Transcript
B4LESSON 1 & 2
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PROCESSES OF LIFE
ALIVE OR NOT ALIVE?YOUR TASK
Ask each student to name one living thing and one non living thing. Write down
answers under the column headings "Living" and "Non living".
Next Task Develop criteria to decide if something is
living or non-living
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FEATURES OF LIVING THINGS
Your Tasklist the basic processes of life carried
out by all living things
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LESSON 1
Lesson Overview
In this lesson, students learn about the characteristics that distinguish living
things from non-living things. By examining seed Beetles students gather evidence and develop criteria to decide if
something is living or non living.
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IS IT ALIVE?
In science, living is used to describe anything that is or has ever been alive Examples dog, flower, seed, road kill, log Non living is used to describe anything that is not now nor has ever been alive Examples include rock, mountain, glass, wristwatch.
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WHAT MAKES YOU A LIVING THING?It is important for students begin to erode their misconceptions about living and non living things and to begin to understand that all living things grow, breathe, reproduce, excrete, respond to stimuli, and have similar basic needs like nourishment. All living things are made up of cells.
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MRS GREN
The following are features of all living things:
Movement, Respiration, Sensing, Growth,Reproduction, Excretion and Nutrition
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Planning Your InvestigationChallenge students to develop their own methods to test the preferences of seed
beetles.
Plan an investigation to test your ideaswww.sciencetutors.zoomshare.com
PLANNING YOUR INVESTIGATIONStudents plan and complete Activity AB4.1.1
Can seed beetles sense gravity?
YOUR TASK is to demonstrate that simple organisms, such as seed beetles, are able to sense their surroundings.
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ANALYSING RESULTS
In experiments the measurements are likely to vary. Students could be asked to suggest why they get different values. Introduce the terms
1. Repeatability and 2. Reproducibility.
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EVALUATIONCan you comment on any improvements you could make to theThe way you did your test/investigationThe accuracy of your readings/resultsWould you get the same results if you were to
repeat your investigation again? Why?Are your results enough to draw a firm conclusion?
Explain why? Can you suggest any further work to extend your
investigation?
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GCSE MAY 2009 Q2
ENZYMES AND pH
Learning outcomes:
At the end of this unit you should be able to
1.Summarise the role of enzymes in living organisms
2.Describe enzyme action in terms of active site shape
3.Describe the effect of pH on enzyme activity
RECAP ENZYMES FROM PREVIOUS LESSON MODULE 1
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Quick Quiz
What are enzymes? What is the importance of enzymes for
living beings?
What are the factors affecting the speed of Enzymes
Turn to page 14-15 and 16-17 for answers. Remember you have 5 minutes to complete this task.
What Are Enzymes?
Enzymes are proteins that are catalysts of chemical reactions.
Catalyst are substances that increases the speed of a chemical reaction.
Factors Affecting The Speed Of Enzymes
What are the main factors that alter the speed of enzymatic
reactions?
Factors Affecting The Speed Of Enzymes
What are the main factors that alter the speed of enzymatic reactions?
The main factors that change the speed of enzymatic reactions are temperature, pH and
substrate concentration (quantity).
YOUR TASK
What is meant by substrates of
enzymatic reactions?
DEMO EXPERIMENT
Perform a brief demonstration to show the effect of catalase (liver or potato)
on hydrogen peroxide. Discuss the role of catalase in cells.
Students complete Activity AB4.2.1 Catalase to collect oxygen from a known concentration of hydrogen peroxide and yeast at different pHs.Students could pool their results and calculate mean values. Discuss how the mean gives a good estimate of the true value.
HINT ON DEMO EXPERIMENT
Students repeat the reaction three times to show the effects of acid, alkali and neutral pH. This gives a qualitative indication of the effect of pH on enzyme action. At this stage it is sufficient to deal with pH in terms of acidic conditions, alkali conditions and neutral conditions.
REACTANTS AND PRODUCTS
Introduce the terms ‘reactants’ and ‘products’ in the context of this particular enzyme.
Conclusion: pH influences enzyme activity.
ENZYMES - SPEEDING UP
How does the enzyme speed up the reaction? Students look at the first two screens of Animation IB4.2.4 Enzymes to introduce the idea of the lock-and-key model.Students complete Activity AB4.2.2 Lock-and-key model using Textbook Section B and Animation IB4.2.4 Enzymes.
Differentiation
To gather more quantitative results, students can be given yeast suspensions covering a range of specific pH values so that they can obtain results to plot a graph of activity against pH.
H: Use Activity AB4.2.2 sheet 1 Lock-and-key model.F: Use Activity AB4.2.2 sheet 2 Lock-and-key model.
GAS EXCHANGE -DIFFUSION
Learning OutcomeTo describe how molecules get into
and out of leavesTo explain the processes of diffusion
INPUT AND OUTPUT
List the inputs and outputs needed by living organisms (food, gas exchange, wastes, etc.).
INPUT AND OUTPUT
List the inputs and outputs needed by living organisms (food, gas exchange, wastes, etc.).
Introduce diffusion as the way molecules get into and out of
cells.
YOUR TASK
Demonstrate diffusion in air by spraying a small amount of air freshener at the front of the class. (Note: a) Have students raise their hands when they smell the air freshener. Time how long it takes to reach the back of the class.
Fill the results into the table in Activity AB4.5.1 Diffusion and calculate the speed of diffusion in air. Discuss how the molecules spread from an area of high concentration to low concentration.
TRANSPORTATION IN CELLS
You could use the diffusion section of Animation IB4.5.4 Transport across cell
membranes to illustrate diffusion across cell membranes. (Note: b)
PRACTICAL ACTIVITY
Students complete Activity AB4.5.1
Diffusion with an investigation of
diffusion in water and in a gel.
PRACTICAL ACTIVITY
Students complete Activity AB4.5.2 Gas exchange in plants:
Looking at stomata in leaves Students produce nail varnish imprints of the upper and lower surface of a leaf, allowing them to observe stomata and compare the numbers in each surface.
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