynthesis.
Most photosynthesis takes place in the cells in the
cells through which water is absorbed and nutrients pass into the
plant
air spaces containing oxygen that the roots need for respiration
glucose (the source of all biomass in the
plant) made here by photosynthesis using water from the roots and carbon dioxide
from the air
carries water up the plant to the leaves for
photosynthesis
Test-Qust.qxd 6/25/2004 10:32 AM Page 9
C Test yourselfPlants and photosynthesis (continued)
8 Complete the sentences below to describe the effects of plants on the environment. Choose from these words to fill in the gaps. You may use each word once, more than once, or not at all.
Photosynthesis and respiration together ensure that the level of
carbon dioxide in the atmosphere is .
However, because modern societies burn a lot of fuels, the level of
carbon dioxide is .
Cutting down and burning rainforest is also responsible for
levels of carbon dioxide. Only by reducing
the amount of fuel that we burn and conserving the rainforests
can we ensure levels of carbon dioxide.
Plants release energy from food by .
Humans and animals rely on to use carbon dioxide and produce oxygen for them to respire.
9 The graph shows both the rate of respiration and the rate of photosynthesis in a flowering plant.
a During what period of time is photosynthesis faster than respiration?
b At which two times does the rate of photosynthesis equal the rate
1 Complete these sentences by crossing out the words that are wrong.
a Plants do/do not take in soil from the ground as they grow.
b During photosynthesis plants take in water through their leaves/roots.
c Plants also take in carbon dioxide/oxygen to make glucose.
2 Complete the following word equation for photosynthesis.
+ water → + oxygen
3 The following steps were carried out by a student who was doing an experiment to see if light is needed for photosynthesis. The steps are in the wrong order. Write a number next to each step to show its correct order.
Boil the leaf in hot alcohol. Place the leaf in boiling water.
Cover part of leaf with black paper. Remove the black paper.
Add iodine solution to the leaf. Make a note of whether the
Leave the leaf in the light for 24 hours.iodine turns black.
4 Draw lines to match each process with the correct reason for doing it.
Process Reason
boil the leaf in water � � turns black if starch is present
boil the leaf in alcohol � � breaks down the cell walls
add iodine solution � � dissolves out the chlorophyll
5 Complete the sentences below. Choose from these words to fill in the gaps. You may use each word once, more than once, or not at all.
As the amount of light increases, the rate of photosynthesis .
The rate of photosynthesis in some water plants can be determined by
counting the number of bubbles given off.
Plants use a green pigment called to carry out the process of photosynthesis.
Most photosynthesis takes place in the cells in the
part of the leaf, because they receive more .light
air spaces containing oxygen that the roots need for
respiration
glucose (the source of all biomass in the plant) made here by photosynthesis using
water from the roots and carbon
dioxide from the air
carries water up the plant to the leaves for photosynthesis
branching and a large surface area
for taking in water
cells through which water is absorbed and nutrients pass
into the plant
Test-Ans.qxd 16-Jun-04 2:54 PM Page 9
CTest yourself
AnswersPlants and photosynthesis (continued)
8 Complete the sentences below to describe the effects of plants on the environment. Choose from these words to fill in the gaps. You may use each word once, more than once, or not at all.
Photosynthesis and respiration together ensure that the level of
carbon dioxide in the atmosphere is .
However, because modern societies burn a lot of fuels, the level of
carbon dioxide is .
Cutting down and burning rainforest is also responsible for
levels of carbon dioxide. Only by reducing
the amount of fuel that we burn and conserving the rainforests
can we ensure levels of carbon dioxide.
Plants release energy from food by .
Humans and animals rely on to use carbon dioxide and produce oxygen for them to respire.
9 The graph shows both the rate of respiration and the rate of photosynthesis in a flowering plant.
a During what period of time is photosynthesis faster than respiration?
b At which two times does the rate of photosynthesis equal the rate
1 Write out two things from the following list that a plant uses to make food.
• starch • glucose• water • light• oxygen 2 marks
2 Look at the list below. From where does a plant obtain:
a carbon dioxide? b water? 2 marks
3 In which part of the plant does each of the following processes take place?
a absorption of water b photosynthesis 2 marks
4 Rita’s class was asked to write down the word equation for photosynthesis.
Four of the different answers produced by the class are listed below.
A oxygen + glucose → carbon dioxide + waterB oxygen + water → carbon dioxide + glucoseC carbon dioxide + water → glucose + oxygenD oxygen + carbon dioxide → water + glucose
a Which was the correct equation for photosynthesis? 1 mark
b Which was the correct equation for respiration? 1 mark
5 Peter examined the leaves of a plant he had grown.He noticed the leaf had various features.Explain how each of the features below enables leaves to carry out their function.
a a large surface area b green 2 marks
6 When the plant had grown, Peter carefully removed it from the soil.He looked at the root structure and noticed several features.
a Explain how each of the features below enables roots to absorb water. 3 marks
i a branching structureii a large deep rootiii many tiny, long thin root hairs
b Why do plants need to take up nitrates through their roots? 1 mark
7 Plants produce biomass. Biomass can be useful to us in many different ways. One example is sugar from sugar cane.
a Name one other use of biomass. 1 mark
b What is the name of the process by which a plant produces biomass? 1 mark
8 Respiration is the process in which living things break down molecules of glucose to release energy.
a Four different statements about the difference between photosynthesis and respiration are given below. Which two are correct? 2 marks
A Photosynthesis uses light energy, respiration releases energy.B Photosynthesis uses water and oxygen, respiration releases water and oxygen.C Photosynthesis does not need chlorophyll, respiration needs chlorophyll.D Photosynthesis produces glucose, respiration uses glucose.
b State the source of the energy for the process of photosynthesis. 1 mark
c Describe how you would test a sample of biomass to show the presence of starch. 1 mark
9 Katie has set up this experiment:
She has put hydrogencarbonate indicator into each test tube. This indicator changescolour when the amount of carbon dioxide in the test tube changes. The colourchanges of the indicator are shown in this table:
1 Peter examined the leaves of a plant he had grown. He noticed the leaf had various features.
Explain how each of the features below enables leaves to carry out their function.
a large surface area 1 mark
b green 1 mark
2 When the plant had grown, Peter carefully removed it from the soil.
He looked at the root structure and noticed several features.
a Explain how each of the features below enables roots to carry out their function. 2 marks
i a branching structureii tiny root hairs
b Why do plants need to take up nitrates through their roots? 1 mark
3 Rita’s class was asked to write down the word equation for photosynthesis.
Four of the different answers produced by the class are listed below.
A oxygen + glucose → carbon dioxide + waterB oxygen + water → carbon dioxide + glucoseC carbon dioxide + water → glucose + oxygenD oxygen + carbon dioxide → water + glucose
a Which was the correct equation for photosynthesis? 1 mark
b Which was the correct equation for respiration? 1 mark
c Raymond did an experiment to measure what two substances were absorbed by a plant in order to photosynthesise. To explain what happens in photosynthesis, he decided to write a symbol equation. He wrote down some of the chemical formulae, but failed to complete the equation.
4 Plants produce biomass. Biomass can be useful to us in many different ways. One example is sugar from sugar cane.
a Name one other use of biomass. 1 mark
b What is the name of the process by which a plant produces biomass? 1 mark
5 Respiration is the process in which living things break down complex molecules such as starch to release energy.
a Describe two ways in which this process differs from photosynthesis. 2 marks
b State the source of the energy for the process of photosynthesis. 1 mark
c Describe how you would test a sample of biomass to show the presence of starch. 1 mark
6 a Plant cells in the root are adapted to absorb water from their immediatesurroundings.
Explain how having a long thin hair-like shape helps a root to absorb water. 1 mark
b Palisade cells in the leaf are adapted for photosynthesis.
Describe two features that help a palisade cell to photosynthesise. 2 marks
7 Plants require carbon dioxide for photosynthesis and produce oxygen as a waste product. The carbon dioxide diffuses into the leaf through small holes on the under surface and oxygen diffuses out.
Explain what effect you think the following changes would have on the rate at which photosynthesis takes place:
a an increase in the level of atmospheric carbon dioxide 1 mark
b a decrease in the amount of chlorophyll in the leaf cells. 1 mark
She has put hydrogencarbonate indicator into each test tube. This indicator changes colour when the amount of carbon dioxide in the test tube changes. The colour changes of the indicator are shown in this table:
Katie left the test tubes in sunlight for two hours. These are her results:
a David said that 10 minutes should be long enough, but Katie said he was wrong. Why did she say this? 1 mark
b Katie says that the results of test tube B shows that plants always use up carbon dioxide. Is this a fair conclusion to make? Give a reason. 1 mark
c Katie has another test tube, identical to B. What could she do with it to check her conclusion? 1 mark
d How could Katie improve the reliability of her results in her experiment? Give two ways. 2 marks
4 a C or carbon dioxide + water → glucose + oxygen 1 6
b A or oxygen + glucose → carbon dioxide + water 1 6
5 a Can absorb more carbon dioxide or light or get rid of more oxygen. 1 5
b Contains chlorophyll to trap energy from sunlight or contains chlorophyll for photosynthesis. 1 5
6 a i To reach many parts of the soil. 1 5ii To get to water deep down or to reach the water table. 1 5iii Give a large surface area for absorption. 1 5
b To grow or make proteins. 1 5
7 a Any suitable example, e.g. wood for burning. 1 5
b Photosynthesis 1 6
8 a A and D. 1, 1 6
b Light or sunlight or the Sun. 1 5
c Add iodine solution – the starch in biomass turns black. 1 5
9 a Amount of carbon dioxide. 1 4
b i Make sure it was the organisms, not some other factor, causing the effect. 1 5
ii Same amount of liquid/indicator as other tubes. 1 5
c i Need to leave enough time for the experiment to stabilise/snails and plants respire slowly. 1 6
1 a Can absorb more carbon dioxide or light or get rid of more oxygen. 1 5
b Contains chlorophyll to trap energy from sunlight orcontains chlorophyll for photosynthesis. 1 5
2 a i To reach many parts of the soil. 1 5ii Give a large surface area for absorption. 1 5
b To grow or make proteins. 1 5
3 a C or carbon dioxide + water → glucose + oxygen 1 6
b A or oxygen + glucose → carbon dioxide + water 1 6
c 6H2O + 6CO2 → C6H12O6 + 6O2 (One mark for H2O and O2 in correctspace, one mark for balancing correctly, no marks for only one correctwithout balancing.) 2 7
4 a Any suitable example, e.g. wood for burning. 1 5
b Photosynthesis 1 6
5 a Any two from: 2 6Photosynthesis uses light energy or water or carbon dioxide; respiration releases energy or produces water or produces carbon dioxide.Photosynthesis produces glucose or oxygen; respiration uses glucose or oxygen.Photosynthesis needs chlorophyll; respiration does not need chlorophyll.
b Light or sunlight or the Sun. 1 6
c Add iodine solution – the starch in biomass turns black. 1 6
6 a Gives a large surface area compared with its volume. 1 7
b Lots of chloroplasts. 1 7Cells situated near upper surface of leaf. 1 7
7 a Rate of photosynthesis would increase (more reactant for the reaction). 1 7*
b Rate of photosynthesis would decrease. 1 7*
8 a Need to leave enough time for the experiment to stabilise/snails and plants respire slowly. 1 6
b No, she has only tested it in the light. 1 6
c Repeat the experiment, keeping the tube in the dark. 1 6
d Have an identical control tube but with no organisms. 1 7Repeat the experiment with fresh snails and waterweed. 1 7
C1 Hungry plantsGreena Andrew and Jenny.b i Carbon dioxide and water.
ii Glucose and oxygen.c The living room.d The plant in the living room can
photosynthesise more quickly because there ismore light there.
1 a Plants make food by a process calledphotosynthesis.
b Plants get light energy from the Sun.c Most photosynthesis happens in the leaves.d Photosynthesis produces sugar and oxygen.
2 a Photosynthesis would stop.b Photosynthesis would stop.
3 There would not be enough oxygen and toomuch carbon dioxide would accumulate tosupport human life.
Reda Andrew and Jenny.b Do experiments in which you stopped, in turn,
sunlight, carbon dioxide and water fromreaching the plant.
c The mass of the tree increased much more thanthe loss of mass in the soil. This tells us that thetree gained its mass from materials outside the soil.
d From the carbon dioxide and water in the air.e The plant in the living room can
photosynthesise more quickly because there ismore light there.
f Photosynthesis stopped between (about) 18:00and 05:00 hours. The carbon dioxide levelstayed high and the oxygen level stayed lowduring these hours.
g Between (about) 08:00 and 15:00 hours.h Between 18:00 and 05:00 hours.1 To produce the food they need to grow.2 There would not be enough oxygen in the
atmosphere without plants to support humanlife. Too much carbon dioxide would accumulateto support human life without plants.
3 a There were fewer bubbles produced each minute.b The speed of photosynthesis decreased.c The plant is synthesising as fast as it can.
C2 A food factoryGreena A large surface area gathers more light. Being thin
allows the light to penetrate into the solar cell.b So they will be able to use a large amount of the
Sun’s energy.c So that the sunlight will penetrate into the leaf.d oxygene More sunlight can reach the cells near the top
where photosynthesis occurs.1 Photosynthesis happens in the chloroplasts in
the leaf. Leaves are broad and flat to take in a lot
of light energy. Leaves have holes in to letgases in and out. Leaves have a waxy topsurface to stop water being lost.
2 a chloroplastsb They can pack together closely making sure
they catch as much light as possible.3 The carbon dioxide for photosynthesis goes into
the leaf through the stomata. The oxygen madeby photosynthesis moves out of the palisadecells, into the stomata and then out of the leafand into the air.
Reda They are both broad and thin.b They need to gather more light in the shade so
they have broader leaves.c So that the sunlight can penetrate into the
palisade cells.d The veins transport water around the leaf.e The carbon dioxide from the air passes through
the guard cells into the stoma and then diffusesinto the palisade cells where it is used by thechloroplasts to make glucose and oxygen.
1 Large, broad and thin2 a They contain chloroplasts.
b They have a large surface area so that everycell receives as much sunlight as possible.
c To let the gases move around the leaf.3 a They allow gases to pass in and out of the
leaf from the atmosphere.b They change shape to open or close each
stoma. By doing this they control theamount of carbon dioxide and oxygen thatgoes in and out of the leaf.
4 a Only in the cells that contain chlorophylltowards the centre of the leaf.
b Food dissolves in water and is carriedthrough the veins to other parts of the plantso the plant’s cells can use it.
C3 Don’t dry up!Greena Water is needed for photosynthesis, it carries
nutrients around the plant and it keeps theplant upright.
b They keep the plant healthy.1 a To be used in photosynthesis and to carry
nutrients around to all cells in the plant.b They help the plant to stay healthy and
photosynthesise more efficiently.2 a To take in water and nutrients from the soil.
To hold the plant firm in the soil.b They have a large surface area.
3 Individual answers.
Reda Water is used in photosynthesis. It carries
nutrients around the plants through the veins sothat all cells get the food they need to stay alive.
C Book answersPlants and photosynthesis (continued)
b i Root hair cells are specialised cells that stickinto the soil, giving a large surface area,which helps the roots take in water from thesoil more quickly.
c i The plant will wilt.ii The root cells won’t get any oxygen and
will die.d All the plant’s cells need glucose for respiration.1 a A water droplet follows the route from the
soil into the root hair cells, root, stem, veins,spongy layer, palisade cell.
b To carry out photosynthesis and to transportnutrients around the leaf.
2 a So that they get water from a long distancefrom the plant and so that they have a largesurface area to absorb water.
b So that they can absorb water quickly.c The hairs are very fine and poke into the soil
giving a large surface area.
C4 Using plant biomassGreena biomassb From the Sun, from glucose used to make plant
materials and from the mass of animal material.c For eating, for building houses and furniture, for
making clothes, etc.1 The total mass of a living thing, not ... including
water, is called the biomass.Starch ... is made from glucose.Biomass can be stored in ... the roots, stem orleaves.Photosynthesis makes glucose which ... makesother substances.
2 To make leaves, stems, flowers, seeds and roots.3 Individual answers.
Reda Fossil fuels, oil, coal and gas.b biomassc Protein, fat, carbohydrate, vitamins and minerals.d For eating, for building houses and furniture, for
making clothes, etc.1 Biomass is the total mass of plant or animal
material, not including water.2 To help them survive.3 Individual answers.4 a Any four of: leaves, stems, flowers, seeds, roots.
b The Sun.5 The glucose made in a plant by photosynthesis
is joined together to make starch. The starch isstored in roots, stems and leaves to help themsurvive into the next year.
C5 Spot the differenceGreena They are the same.b i In every cell of the plant.
ii In the leaves.
c Carbon dioxide.d oxygene Trees which have been cut down will not use the
carbon dioxide for photosynthesis. The carbondioxide levels will go up as the gas accumulatesin the atmosphere.
f Oxygen is needed by plants and animals forrespiration.
1 a Respiration happens in every cell of everyanimal and plant.
b Cutting down rainforests may make carbondioxide levels go up in the air around theworld.
c Photosynthesis happens in plants duringthe day when it is light.
d Respiration happens during the night andthe day.
2 Day Nightgives out carbon dioxide � �takes in carbon dioxide � ✗gives out oxygen � ✗takes in oxygen � �
3 Because they give out carbon dioxide gas onlywhich is not healthy for a person recoveringfrom an illness.
Reda i The reactants in photosynthesis are the same
as the products in respiration.ii Photosynthesis uses energy but in respiration
energy is released.b Plants photosynthesise during the day and
respire all the time. Carbon dioxide is given outall the time so respiration must be happeningall of the time.
c Carbon dioxide.d oxygen
The carbon dioxide levels went up very slowlyin the 1700s but they went up very quickly inthe 1900s.
e They would decrease.1 a Respiration occurs all of the time in living
plants and animals.b Respiration occurs in plants all of the time.
2 Day Nightgives out carbon dioxide � �takes in carbon dioxide � ✗gives out oxygen � ✗takes in oxygen � �
3 Because they give out carbon dioxide gas onlywhich is not healthy for a person recoveringfrom an illness.
4 The level of carbon dioxide increases at nightand decreases during the day. The oxygen levelincreases during the day and decreases at night.
5 a The oxygen level will decrease and thecarbon dioxide level increase.
b The oxygen level will increase and the carbondioxide level will decrease.