This page contains the AQA GCSE Biology B18 Biodiversity and Ecosystem  kerboodle answers for revision and understanding .This page also contains the link to the notes and video for the revision of this topic.

Banner 1

B 18.1 The Human Population ExplosionAQA GCSE Biology B18 Biodiversity and Ecosystem Kerboodle Answers: Page No. 287

1a The human population has increased so rapidly over the past couple of hundred years because we have discovered how to grow more food than we could ever gather from the wild. We can cure or prevent many killer diseases. We have no natural predators. This helps to explain why the human population has grown so fast.

b People reduce the amount of land available for other animals and plants as more and more land is used for building houses, shops, industrial sites, and roads on. This destroys the habitats of other living organisms and reduces biodiversity.

• We use billions of acres of land around the world for farming. Wherever people farm, the natural animal and plant populations are destroyed.

• We dig up vast areas of land for quarries to obtain rocks and metal ores, reducing the land available for other organisms.

• The waste produced by humans pollutes the environment and processing it takes up land, affecting biodiversity.

2 Resources that humans are using up are

1 Land.

2 Metal ores.

3 Fossil fuels, wood.

b The standard of living has improved over the past 100 years as

• Use of electricity for lighting/heating/entertainment.

 • Increased food production.

 • Improved medicines.

 • Use of fossil fuels for transport.

 • Development of plastics • improved waste disposal • improved sanitation.

3 Different ways that the ever-increasing human population is causing pollution :

Points may include:

  • Increased waste – including bodily waste, industrial waste, packaging, uneaten food, and disposable goods.

 • Exhaust gases from transport.

 • Use of pesticides and fertilisers in farming.

Banner 2

B18.2 Land and water pollutionAQA GCSE Biology B18 Biodiversity and Ecosystem Kerboodle Answers: Page No. 289

1 Human bodily waste and waste water is called seways.

b It important to dispose of sewage carefully because toxic chemicals can spread from waste into soil, toxic chemicals can be washed into waterways,  sewage can pollute soil with dangerous chemicals and gut parasites,  toxins build up in organisms along food chain (bioaccumulation),  largest predators die or are infertile due to toxic chemical build‑up.

c Bioindicators are used to monitor pollution level in waterways.

2 a Farming can cause pollution of the land. The polluting effects farming can have on are

i land

Polluting effects are:

 • Pesticides and herbicides spread from crops into soil.

• Plant material contaminated with toxins.

• Small levels of toxins taken in by animals eating affected plant material.

• Toxins build up along food chains (bioaccumulation) until toxic levels are reached in top predators.

ii water

Polluting effects are:

• Fertilisers washed from the soil into streams, ponds, and rivers. 

• Nitrates in fertilisers encourage the rapid growth of algae and water plants.

 • Microorganisms feeding on the plants use up oxygen decreasing the levels of oxygen.

• Other oxygen-dependent organisms then die because of a lack of oxygen.

b In the UK, a chemical called DDT was used up until the 1980s to kill insects. Large birds of prey and herons began to die and their bodies were found to have very high levels of DDT in them. It took a long time for any link to be made because: 

• DDT in pesticide contaminated soil and waterways.

• Organisms contaminated with toxins. 

• DDT builds up in organisms along food chain. 

• DDT levels become dangerously high in top predators (birds of prey, herons). 

• Effects of DDT not noticeable until dangerous levels reached. 

• Route through food chain not obvious.

Banner 3

B18.3 Air pollutionAQA GCSE Biology B18 Biodiversity and Ecosystem Kerboodle Answers: Page No. 291

1 Acidic gases from cars and factories burning fossil fuels can pollute:

a air

 Acidic gases released into atmosphere and spread around by wind in this way pollute air.

b water

Sulfur dioxide and nitrogen oxides dissolve into rain and snow, contaminating lakes/rivers/streams.

c land

Dilute sulfuric acid and nitric acid fall as acid rain and soak into soil.

2 a Flow chart to show how acid rain is produced:

Flow chart should include: Cars/power stations burn fossil fuels → acidic gases (e.g., sulfur dioxide, nitrogen oxides) formed → gases carried in the winds in atmosphere → sulfur acidic gases dissolve in rainwater and react with oxygen to form dilute sulfuric acid and nitric acid → acid rain falls.

b Some countries that have strict controls on sulfur emissions still suffer acid rain damage to their buildings and ecosystems as sulfur dioxide and nitrogen oxides can be carried high in air by winds.  Acidic gases can be blown from a country that does not control its sulfur emissions to a country  that has strict emission controls and fall as acid rain.

3 a The percentage reduction in sulfur dioxide emissions in the EU between 1990 and 2010:

25000 − 5000 = 20000,  

× 100 = 80, reduction of 80%.

b Reasons for the observed reductions are

• More efficient catalytic converters in cars. 

• Cleaner fuels. 

• Legislation to control emissions from factories.

c Observations to affect the levels of acid rain in Europe:

Levels of acid rain should fall as sulfur dioxide emissions fall, unless prevailing winds carry acidic gases from non-European countries.

4 a The change in sulfur dioxide emissions for:

 i China, between 1850and 1975  

1850: 0 million tones.

1975: 4 million tones.

 4 million tone increase.

ii the USA, between 1975 and 2000

1975: 14 million tones.

2000: 8 million tones.

 6 million tone decrease.

b The implications for global biodiversity of the trends seen in Figure 2b as figure 2b shows increasing global sulfur dioxide emissions, causing increasing acid rain.  Acid rain directly damages plant life by falling on plants and by soaking into soil and being taken up by roots.  Acid rain contaminates soil and watercourses, making them more acidic and eventually unable to sustain life.  Increasing sulfur dioxide levels threaten to reduce global biodiversity as whole ecosystems can be destroyed.

Banner 4

B 18.4 Deforestation and peat destructionAQA GCSE Biology B18 Biodiversity and Ecosystem Kerboodle Answers: Page No. 293

1 deforestation is defined as removal of large areas of forest by felling/burning without trees being replaced. 

b Deforestation affects biodiversity as tropical rainforests contain more biodiversity than any other land environment.  Loss of forests means biodiversity of plant and animal life is also lost  as habitats are destroyed and species become extinct.  Many species are being destroyed before being identified and studied, so potential new sources of medicine or food could be lost.

2 Deforestation increases the amount of carbon dioxide in the atmosphere as :

Carbon dioxide produced by burning of trees. 

Carbon dioxide produced by decomposition of dead vegetation.

Less carbon dioxide removed from atmosphere by growing plants.

3 a The numbers of peat bogs and peat lands in the world are decreasing because use of peat as fuel and by gardeners as compost.

B This is cause for concern because CO₂ is released into atmosphere as peat is burnt or used as compost,  increasing atmospheric levels of carbon dioxide  and depleting the carbon store. 

Destruction of peat bogs destroys habitats and reduces biodiversity.

4 The conflict between the need for cheap available compost and the need to conserve peat bogs and peatlands are

• Cheap compost needed by gardeners and horticulturists to improve soil properties, promote seed germination, and increase food production, alternative, ‘peat‑free’ composts are available but are less popular. 

• Peat bogs and peat lands vital to biodiversity as they form habitat for many organisms adapted to live in acidic conditions. 

• Peat forms very slowly and under very specific conditions – cannot be replaced as quickly as it is being used.

Banner 5

B 18.5 Global warming AQA GCSE Biology B18 Biodiversity and Ecosystem Kerboodle Answers: Page No. 295

1 The data in Figure 1 to produce a bar chart showing the maximum recorded level of carbon dioxide In the atmosphere every tenth year from 1960 to 2010 as Correct y-axis label and scale, Correct x-axis label and scale, data plotted correctly.

b Trend you can see on your chart :

Carbon dioxide levels rising steadily over time,  partly as a result of human activities.

c The greenhouse effect is energy transferred from Sun to Earth. 

Much of this heat is reflected back into space but some is absorbed by greenhouse gases in the atmosphere and reradiated back to Earth. Earth’s surface and atmosphere are warmed (greenhouse effect), maintaining conditions ideal for life

2 a Global warming is occurring because atmospheric levels of greenhouse gases increasing  as a result of human activity, increasing greenhouse effect and causing global temperatures to rise.

b The biological consequences of global warming are

• Loss of habitat – reducing biodiversity.

• Changes in distribution – some organisms may disappear from some areas as habitat changes.

3 An organism that has been, or might be, affected by global warming. The effect of global warming on the survival of this organism is that the effects of global warming are the environmental and social changes caused (directly or indirectly) by human emissions of greenhouse gases. There is a scientific consensus that climate change is occurring, and that human activities are the primary driver. Many impacts of climate change have already been observed, including glacier retreat, changes in the timing of seasonal events (e.g., earlier flowering of plants), and changes in agricultural productivity. Anthropogenic forcing has likely contributed to some of the observed changes, including sea level rise, changes in climate extremes, declines in Arctic sea ice extent and glacier retreat.

Baneer 6

B18.6 The impact of changeAQA GCSE Biology B18 Biodiversity and Ecosystem Kerboodle Answers: Page No. 297

1 a i seasonal environmental change: Natural changes  in environmental factors such as temperature, rainfall level, water availability, dissolved gases in water, and daylight hours  between different seasons  in temperate parts of the world.

ij geographical environmental change

Natural changes  in environmental factors such as soil structure or pH, altitude, water salinity, and water availability  between different geographical areas of the world.

b Organisms adapt to environmental changes are natural mutations cause features that enable some individuals within a population to cope better with a change to their environment.  These individuals are more likely to survive and breed (natural selection), passing on the beneficial feature to offspring.

2 a Number of breeding pairs of Dartford warblers in UK increasing.

b Reasons for the changes in the numbers of breeding pairs of Dartford warblers in 1963 and in 2010 : Dartford warblers cannot survive very cold winters. Number of breeding pairs dropped sharply in 1963,  suggesting cold winter that reduced population.  Number increased sharply in 2010, perhaps as a result of temperature increase.

C Aspect of climate change seems to be most closely linked to a change in the distribution of British birds : As temperature changes:

Changes in number of Dartford warblers indicate that numbers have increased as UK temperatures have increased but drop sharply after cold winters.  Drop in number of Dartford warblers in Spain indicates that too high a temperature also affects distribution.  Evidence suggests that change in mean UK temperature  and seasonal extremes of temperature  affect distribution of UK birds both within the country and between countries.

Banner 7

B18.7 Maintaining biodiversityAQA GCSE Biology B18 Biodiversity and Ecosystem Kerboodle Answers: Page No. 299

1 a It is important to maintain biodiversity because it is important for environmental health, offers potential source of new food crops, offers potential source of new medicines.  

b Breeding programs for endangered species – restoring endangered species to sustainable populations,  protection and regeneration of rare habitats – protecting different animals and plants, reintroduction of field margins and hedgerows – allowing biodiversity to be maintained in agricultural land,  reduction of deforestation – maintaining habitats,  recycling resources – reducing habitat loss and pollution.

c There is a conflict between maintaining biodiversity and human needs as

• Increased field margins limiting land available for food production,

• Reduction of deforestation limiting land available for food production, 

• Taxes on landfill waste increasing costs to businesses.

2 Using the data in Figure 3a

a Levels have fallen steadily.

b This data demonstrates the effect of governments on carbon emissions as this data suggests that Kyoto agreement drove UK government to take action to limit carbon dioxide emissions and that government intervention via legislation  has been successfully.

c A fall in carbon dioxide emissions globally might help maintain biodiversity as

  • Reduce or prevent increase in greenhouse effect and global warming – maintaining biodiversity by preserving Arctic and Antarctic ice habitat.

 • Preventing rises in sea levels that will destroy biodiverse mangrove forests.

3 Taxes can be used to help reduce human damage to ecosystems and biodiversity as data shows that as landfill tax increased, amount of material going into landfill fell. Taxes on waste and emissions  can be used as an effective incentive to change human habits  and promote research into less damaging alternatives (e.g., recycling rather than landfill). 

Banner 8

This page contains the detailed and easy notes for AQA GCSE Biology Ecology for revision and understanding Ecology.

Banner 1

New (9-1) AQA GCSE Biology Paper 2: Complete Revision Summary

ECOLOGY

Banner 2

4.7 Ecology  

• Communities
• Abiotic Factor
• Biotic Factor
• Adaptations
• Carbon Cycle
• Waste Cycle
• Climate Change
• Biodiversity
• Waste Management
• Land Use
• Deforestation
• Global Warming
• Food Chain
• Pyramids
• Food Production

• Organism – Individual Species

• Population – Groups of similar organisms living in the same area.

• Community – Groups of population living in a defined area

Banner 3

• Ecosystem – Groups of communities with its living and non-living factors

• Biosphere – Groups of different Ecosystem

• Organisms, Populations, and Communities: In a forest, each pine tree is an organism. Together, all the pine trees make up a population. All the plant and animal species in the forest comprise a community.

• Ecosystems: This coastal ecosystem in the southeastern United States includes living organisms and the environment in which they live.

• The Biosphere: Encompasses all the ecosystems on Earth.

Banner 4

ECOSYSTEM

It is a segment of nature consisting of a biological community and its physical environment both interacting and exchanging materials as well as energy. e.g – pond ecosystem.

Ecosystem is the group of communities interacting with the biotic and the abiotic factors.

  
Banner 3

ABIOTIC FACTORS

Non-living substances and factors of an ecosystem. E.g temperature, light, wind.

Most of the abiotic factors affects photosynthesis which affects the producers which inturn affect the complete food chain.

Light – Less light limits the photosynthesis and affect the entire food chain Plant in low light have broader leaves to increase surface area for absorption.

Water – Water is required for growth. Less water limits the photosynthesis and affect the entire food chain

pH – The low pH makes the soil acidic and limits the growth of plants and affect the entire food chain

Temperature – Temperature also limits the rate of photosynthesis which affects the food chain

Oxygen – The oxygen is required for the growth of the plant. In low levels of oxygen the organisms cannot survive

Carbon Dioxide – Carbon dioxide is required for growth. Less water limits the photosynthesis and affect the entire food chain.

Wind – Plants growing in high wind adapt different shapes. Wind also affects the rate of transpiration.

BIOTIC FACTORS

Constitute all the living members of an ecosystem. E.g Producers, Consumers, Decomposers.

FOOD – Food availability helps the species to grow and reproduce.

PATHOGEN – A pathogen can cause infectious disease d affect the growth of the population and can also wipe the whole population

PARASITES – Parasites can limit the growth of the host and affect the • population of the community.

COMPETITION – Increasing competition can affect the growth of the population and can outcome the individual of a population

PREDATORS – Increase in predation can decrease the population of the prey.

INTERDEPENDENCE

• One species is dependent on other. Like plants are dependent on insects for seed dispersal and pollination.
• Herbivores are dependent on plants for food.
• If one species is removed it affect the other species.

COMPETITION IN PLANTS AND ANIMALS

 
Banner 4

ADAPTATIONS

Special Features that give the organisms the survival advantage and helps the organism to survive in the extreme conditions.

PLANT REQUIRMENTS

• Water, space, minerals, carbon dioxide for photosynthesis
• Oxygen for respiration.
• Major adaptations they have make them successful in getting these components from the environment

ANIMAL REQUIREMENTS

• Food to survive
• Oxygen for respiration
• Mate to reproduce.

Adaptations can be structural, behavioural and functional adaptations.

PLANT ADAPTIONS

 ANIMAL ADAPTATIONS

                                                            EXTREMOPHILES

 STUDYING COMMUNITIES

Quadrat Method – Random squares are placed at different point and the species within that squares are counted.

Transect Method – A line is placed and the species that are within this line or few cm above or below this line are counted and recorded.

Sample Size – The sample to be take for observation.

Mean – It is the statistical value calculate by adding all the values divided by total number of values.

Median – It is the middle value of the data.

Mode – The value that has the greatest frequency.

Range: It is the highest value take away the lowest value.

TROPHIC LEVELS

Producers: They produce their own food as they can photosynthesize and converts Sun’s energy to chemical energy.

Primary Consumers – They are herbivores which feeds on plants.

Secondary Consumers – They are carnivores or omnivores which feeds on herbivores.

Tertiary Consumers – They are at the top of food chain

Decomposers – Feed on dead and decay matter.

Baneer 6

FOOD CHAINS

• It is the relationship of who eats whom.
• At each level there is a loss of energy and only 10% is transferred to the next trophic level so the food chains are mostly restricted to 3-4 tropic levels.
• Sun is the principal source of energy driving the whole food chain.

PREDATOR- PREY RELATIONSHIP

• Prey increases

• Predator increases

• Prey Decreases

• Predator decreases

PYRAMIDS OF BIOMASS

• Graphical representation of the mass of the living organism at each level.
• It is upright as :-
• Not all the biomass is eaten by the next trophic level
• Some of the biomass is lost as energy at each trophic level.
• Some of the biomass is lost as waste product at the trophic level.

Biomass is the mass of the materials contained in the living organisms.

PYRAMIDS OF NUMBERS

• It is the graphical representation of the number of organisms at each trophic level.
• It can be upright, inverted or upside down.

ENERGY TRANSFER PYRAMID

• It is the graphical representation of energy at each trophic level.
• Energy Lost at Each trophic Levels

1. a) Energy is required for movement, growth and repair
2. b) Energy is lost in digestion
3. c) Energy is lost in maintaining constant body temperature
4. d) Energy is lost as heat during respiration.

CYCLING OF MATERIALS

• Decomposers play an important role in material recycling
• Decomposers feeds on dead and decay matter. They break the organic matter into simple components and return them to soil.
• The products carbon dioxide into the atmosphere by the process of decomposition.
• Bacteria and Fungi

Proteins in the dead and decay matter is converted into nitrates and returned to soil.

Banner 7

WATER CYCLE

Evaporation – water is evaporated from the water bodies like sea, lakes etc and form water vapours.

Transpiration – The water vapours are also lost from the surface of the plants.

Respiration – Respiration produced water vapour and it is lost in the form of water vapours

Condensation – The water vapour from all the above source cools and condense to form clouds.

Precipitation – When clouds get full the fall of as rain and the cycle continues.

CARBON CYCLE

Photosynthesis – It is the process by which green plants take in carbon dioxide from the

Respiration – The carbon dioxide is returned back to the atmosphere

Combustion – The fuel burns releasing carbon dioxide into the atmosphere

Decomposition – It is the process by which decomposer decay dead material and release carbon dioxide into the atmosphere

Fosslization – Dead Plants and Animals form fossil fuels which burns to release carbon dioxide into the atmosphere

Banner 8

DECOMPOSITION

They are the microorganisms that breaks the dead and decay materials into simpler components. They are very important as they return the nutrients and minerals back into the atmosphere

Condition required for decay

1. a) Oxygen
2. b) Warm Conditions
3. c) Moist Conditions

Decay process forms methane which can be used as fuel.

Decay process also produce compost which can be used as a manure.

Plants

Animals

DECOMPOSERS

Breaks the dead and decaying plants and animals into simple components which are recycled in the atmosphere.

BIODIVERSITY

It is the measure of number of difference species in an area. Greater the biodiversity more stable is the ecosystem and less dependency on other organisms.

Uses of Biodiversity

• It is required to make the ecological balance as one species is dependent on the other.
• It is required for medicine like medicinal plants.
• It is required for agriculture and poultry.
• It is required to maintain ecotourism.
• Species are dependent on one another. So if one species is affected it can affect the entire population.

Threats to Biodiversity: All factors are interconnected

• Deforestation : Rapid population growth causing clearing of forests and making industries and home causing climate change and global warming_
• Population Growth – Leading to deforestation, monoculture
• Agriculture – Increasing food demand is causing monoculture causing reduction in gene pool.
• Industrialization – Due to increasing population size

AIR POLLUTION

ACID RAIN

Formation

Sulphur and nitrogen present in fossil fuels forms carbon dioxide and sulphur dioxide by combustion.

Carbon dioxide and sulphur dioxide combine with rainwater forming nitric acid and sulphuric acid and falls as acid rain.

Effects

1. a) Makes soil acidic
2. b) Damage trees and aquatic life
3. c) Corrossion of building
4. d) Errodes building and rocks

Prevention

1. a) Decrease in use of fossil fuels.
2. b) Treat the waste to remove nitrogen and sulphur before evolving.
3. c) Use alternative source of energy.

Banner 9

 SMOG

Smog is opaque or dark fog having condensed water vapours, dust, smoke and gases.

• Mixture of nitrogen dioxide and sulphur dioxide particulates in the lower atmosphere.
• Depletes ozones layer, cause dimming effect.
• Lowers the Earth’s temperature
• If inhaled causes damage to lungs, respiratory problems and cardiovascular diseases.

WATER POLLUTION

• Fertilizers washed away
• Increases the nutrient content of water causing algal bloom

ALGAL BLOOM

• Forms green layer, block sunlight
• Death of plants, decreasing oxygen in water. Death of other species.
• Decomposers increasing further decreasing oxygen.

Banner 10

BIOMAGNIFICATION

It is increase in the concentration of a persistent chemical with the rise in trophic level. As the toxic products go along the food chain the concentration of the toxic chemicals increases.

LAND POLLUTION

• Solid Waste
• Plastic, metals and other man made chemicals fills the landfill sites
• Chemicals -Toxic Chemicals come from industries and agricultures sites.
• Agriculture Waste – Spray of insecticides, pesticides and weedicide contributes to land pollution.

DEFORESTATION

Causes

• Rapid industrialization, population growth and urbanization
• Clearing of forests form making home and industries. Increase in agriculture to grow food and fuel crops.

Effects

1. a) Increase in carbon dioxide levels causing global warming and climate change.
2. b) Loss of biodiversity by causing habitat destruction
3. c) Causing extinction of species.

PEAT BOG DESTRUCTION

What is Peat ?

• It is a plant material that is not decayed due to acidic conditions.
• Forms peatlands and peat bogs and are massive storehouse of carbon and host many organisms.

Uses of Peat

1. a) Unique carbon store
2. b) Habitat for many microorganism, plants and animals that can survive in acidic conditions.
3. c) Used as fuel

Effect of Peat Bog Reduction

• Causes loss of biodiversity.
• Takes millions of years to form.

GREENHOUSE EFFECT

It is warming effect found in green house by allowing solar radiations to pass in but preventing long wave heat radiations to pass out due to glass panes, water vapours and carbon dioxide.

GLOBAL WARMING

Rise in mean temperature of the earth. It is due to the excess amount of green house gases present in the atmosphere

• Climate Change
• Habitat Loss
• Floods
• Change in Migration of Birds
• Change in distribution of plants and animals
• Change in seasonal pattern
• Loss of Biodiversity causing extinction of species.

MAINTAINING BIODIVERSITY

In situ Conservation

• It is the protection of endangered species in their own natural habitat like making national parks, wildlife sanctuary and making biosphere reserves.
• Breeding programmes are also carried in these areas to increase the population of endangered species.

Ex Situ Conservation

• Preserving the biodiversity outside their natural habitat like
• Zoos, botanical garden, tissue culture, seed banks and gene bank.

Preventing Deforestation and Combustion

• Preventing deforestation and planting more trees can reduce the carbon emissions and can prevent global warming and climate change
• Recycling and using alternative sources of energy
• Recycling and using alternative sources of energy can reduce the dependency on fossil fuels causing reducing the carbon emissions preventing global warming, climate change and its effects.

Banner 11

FOOD SECURITY

What is Food Security ?

Growing sufficient healthy food to feed the population and accessibility of the population to grow or buy the healthy food.

Factors Affecting Food Security

1. a) Population Growth
2. b) Inclination toward unhealthy and easy to cook foods
3. c) Spread of Disease
4. d) Pest and Insect attack to the crop.
5. e) Climate Change
6. f) Acid Rain and Pollution
7. g) Water Pollution
8. h) Increase in cost of agricultural supplies
9. i) Food versus Fuel Issue

EFFICIENT FOOD PRODUCTION

• Increasing more plant based products
• When plant based products are used they have the highest biomass and maximum energy as they are at the initial level of food chain.
• Plant based product reduces the dependency on animal products.
• Reducing the level of food chain
• At each trophic level, there is energy loss.
• So if the food chain levels are reduced maximum energy and biomass can be obtained.

Intensive Farming

In intensive farming the animals are grown to limit energy loss and produce maximum biomass by

1. a) Restricting Movement – By restricting movement energy loss in movement is prevented.
2. b) Rearing them at constant temperature – Energy loss in maintaining body temperature is prevented.
3. c) Giving them easy to digest food – It reduced energy loss in digestion.
4. d) Giving them protein rich diet – It helps to grow more biomass

SUSTAINABLE FOOD PRODUCTION

1. a) Use of genetic engineering to increase the yield of the crops and making more disease resistant and high yield variety.
2. b) Use of microorganisms for food production

Mycoprotein are the proteins source from fungi. It is excellent food source and is sustainable grown in fermenter.

Banner 11

KEY TERMS

1. a) Communities – It is an assemblage of populations of different species of plants, animals, bacteria and fungi which live in a particular area and interact with one another through competition, predation, mutualism, etc.
2. b) Ecosystem – It is a segment of nature consisting of a biological community and its physical environment both interacting and exchanging materials as well as energy. e.g – pond ecosystem
3. c) Interdependence – refers to a situation in which both species require the action of the other to function.
4. d) Stable Communities – A stable communities are those is in which the size of populations of all species remains comparatively constant over time.
5. e) Abiotic Factor – Non-living substances and factors of an ecosystem. E.g temperature, light, wind.
6. f) Biotic Factor – Constitute all the living members of an ecosystem. E.g Producers, Consumers, Decomposers.
7. g) Predator – It captures, kill and on another organisms called prey. Ex -tiger
8. h) Prey – an animal hunted or seized to eat, especially from a carnivorous animal
9. i) Pathogen – a bacterium, virus or other micro-organism that can cause disease.
10. j) Parasite – it feeds on another organism called host. The parasite spends a part or whole of its life on or in the body of the host.
11. k) Competition – it is a rivalry between two or more organisms for obtaining the same resources.
12. l) Abundance – The number of organisms in a population, combining intensity and prevalence.
13. m) Distribution – spatial relationship between individuals in a population.
14. n) Quadrat – A quadrant is a sampling unit used for the quantitative study of the plant community. Can be rectangular or circular. Used to measure the coverage and abundance of plants or animals
15. o) Sample Size – The sample to be take for observation.
16. p) Mean – It is the statistical value calculate by adding all the values divided by total number of values.
17. q) Range: It is the highest value take away the lowest value.
18. s) Median – It is the middle value of the data.
19. t) Mode – The value that has the greatest frequency.
20. u) Transect – A transect is a long rectangular sample. It is used to study variation in vegetation.
21. v) Adaptation – Changes in the form or behavior of an organism during its life as a response to environmental stimuli.
22. w) Biomass – mass of the individuals per unit area
23. x) Producers – They are Photosynthetic or autotrophic plants which are able to synthesize organic food from inorganic raw materials with the help of solar radiations.
24. a) Precipitation – Precipitation includes rain, snow, and hail.
25. b) Condensation – gas changing to a liquid.
26. c) Evaporation – liquid’s surface changing to a gas.
27. d) Transpiration – water vapor being released from plants and soil.
28. g) Combustion – It occurs when any organic material is reacted (burned) in the presence of oxygen to give off the products of carbon dioxide and water and Energy
29. h) Decomposition – It is the process of breaking down of a substance/waste biomass into its constituent parts by decomposers(bacteria, fungi)
30. j) Biodiversity – It refers to all aspects of variety in the living world.
31. k) Acid Rain – It is rainfall and other forms of precipitation with a pH of less than 5.
32. l) Smog – Smog is opaque or dark fog having condensed water vapours, dust, smoke and gases.
33. m) Eutrophication – It is excessive growth of algae, plants and animals in water bodies due to the nutrient enrichment particularly with nitrogen and phosphorous.
34. n) Biomagnification – It is increase in the concentration of a persistent chemical with the rise in trophic level. Eg organochlorine like DDT
35. o) Global Warming – Rise in mean temperature of the earth. It is due to the excess amount of green house gases present in the atmosphere
36. p) Greenhouse Effect – It is warming effect found in green house by allowing solar radiations to pass in but preventing long wave heat radiations to pass out due to glass panes, water vapours and carbon dioxide.
37. q) Trophic Level – Trophic level is a step or division of food chain which is characterized by the method of obtaining its food.
38. r) Pyramids of Biomass – graphic representation of biomass present sequence-wise per unit area of different trophic levels with producers at the base and top carnivore kept at the tip.
39. s) Pyramids of Number – graphic representation of number of individuals per unit area of various trophic levels step-wise with producers at the base and top carnivore kept at the tip.
40. t) Food Security – Growing sufficient healthy food to feed the population and accessibility of the population to grow or buy the healthy food. All people have access to sufficient, safe and nutritious food that meets their dietary preferences and dietary needs for an active and healthy life.
41. u) Fermenter – An organism that causes fermentation.
42. v) Biotechnology – living organisms are used to produce useful products and chemicals or to perform an industrial task. It is mainly used in agriculture, food science and medicine.

w) Mycoprotein – Mycoprotein is a type of unicellular protein derived from fungi. It is excellent food source and is sustainable grown in fermenter

Banner 12

Disclaimer:

I have tried my level best to cover the maximum of your specification. But this is not the alternative to the textbook. You should cover the specification or the textbook thoroughly. This is the quick revision to help you cover the gist of everything. In case you spot any errors then do let us know and we will rectify it.

References:

BBC Bitesize

Wikipedia

Wikimedia Commons

Image Source:

Wikipedia

Wikimedia

Commons

Flickr

Pixabay

Make sure you have watched the above videos and are familiar with the key definations before trying these questions. It is also good to time yourself while doing these questions so that you can work on the speed as well.

• B18- Biodiversity and the Ecosystem

• Biodiversity & Effect of Humans on Ecosystems 1 MS
• Biodiversity & Effect of Humans on Ecosystems 1 QP
• Biodiversity & Effect of Humans on Ecosystems 2 MS
• Biodiversity & Effect of Humans on Ecosystems 2 QP
• Biodiversity & Effect of Humans on Ecosystems 3 MS
• Biodiversity & Effect of Humans on Ecosystems 3 QP
• Food Production 1 MS
• Food Production 1 QP
• Food Production 2 MS
• Food Production 2 QP
• Food Production 3 MS
• Food Production 3 QP
•  
• Trophic Levels in an Ecosystem 1 MS
• Trophic Levels in an Ecosystem 1 QP
• Trophic Levels in an Ecosystem 2 MS
• Trophic Levels in an Ecosystem 2 QP
• Trophic Levels in an Ecosystem 3 MS
• Trophic Levels in an Ecosystem 3 Q