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Edexcel GCSE Biology (9-1) > Topic 9 - Ecosystems and Material Cycles > Flashcards

Topic 9 - Ecosystems and Material Cycles Flashcards

1
Q

9.1 - Outline the levels of organization in an ecosystem

A

Individual
Population
Community
Ecosystem

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2
Q

9.1 - Define population

A

All organisms of identical species living together in a habitat

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3
Q

9.1 - Define community

A

All populations of different species living together in a habitat

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4
Q

9.1 - Define ecosystem

A

Community of organisms and non living (abiotic) components of an area and their interactions.

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5
Q

9.2 - What are some abiotic factors? Give some examples

A

The non living aspects of an ecosystem like temperature,water availability,light intensity and pollutants.

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6
Q

9.2 - Describe how communities are affected by environmental conditions

A

Environmental conditions can affect the distribution and abundance of organisms within communties.

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7
Q

9.2 - Describe how communities are affected by temperature ( abiotic )

A

Plants and animals grow best at their optimum temperature.

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8
Q

9.2 - Describe how communities are affected by water availability( abiotic )

A

Water is needed for survival, if there is water deficit, producers can’t photosynthesize and animals can’t get the water and the food ( producers ) it needs.

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9
Q

9.2 - Describe how communities are affected by light intensity ( abiotic )

A

Affects rate of photosynthesis in producers ( like plants ) which is a source of food and shelter for other organisms.

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10
Q

9.2 - Describe how communities are affected by moisture levels ( abiotic )

A

Animals and plants both are adapted to growing in the atmospheres moisture.Too much moisture can lead to water logging of plants meaning they can’t respire so it dies.

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11
Q

9.2 - Describe how communities are affected by soil pH and mineral content ( abiotic )

A

Plants are sensitive to pH, some plants like heathers grow best in acidic condition although lavender grows better in alkaline conditions.

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12
Q

9.2 - Describe how communities are affected by wind intensity and direction ( abiotic )

A

Wind can increase carbon dioxide supplied to plants
Wind increases transpiration rate, water is the product from transpiration and moisture moves with the wind so fresh air can replace it leading to more transpiration and leading to more water loss

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13
Q

9.2 - Describe how communities are affected by carbon dioxide level( abiotic )

A

C02 required for photosynthesis, as concentration of C02 increases, so does rate of photosynthesis, promoting growth.
Plants in greenhouses have higher carbon dioxide for increased growth.
C02 is acidic and may not be suitable for all plants

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14
Q

9.2 - Describe how communities are affected by oxygen levels ( abiotic )

A

Oxygen is required for respiration of animals and producers, moving lakes have high concentration of oxygen while stagnant lakes have low oxygen concentration.

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15
Q

9.2 - Describe how communities are affected by new predators ( biotic )

A

Balanced ecosystems have prey and predators evolving together, and new predator disrupts the food chain by eating prey which isn’t theirs.

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16
Q

9.2 - Describe how communities are affected by diseases ( biotic )

A

Organisms in new ecosystems can bring new pathogens, killing local population.

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17
Q

9.3 - Organisms in a community are “interdependent”. What does this mean? Give some examples

A

Organisms dependent on each other, this also means if the population or factors of one species changes is affects other species in that community.
Plants depend on pollinators like bees
Herbivores depend on plants to eat
Animals depend on mates

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18
Q

9.4 - Describe symbiotic relationship

A

Relationship between two species living together

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19
Q

9.4 - Describe commensal

A

Interaction between two organisms where there is no damage to either species, but one of the species benefits.

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20
Q

9.4 - Describe mutualism

A

Interaction between two organisms where they both benefit because of their relationship

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21
Q

9.4 - Describe parasitism

A

Interaction between two organisms, where only one organisms, the parasite, benefits while the host doesn’t

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22
Q

9.5 - What is a quadrat?

A

Measures abundance and distribution of organisms in an area

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23
Q

9.5 - What is a belt transect?

A

Measures the distribution of organisms across a gradient

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24
Q

9.6 - How to determine organisms in a given area using data with quadrats and belt transects

A

Divide field into 100 equal squares
Randomly select a square and place quadrat on it
Count abundance of organisms in the square
Do this 5 times, averaging the results
Multiply average by 100 to find the clovers on a field

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25
Q

9.7B - What do food chains and their arrows show?

A

They describe feeding relationships between organisms and the total mass of living material/biomass transfer
Arrows show direction of biomass/total mass of living material transfer

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26
Q

9.7B - What are trophic levels?

A

They are the divided stages in a food chain

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27
Q

9.7B - What is a food chain made up of?

A

Producer
Primary Consumer
Secondary Consumer
Tertiary Consumer

28
Q

9.7B - Why are producers the first trophic level?

A

Producers provide food and biomass to supply the whole food chain and the rest of the food chain is the transfer of this biomass.

29
Q

9.7B - What does a pyramid of biomass show and why is it usually pyramid shaped?

A

The pyramid represents the dry mass of living material at each trophic level of a food chain
The pyramid shape.is because producers have most biomass so longest bar, as you move up the food chain biomass is lost so the bars decrease in length.

30
Q

9.7B - Why is biomass lost between trophic levels of food chain? And therefore why are there rarely more than 4 trophic levels?

A

Glucose used for respiration in plants
Respiration generates heat energy which is lost to surroundings
Some parts of organisms can’t be eaten
Excretion
As the energy decreases through trophic levels after 4 levels the energy is insufficient to support breeding.

31
Q

9.8B - What is the equation for calculating efficiency of biomass transfer between trophic levels?

A

Efficiency =Biomass available after transfer/Biomass before transfer *100

32
Q

9.9 - What is biodiversity?

A

Variety of living organisms in an ecosystem

33
Q

9.9 - Explain the impacts fish farming has on biodiversity?

A

Food for fish can pollute the water which causes eutrophication
Parasites from fish farms can spread and contaminate surroundings
Other marine animals can be tangled in the netting

34
Q

9.9 - How does fertilizer use cause eutrophication and affect biodiversity?

A

Fertilizers get washed into water sources and the nutrients build in the water,the algae blocks sunlight and so aquatic plants can’t photosynthesise and die.Decomposers deplete more oxygen as they break down dead plants and leads to animals not being able to respire aeorbically and die.This causes lots of death and therefore reducing biodiversity

35
Q

9.9 - How does the introduction of non-indigenous species affect biodiversity?

A

Could out-compete native species, leading to reduction in population
Native species can become prey of non-indigenous species
They could bring diseases, killing lots of the native species, reducing biodiversity.

36
Q

9.9 - How does fertilizer use cause eutrophication and affect biodiversity?

A

Fertilizers get washed into water sources and the nutrients build in the water,the algae blocks sunlight and so aquatic plants can’t photosynthesize and die.Decomposers deplete more oxygen as they break down dead plants and leads to animals not being able to respire aerobically and die.This causes lots of death and therefore reducing biodiversity

37
Q

9.10 - What are the benefits of reforestation?

A

The replanting of forests are beneficial to re-create habitats and restore biodiversity

38
Q

9.10 - What are the benefits of conservation schemes for biodiversity?

A

Prevent extinction of species while increasing population numbers, which maintains biodiversity.
Increases chance of species adapting to environmental changes as there is more population
Some plant species yet to be found and may contain chemicals which could be used in future medicine
Safeguards valuable future resources like fuels and paper
Country’s aesthetics look nicer and can boost culture and ecotourism
And jobs can be provided through ecotourism, reforestation and conservation schemes.

39
Q

9.11B - What is food security?

A

Ensuring people have adequate and safe food to eat

40
Q

9.11B - Explain some biological factors affecting food security

A

Rising human population
Increased meat farming and consumption
Impact of new pests and pathogens
Environmental change caused by human activity
Sustainability issues (like use of agricultural land for biofuel production)

41
Q

9.11B - How does rising human population affect food security?

A

As human population increases the global food production must increase to meet growing demand of food.

42
Q

9.11B - How does increased meat farming and consumption affect food security?

A

More consumption of meat and fish in wealthier areas of the world
Less energy and biomass in livestock than crops as everything is getting consumed
Livestock use land for grazing on crops which humans could consume
Less food available for humans and reduces food security

43
Q

9.11B - How does new pests and pathogens affect food security?

A

Pests and pathogens can reduce and destroy crop yield which can reduce food security

44
Q

9.11B - How does sustainability affect food security?

A

Unsustainable farming disrupts food chains and decreases ability to meet future food requirements.
However many low economically developed areas can’t maintain modern farming methods due to high costs.
Using land for bio-fuel reduces land available for crops

45
Q

9.11B - How does environmental change due to human activity affect food security?

A

Greenhouse gas emissions are linked with global warming which can affect crop growth
Salinisation (accumulation of water in soil) reduces agricultural potential of soil.

46
Q

9.12 - What are the three types of nutrients cycles? Explain why these are

A

Carbon cycle
Water cycle
Nitrogen cycle

47
Q

9.12 - Why are the nutrient cycles important?

A

Carbon,water and nitrogen are essential to life
There is a fixed amount of materials that must be recycled continuously.

48
Q

9.12 - How do materials cycle through abiotic and biotic components of an ecosystem?

A

Organsims take in elements from surroundings
Elements converted into complex molecules which becomes biomass
Elements moved along food chain
Elements returned to environment during excretion and decomposition of dead animals

49
Q

9.13 - Describe the stages of the carbon cycle

A

Photosythesising removes CO2 from atmosphere
Eating passes carbon compounds through the food chain
Respiration in plants and animals return CO2 to atmosphere
Organisms die and decompose, decomposers like bacteria and fungi release CO2 via respiration while decomposing.
Combustion and burning of materials like wood and fuels release CO2.

50
Q

9.14 - Describe the stages of the water cycle

A

Energy from sun evaporates water from water sources, transpiration also releases water vapour.
Water vapour rises, cools and condenses to form clouds, soon there is precipitation.
Water is absorbed by soil and taken up roots, some water used in photosythesis or in a part of the plant, entering the food chain.
Excretion returns water to soil and surface runoff returns water to water sources (etc.seas).

51
Q

9.14 - What is potable water and how can it be prepared?

A

Potable water is water that is safe to drink, it can be prepared via desalination.

52
Q

9.14 - What is desalination and what are the two methods of it?

A

Desalination is the process of removing salt from saline(mixture of salt and water) water.
There are two methods of desalination:
Thermal desalination - Saline water boiled, water evaporates, rises and condenses down a pipe, separating pure water from salts.
Reverse osmosis - Saline water pumped into a vessel which has a partially permeable membrane at high pressure.
High pressure forces water molecules to move from high salt concentration to an area of low salt concentration.
This slowly separates pure water from the salts.

53
Q

9.15 - What do plants use to make proteins and why can’t it be directly used to form proteins?

A

Plants use nitrates to make proteins, these nitrates are unreactive and so can’t be used directly in reactions.

54
Q

9.15 - Name the four types of bacteria involved in the nitrogen cycle and their functions

A

Decomposers - Breaks down proteins and urea into ammonia which dissolves into solution making ammonium ions.
Nitrogen fixing bacteria - Convert nitrogen gas into ammonia which dissolves into solution making ammonium ions.
Nitrifying bacteria - Converts ammonium ions into nitrites which are converted into nitrates.
Denitrifying bacteria - Converts nitrates into nitrogen gas.

55
Q

9.15 - What type of relationship is between nitrogen fixing bacteria and legumes?

A

There is a mutualistic relationship as plants receive ammonium ions from bacteria and bacteria gain sugars from the plant.

56
Q

9.15 - Describe the stages of nitrogen cycle

A

Nitrogen fixing bacteria convert nitrogen gas to ammonia which dissolves to form ammonium ions.
Nitrifying bacteria convert ammonium ions to nitrate ions which are taken up by plants and used to build proteins.
Feeding passes nitrogen through the food chain.
Organisms die and decompose.Decomposers break down proteins and urea to form ammonia which dissolves to form ammonium which dissolves to form ammonium ions.
Denitrifying bacteria convert nitrates in the soil back to nitrogen gas.

57
Q

9.15 - How can the nitrate content in the soil be increased?

A

Fertilisers like manure, compost and artificial fertilisers have nitrates in the soil.
Crop rotation replenishes nitrates depleted by previous crop, this can be done by planting a nitrogen fixing crop.

58
Q

9.15 - What is decomposition and how does it decompose?

A

Process of breaking down dead materials into simpler organic matter.
Decomposition is done by releasing enzymes that catalyse the breaking down of dead material into smalller molecules.

59
Q

9.16B - What is indicator species?

A

Species which presence or absence in an environment provide indication of environmental conditions such as pollution or water purity.

60
Q

9.16B - What indicator species can be used to identify the quality of water?

A

Bloodworms and sludgeworms are adapted to living in polluted water, therefore its presence means the water is polluted.
Freshwater shrimps and stoneflies are sensitive to oxygen concentrations and water has a constant water concentration so survives in clean water, therefore the presence of these two species means the water is clean.

61
Q

9.16B - Evaluate the use of indicator species as a measure of pollution

A

Indicator species are cheaper, simpler and can monitor pollution over long lengths of time.However it is less accurate of technology like electronic meters and don’t give a definite figure for pollution levels.

62
Q

9.16B - What indicator species can be used to identify the quality of air?

A

Blackspot fungus found on rose leaves are sensitive to sulfur dioxide concentrations so can only survive in clean air, therefore the presence of it means clean air.
Lichens monitor air pollution and are sensitive to the concentration of sulfur dioxide.Different lichens grown in different levels of air pollution such as bushy lichens in cleaner air and crusty lichens in polluted air. More abundance and distribution of lichens indicate cleaner air.

63
Q

9.17B - Explain what factors affect rate of decomposition

A

Oxygen availability - Oxygen is required for aerobic respiration of the plants, therefore as oxygen levels increase so does decomposition and as it decreases so does decomposition. However this doesn’t apply to all decomposers, some can respire anaerobically but will be slower as anaerobic respiration produces less energy.
Temperature - Decomposers release enzymes and 50°C is its optimum temperature.Lower, and enzymes work slowly, rate of decomposition decreases.Higher, and enzymes denature, decomposition stops.
Water content - The soils’ water content affects decomposers as they need water to survive, therefore in moist conditions rate of decomposition is high but in waterlogged soils there is not a lot of oxygen for respiration so rate of decomposition decreases.

64
Q

9.17B - Describe methods of food storage to slow rate of decomposition

A

Store food in fridge or freezer to slow microbial activity
Stored in airtight cans to prevent entry of microorganisms
High temperatures for sterilising cans and destroying bacteria
Adding salt or sugar to food, which kills microbes (lose water by osmosis)
Food kept dry to reduce ability of microorganisms to survive

65
Q

9.18B - What conditions required to make compost?

A

Conditions with high rate of decomposition such as oxygen,warmth and moisture
As temperature,water content and oxygen availability are at the best amount to aid rate of decomposition, the compost will be more impactful on soil fertility.

66
Q

9.19B - How do you calculate rate changes in decay of biological materials?

A

Rate of decomposition = mass lost / number of days
g/day = g/day

Edexcel GCSE Biology (9-1) (9 decks)

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