Year 8 Yearly Science Notes-Tang's USB

8/4/2019 Year 8 Yearly Science Notes-Tang's USB

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Year 8 Half Yearly Science Notes 2009

1. Plan Investigations and identify the type of information or data that needs to be collected and

why

- Scientists ask What, why and how?

-Research normally starts with observations

-An observation is either qualitative or quantitative

-Qualitative: described or written in words

-Quantitative: measured and stated as numbers

2. Identify the variables and what need to be controlled

-The aim is what is being tested

-A variable is anything that changes within an experiment

3. Identify the dependent and independent variables that need to be controlled

-The independent variable is what is being changed

-The controlled variables are kept the same

-The dependent variable is the result that is measured/recorded

-The dependant variable depends upon what we change.

4. Observe and interpret what happens when a candle burns in a sealed space

-The height of the water level rose with each candle burnt

-The variable which probably had the most effect on the change in water level was the number of

candles

-The controlled variables are the height of the glass, the amount of plasticine and the volume and

depth of water

-Reasons that the water level rose in the jar are 1) As the candle burnt, the heat caused oxygen to

evaporate and 2) the wax dissolved into the water

5. Investigate the effect of salt on the boiling point of water

-Cooks add salt to water because it speeds up the time it takes for water to boil

6. Outline the nature of the scientific method


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10. Identify and describe the nature of the common errors: parallax, reading errors, instrument

errors, reaction time

-Common errors are parallax error, reading error, instrument errors and human reaction time

-A parallax error is when a measurement is read at different angles

-A reading error is when measurementsfall between the markings on a measuring device

-An instrument error is when the instrument isfaultye.g. a metal ruler expanding on a hot day

-Human reaction timeis when we cant react fast enough to take a measurement


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11. Describe how the reliability of an investigation can be increased

-We can give and take when the exact measurement cannot be obtained. This is written as

when is how much you give or take

12. Describe how the accuracy of an investigation can be increased

-To improve the accuracy of a measurement a mean or average can be taken

13. Investigate the effects of changing the mass, length, angle on the period of a pendulum

-A pendulum is a mass (called a bob) attached to a rod, chain or rope, which swings back and forth

repeatedly

-The period of a pendulum is the time it takes to complete one entire swing, back and forth

-Variables that affect the period are the length of the string, the mass of the bob, the angle of the

bob from vertical at the start

14. Analyse results graphically and draw the line of best fit

-Connecting the points up dot-to-dot suggests that there were no errors in the experiment

-Points instead should be joined with a line or curve of best fit through the centre of the points

-Extrapolation is the continuing of the shape of the line or curve topredict extra results

-Graphs of straight lines or smooth curves indicate a pattern, rule or relationship between the

tested variables

15. Write a scientific report using science conventions

-The following must be included in a report: heading,aim, hypothesis (optional), equipment,

method, results and observations, discussion or analysis, conclusion and bibliography


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-Data is usually tabulated

-Line graphs can be used to predict patterns and measurements

16. Use appropriate units

-Scientific measurements are based on the metric system

-Length is measured in metres, mass in grams and volume in litres

-Other units such as newtons for weight and force andjoules for energy depend on these units

(Start Chapter 2: Atoms)

17. Distinguish between an element and a compound

-An element is an absolutely pure substance that cannot be broken down into other substances

-An atom is the smallestpiece of a substance that is still a substance

-A compound consists of a number of identical molecules or a lattice (atoms)joined together

18. Distinguish between metals and non-metals

-Of the 106 known elements, 84 are metals and 22 are non-metals


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19. Identify three metals and list their uses

Example only:

1. Aluminium Cooking utensils

2. Copper Electrical wires, plumbing pipes

3. Mercury Thermometers

20. List the characteristics of a mixture

-A mixture contains two or more substances (elements or compounds) mixed together

-The substances in mixtures are not bonded together; no new substance is formed

-i.e. Mixtures:

Contain two or more substances mixed together

Do not bond

Do not form a new substance

21. Write chemical formulae for oxygen, ozone, methane, glucose, hydrogen chloride

-Oxygen: O2

-Ozone: O3

-Methane: CH4


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-Glucose: C6H12O6

-Hydrogen chloride: HCl

22. Identify symbols of common elements and use the periodic table to locate them

23. Use flame tests to identify chloride salts of sodium, potassium, calcium, strontium and barium

Results:

Element Colour

Sodium Chloride Orange

Potassium Chloride Lilac

Copper Chloride Blue

Calcium Chloride Red/Maroon

Iron (Ferric) Green


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Chloride

Lithium Chloride Red

24. Write the formulae of simple compounds

25. Identify whether a change is physical or chemical

-A physical change is when a substance changes by no new substance is formed

-Physical changes occur when the state of a substance changes or it is crushed, group or cut into

smaller pieces

-A chemical change or chemical reaction occurs whenever a new substance forms

-Sometimes, chemical changes are obvious while others are more difficult to observe


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26. Write simple word equations to describe a chemical change

-A chemical reaction can be represented by a word equation: reactants products

27. List the four types of chemical reactions as combination, decomposition, precipitation and

combustion

-Chemical reactions can be classified into combination reactions, decomposition reaction,

precipitation reactions and combustion reactions (Memory: PreComComDecom XD)

28. Describe the role of a catalyst

-Enzymes are special catalysts found in our bodies

-Catalysts do not combine with other atoms or molecules; they only speed up the reaction rate

29. Investigate how chemical reactions can be speeded up

-The rate of reaction can be affected by concentration of reactants, temperature, surface area and

catalysts

30. Draw a model of an atom using electron shells


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31. Trace atomic history

32. Use conventional notation for atomic number and mass number to describe atoms

-The atomic number is number ofprotons in the nucleus

-The mass number is the number ofprotons and neutrons in the nucleus

33. Appreciate the role of nanotechnology


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34. Explain what a microbe is

-Microbe is the shortened word for microorganisms

-Microbes are single-celled living organisms usually too small to be seen with a human eye

35. Classify microbes as fungi, bacteria, protists or viruses

-Microbes are classified into five groups: bacteria, fungi, protozoa, algae and viruses

36. Describe microbes by size

-Relationship Between Sizes of Various Objects and Microbes


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37. Identify the main parts of the microscope

38. Identify the types of microscopes used to observe different microbes

-Fungi can be seen with the human eye and observed under a light microscope

-Protozoa and bacteria are viewed with a light microscope

-Viruses can only be viewed under an electron microscope

39. Describe some of the ways used to study microbes

-Microbiologists study microorganisms

-Microbiologists commonly use petri dishes to grow or culture microbes

-Very small units of measurement are used to measure microbes

40. Describe binary fission

-Binary fission is when a parent cell divides to become two identical daughter cells

41. Identify the use of antibiotics

-Antibiotics are chemicals or drugs that kill bacteria, usually by destroying their cell walls

42. Outline the conditions necessary for bacteria to grow

-Bacteria grow and produce rapidly only in moist and warm environments


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43. Outline how fungi reproduce

-Fungi are made up of thread-like structures called hyphae that grow into food and digest nutrients

-Fungi such as mushrooms and moulds have two ways of reproducing:

1. Hyphae breaks of and begins to grow

2.

Sporangium bursts open, releasing spores into the air

-Yeasts reproduce by budding:


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44. Compare viral and fungal reproduction

-A virus is only able to reproduce inside a host cell

-The virus hijacks the host cell, forcing it to produce new viruses until it bursts open and releases the

new viruses

-Fungi such as mushrooms and moulds have two ways of reproducing:

1. Hyphae breaks of and begins to grow

2. Sporangium bursts open, releasing spores into the air

-Yeasts reproduce by budding

45. Identify ways in which microbes can be useful or harmful

-Some bacteria can help keep you healthy while others can cause diseases

-Fungi are also responsible for fungal diseases e.g. thrush, tinea and ringworm

-Yeast is a useful fungus used in bread, wine and beer

-Viruses cause many harmful diseases e.g. influenza

-Viruses have also been discovered to be helpful in a recent medial breakthrough, where it was

injected into a brain to destroy cancerous cells

46. Compare the equations for aerobic and anaerobic respiration

-Aerobic Respiration: glucose + oxygen carbon dioxide + water + energy


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-Anaerobic Respiration: glucose alcohol + carbon dioxide + energy

47. Outline methods for growing cultures in agar

-Method:

1. Expose the culture to the agar e.g. by using a cotton bud

2. Place the lid on the agar and seal with sticky tape immediately

3. Record your name, culture tested and date around the edge of the underside of the plate

4. Incubate samples upside down at 35C

48. List safety precautions for such experiments

Examples:

-Wash hands thoroughly with antibacterial soap after each experiment

-When observing the cultures, do not open the agar

49. Draw the general shapes of different kinds of protists

50. Observe microbes found on everyday objects

-Many everyday objects are fomites

-Non-living objects are not germ free

51. Observe microbes present in pond water


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-(See above diagram)

51. Identify the foods required for good health

-The foods required for good health are water and food that contain fibre and nutrients

-The five main nutrients are carbohydrates, lipids, proteins, vitamins and minerals

52. List the main body systems

-The main body systems are digestive, circulatory, respiratory, excretory, skeletal, muscular,

nervous, reproductive, lymphatic and urinary.

53. Describe how cells obtain nutrients and get rid of wastes

-Nutrients are extracted from the food we eat through digestion and wastes are deposited through

excretion.

55. Outline what a balanced diet means

-A balanced diet is one that contains the correct proportion of different types of foodto provide us

with different nutrients

-Below are the CSIROs guidelines, dividing food into 6 different groups


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56. Conduct simple food tests for starch, glucose and fats.

-Starch: Add iodine to the food being tested. Food containing starch will turn dark blue.

-Glucose: Lower testape into glucose solution. The testape will change to a certain colour if the food

contains glucose.

-Fats: Rub fat into a brown paper bag. The bag will turn translucent if the food contains fat.

-Protein: Lower albustix paper into protein solution. The paper will change to a certain colour

(match with chart on label) if the food contains protein.

57. Determine the chemical PE of a peanut

-It takes 42 joules of energy to raise the temperature of 10mL of water by 1C

58. Research a digestive disorder

Disorder Cause Symptoms

Anorexia nervosa Emotional problems Young women starve

themselves.

Appendicitis Appendix becoming inflamed

(due to a blockage or ulcers)

Symptoms include severe

pain, nausea, vomiting, andloss of appetite.

Appendectomy is an

operation where the appendix

is removed.

Aspirin When taken with little or no

liquid.

May cause uncontrolled

bleeding from stomach wall.

Cancer of the colon Lack ofroughage. Cancer.

Cleft plate Cleft plate does not join up

before birth.

Leaves a gay (may extend to

lips i.e. hare lips)

Constipation Blockage/troubles with

muscles in the rectum.

Difficulty in excretion of

faeces.

Diarrhoea Unwanted bacteria (e.g.

contaminated water)

Rapid passage (often liquid)

from the colon.

Food poisoning Bacteria (poorly cooked or Vomiting, cramps, diarrhoea,


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stored food) fever and death

Gallstones Bile becomes too

concentrated in gall bladder,

cholesterol precipitate as

gallstones

Blockage of bile and stops

digestion of fats

Heartburn Certain foods, eating too

quickly, stomach sphincters

not working properly. Excess

acids rise into oesophagus.

Burning sensation, damage to

oesophagus

Liver disease Excess alcohol consumption,

hepatitis. Alcohol causes

build-up offat among liver

cells and cirrhosis (scar

tissues)

Liver failure

Vomiting Infections, extreme pain,

stress. Messages from

stomach wall sent to brain

trigger reverse peristalsis

(contractions).

Vomit (partly digested food,

bile, acid and enzymes)

Stomach Ulcers Wall of stomach becomes

damaged, caused by

bacterium Helicobacter

Sore, ulcer in stomach

59. List the components and functions of blood components.

-Red blood cells:

Made in bone marrow

No nucleus

Carries haemoglobin (attracts/carries oxygen, contains iron - red)

Blood containing oxygen/oxygenated blood is red

Blood without oxygen/deoxygenated blood is blue (dull red)

Lasts for 100 days

One drop contains 5 million cells


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-White blood cells:

Bigger than red blood cells

Have a nucleus

We have few; one drop contains 3000 cells

Destroys bacteria/viruses by surrounding or producing chemicals

-Platelets:

Broken up blood cells produced in bone marrow

No nucleus

Triggers formation offibrin strands (blood clotting)

-Plasma:

Clear, yellow liquid

Cells are suspended in plasma

90% water

10% dissolved food, waste products, body chemicals (hormones)

Plasma helps regulate temperature; transfers heat

60. Observe blood slides under a microscope


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61. Outline what happens in the heart

-The heart pumps blood (4.5L every minute -adults) around the body

-90-120 beats per minute (children) or 70 (adults

-Beats are triggered by nerve impulses

-Made up ofstrong, cardiac muscle

-The human heart is made up of two pumps; one sends blood to the lungs (gathers oxygen) the

other receives oxygen carrying blood and pumps to head/around body

-Both halves of the heart has two main chambers; atrium (blood enters) and ventricle (blood pumps

out)

-Walls are thicker in the ventricle than the atrium; blood pumps out at a high pressure


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62. Identify the main blood vessel types

-Arteries :

Carry blood away from the heart to organs and tissues

They have thick elastic walls to withstand pressure

If an artery is cut, high pressure may cause blood spurting and rapid blood loss

Pulses can be felt at pressure points where bloodpasses into arteries close to bones

Pressure points: neck, armpit, inside of elbow, wrist, ankle, groin, behind knee

-Capillaries:

Arteries divide and connect with smaller tubes

Are only one cell thick

Allow nutrients and oxygen to pass out into nearby cells

Waste products are passed back and carried away

Most numerous type of blood vessel


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Serves every tissue

-Veins:

Capillaries join onto these wider tubes

Blood returns to heart for more oxygen

Low pressure

Valves stop blood flowing the wrong way

63. Describe the causes and events of a heart attack and first aid required

-Coronary arteries (branched offaorta) supply the heart muscle with blood

-These can become narrow due to build-ups offat and cholesterol; reduces blood flow

-Angina is the insufficient supply of oxygen and glucose to the heart and can be triggered by

exertion or emotional stress

-If the heart muscle dies due to lack of blood, the person experiences a heart attack

-Severity depends of size of area affected and conditions of other arteries

-Risk of heart attack may be reduced by inflating a balloon in affected area, inserting a titanium

alloy sleeve (stent) to spread artery walls, destroying blockage with laser beam and taking a

section of vein from the leg and connecting it

66. Research the role of a dialysis machine

-We can live with one healthy kidney but cannot survive if both kidneys fail

-Dialysis the filtering of blood by a machine and must be performed regularly (3 times a week; 8

hours)

67. Identify structures in the human respiratory system


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-Air enters the respiratory system through the nose and mouth

-In the nose, it is filtered (nostril hairs, cilia, mucus), warmed and moistened

-Air then moves from the pharynx into the trachea (windpipe)

-The epiglottis (flap of tissue) and larynx (voice box) stops food from entering the trachea

-Coughing (caused by cilia lining the tubes) and sneezing are reflexes which further protect the

trachea

-The trachea branches into two main bronchi which also branch off

-Air enters clusters of sacs (alveoli) in the bronchioles where gas exchange takes place

-There are around 500 million alveoli in your lungs

-Each alveolus lies close to the wall of a capillary

-20% of total blood volume is in the lungs

68. Investigate gases in inhaled and exhaled air

-Oxygen moves across walls ofcapillaries into blood (carried by haemoglobin)

-Dissolved waste gas (carbon dioxide) comes out of the capillaries back into the alveoli to be


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breathed out

-Replacement of air is the result ofbreathing (physical process) and is different from respiration

-Your ribs move up/out when you breathe due to the action of the muscles in the chest (intercostals)

and diaphragm (sheet of muscular tissue; separates chest from abdomen)

-Larger space in lungs causes a pressure decrease causing air to rush out (chest returns to normal

size)


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70. Describe how objects can become charged

-Most objects are neutral; no charge

-Objects can become charged if they rub against other objects or materials


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-Electrons may jump from one surface to another if rubbed together

-An object with fewer electrons than protons is positively charged

-An object with fewer protons than electrons is negatively charged

71. Draw diagrams to show charged and neutral objects

72. Describe objects by contact, friction and induction

-Static electricity is a collection of charges that remain stationary for some time, eventually

dissipating into air

-A neutral object can be attracted to a charged object because of induced charges

73. State the law of charges

-Opposite charges (negative & positive) attract

-Similar charges (positive & positive, negative & negative) repel

74. Use an electroscope to check for the presence of charge

-Electroscopes detect charge by the motion of a test object (below: foil ball)


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75. Draw electric field lines around charges

-Just as a planet has gravitation field, charges are surrounded by electric fields

-Larger charges have stronger electric fields

-The further away you go, the weaker the field becomes

76. Construct and draw simple electric circuits


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-The four basic parts of a simple circuit are an energy source, a conductor (wires), something to use

up the electricity and a switch

77. Design and draw a circuit containing a number of components


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78. Describe voltage, current and resistance using analogies

-Voltage is the amount of energy available to push charges around in a circuit

-The unit of measure is a volt (V)

-Voltage is measured using a voltmeter

-Analogy: voltage is like pressure from the pump that pushes the water through the pipes

-An electric current is moving electric charges

-Current is measured in ampere (A or amp)

-Current is measured with an ammeter

-Electrons move in an opposite direction to conventional current

-Analogy: The flow of current is similar to the flow of water however while water will flow out of a

cut pipe electric current will not usually flow out of a cut wire

-A resistance is something that restricts the flow of charge and takes moving charges of energy


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-It converts electrical energy into heat and light energy

79. Test various materials to distinguish between conductors and insulators

-A conductor is a substance that allows current to flow through easily (e.g. copper wire)

-An insulator is a material that does not normallyallow current to pass through (e.g. rubber, plastic)

-Rubber will conduct electricity if an extreme voltage is connected to it

80. Distinguish between DC and AC

-Direct current (DC) is where current flows in one direction

-Alternating current (AC) is where currents is pulled back and forth many times every second

-Electricity is supplied as AC (power stations) because it is easier to generate

81. Construct a wet cell

-A wet cell consists of two different metal plates placed in acid

-The acid dissolves one plate, releasing electrons to be joined onto the other plate creating energy

82. Construct series and parallel circuits

-In series circuits globes are arranged one after another in line with the battery

-In parallel circuits globes are arranged in separate branches between the same points


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83. Identify where series and parallel circuits are commonly used

-Series and parallel circuits are both used in Christmas-tree lights

-In a household, electricity wiring is one big parallel circuit

84. Connect an ammeter and voltmeter correctly in a circuit

-The red or positive ammeter terminal connects to the side of the circuit closest to the positive of

the cell or battery.

-The red or positive voltmeter terminal connects to the side of the circuit closest to the positive of

the cell or battery.

85. Identify where energy in a circuit comes from and where it is used

-Energy in a circuit comes from a voltage source e.g. a battery

-It is used up by a device such as a globe or motor

87. Describe the functions of safety devices in the home: RCD, fuse, circuit breaker

-A residual current detector (RCD) reduces the risk of electric shock by switching off the main power

switch if a difference is detected between the current entering and exiting the household


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-A fuse is a device (metal wire or strip) which melts when there is too much current to interrupt a

circuit in order to prevent damage or injury

-A circuit breaker is a switch which automatically disrupts a circuit when a fault is detecting to

protect from short circuit or overload damage

88. Discuss the dangers of an electric shock

-An electric shock can damage tissues and interfere with electrical signals driving the heart

-It can end up in electrocution; death by electricity

89. Evaluate the use of solar cells as an energy source for the future

-Burning coal, oil or gas to make electricity has harmful effects on the environment

-Solar cells take the energy in sunlight and convert it into electrical energy

-Research is being conducted in order to provide a reliable source of electricity, provide solar energy

to remote communities, replace noisy generator, provide portable power sources and provide a

renewable and sustainable source of energy

-Solar (photovoltaic) cells are made of semi-conductors (e.g. silicon) that do not conduct as well as

metals

-Small amounts of boron is added to one layer and phosphorus to the other to allow them to

conduct better

-Light hitting the join between layers knocks electrons off atoms which flow out of the top metal

conductor and around the circuit

-This energy is used to power appliances; make electricity

90. Explain observations of demonstrations with the van de Graaf generator


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-A Van de Graaf generator produces a large build-up of charge on its metal dome

-It can be used to demonstrate static electricity effects

91. Describe an ecosystem in terms of organisms

-An ecosystem refers to the living organisms inhabiting a specific region, their interaction and effects

on them of the non-living environment around them

-Ecology is the study of an ecosystem

-Living organism includes all of the plants and animals that live/visit the region; community

93. Describe the main factors that affect Australias ecosystems

-The main factors that affect Australias ecosystems are flood, bushfire and drought

92. List 3 types of ecosystems

94. Identify the factors that affect the size of populations of organism

-Population is the number of the organism that is present

95. Describe some adaptations of living things to factors in their environment


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-Adaptations are behavioural and physical characteristics that allow an organism to survive in a

specific environment

-A physical adaptation is one the organism is born with and has no control over

-Behavioural adaptations can be instinctive or learnt

96. Give examples of physical (structural) and behavioural adaptations

-An example of a physical adaptation is the spine (thick, coarse fur) of an echidna providing

protection from predators

-An example of an instinctive behavioural adaption is an animal seeking shade on a hot day

-An example of a learnt behavioural adaptation is an animal learning to hunt for food

97. Distinguish between biotic and abiotic features in the environment

-Living (biotic) factors include all other plants and animals contacting directly or influencing indirectly

-Competition; animals living in the same area share the same requirements and will compete for

them

-Dispersal; how an organism is scatter, animals move freely while plants rely on wind

-Predation; one animal catching and eating another

-Human intervention; most power and influential

-Non-living (abiotic) environment include physical factors e.g. rainfall, temperature, wind, sunlight,

rocks, soil and water

-Temperature; biological processes e.g. digestion, respiration, excretion and reproduction take place

at an optimum temperature

-Humidity; in humid areas plants/animals lose very little water, deserts have low humidity

-Light:

provides green plants with energy for photosynthesis,

reflected at the surface in water

the photic zone is where light penetrates (green/blue), seaweed/kelp grow here

-Soil/water acidity; plants and water organisms have preferred soil acidity, measured with pH scale


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-Salinity; saltiness of water, saltwater and marine organisms experience different salinity thus body

functions vary

-Mineral salts; nutrients in the soil

-Wave and water currents:

Intertidal area lies between high and low tides

Exposed to air at low tide, submerged at high tide

-Organisms living here

-Shelter; protection from predators and weather; different animals/plants require different types of

shelters

-Wind and air currents; only plants with strong root systems can survive in areas with high wind

98. Write the equation for photosynthesis and respiration

-The equation for photosynthesis is: carbon dioxide + water glucose + oxygen (sunlight)

-The equation for respiration is glucose + oxygen carbon dioxide + water + energy

-The equations for respiration and photosynthesis are the reverse of each other

99. Describe the roles of photosynthesis and respiration in ecosystems

-Photosynthesis is required by green plants to convert the light from the Sun into energy they need

-Respiration is required by other organisms (consumers) in order to convert the food they eat intoenergy they need

100. Construct simple food chains

-The interaction between producers, primary consumers, secondary consumers and tertiary

consumers form a sequence referred to as a food chain

-An arrow means is eaten by


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101. Construct simple food webs

-The interaction of food chains is known as a food web

102. Outline the need for biodiversity


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-Biodiversity is the number of different species present in a community

-Communities with high biodiversity survive environmental changes better as there are multiple

sources of food and alternatives if one is destroyed; they are more stable

103. Describe the role of decomposers in the food chain

-All organic matter contains carbon

-Decomposers recycle organic matter in dead bodies of plants/animals and releases the nutrients

they contain

104. Use examples to explain the relationship: mutualism and competition

-Mutualism (symbiosis) is where both organisms benefit by the relationship

-For example, slime on a false clown anemone fish prevents it being stung while it lives and feeds

under the anemones protection, the anemone receives scraps of food and is clean of parasites

-Competition is where different animals/plants fight for the same food source, water or nesting

material

105. Describe how humans have affected the environment

-Humans have affected the environment by polluting the atmosphere, land and water

106. Identify the causes of air pollution, enhanced global warming, water pollution and soilpollution

-Air pollution is caused by industrial activity releasing sulphur dioxide, nitrogen dioxide, carbon

monoxide, carbon dioxide, hydrogen sulphide, dust and smoke

-Motor vehicles release hydrocarbons, lead, nitric oxide and carbon monoxide

-Enhanced global warming is caused by the enhanced greenhouse effect and leads to global warming

-The main greenhouse gasses are carbon dioxide, methane, nitrous oxide, ozone and water vapour

-Water pollution is caused by sewage (soap, detergents, cleaning agents, human wastes),

agricultural run-off (nitrogen, phosphorus), sediment pollution (soil), salinisation (surface salts) and

inorganic chemicals (acid rain)

-Soil pollution (soil degradation) is caused by overgrazing and deforestation

-Trees take water from the ground and releases it back into the atmosphere through transpiration

107. Analyse the impact of air pollution, enhanced global warming, water pollution and soil

pollution on the environment


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-In the presence of sunlight air pollutants react to form ozone and nitric gas and organic compounds

such as formaldehyde; smog

-Global warming will increase both temperature and sea levels; increased floods and possible

destruction of farmland and island nations

-Removal of plant life makes soil vulnerable to wind and rain; erosion

-Desertification can result from deforestation

108. Justify the need for conservation

-Conservation is keeping a habitat undisturbed and free of human interaction in order to preserve

the life within it

-Both long-term and short-term conservation actions exist

-Humans rely on the living organism around them for oxygen, food and pharmaceutical drugs

Year 8 Yearly Science Notes-Tang's USB

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