Ecology

Question 1

What is meant by the term population?

Answer 1

All the organisms of one species living in a habitat.

Question 2

What is meant by community?

Answer 2

The population of different species living in a habitat.

Question 3

What is a stable community?

Answer 3

A community in which all species and environmental factors are in balance so the population sizes are roughly constant.

Question 4

What is the ecosystem?

Answer 4

The interaction of a community of organisms and the parts of their environment that are non-living.

Question 5

What is meant by the term interdependence?

Answer 5

Where each specie in a community depend upon other species for things such as food, shelter, pollination and seed dispersal.

Question 6

What is meant by the term biotic?

Answer 6

Living.

Question 7

What is meant by the term abiotic?

Answer 7

Non-living.

Question 8

What biotic factors can affect organisms in a community?

Answer 8

> new predators.
food availability.
new pathogens.
competition.

Question 9

What abiotic factors can affect organisms in a community?

Answer 9

> light intensity.
> wind intensity and direction.
> CO₂ level (for plants).
> moisture level.
> temperature.
> O₂ level (for aquatic animals).
> soil pH and mineral content.

Question 10

What is meant by the term extremophiles?

Answer 10

organisms that are adapted to live in extreme conditions such as high temperature, high pressure or high salt concentration.

Question 11

Who is included in a food chain?

Answer 11

producer ⟶ primary consumer ⟶ secondary consumer ⟶ tertiary consumer.

Question 12

What is the producer in a food chain?

Answer 12

A plant or algae that makes glucose by photosynthesis.

[all food chains start with a producer]

Question 13

What is the primary consumer in a food chain?

Answer 13

An animal that eats producers and may be eaten by secondary consumers.

Question 14

What is a secondary consumer in food chains?

Answer 14

An animal that eats primary consumers and may be eaten by tertiary consumers.

Question 15

What is a predator?

Answer 15

A consumer that kills and eats other animals also know as prey.

Question 16

What is meant by the term biomass?

Answer 16

The mass of living material.

[energy stored in biomass is transferred along food chains and used by the other organisms to build biomass]

Question 17

What is the predator-prey cycle?

Answer 17

∞ prey population increases ⟶ predator population increases ⟶ prey population decreases ⟶ predator population decreases ∞

Question 18

What is meant by the term biodiversity?

Answer 18

The variety of different species on Earth or within an ecosystem.

Question 19

What is meant by the term global warming?

Answer 19

The gradual heating up of the Earth as a result of increasing levels of greenhouse gases in the atmosphere.

Question 20

What are three consequences of global warming?

Answer 20

> rising sea levels so low levelled places may flood.
change in the distribution of some organisms.
decrease in biodiversity as some species may become extinct.

Question 21

What is meant by the term deforestation?

Answer 21

The cutting down of forests.

Question 22

Why may pollution be harmful?

Answer 22

an increasing human population and standard of living.
⤷ more resources used more quickly ⟶ more plants and animals killed so less biodiversity.
or
⤷ more waste produced ⟶ more pollution ⟶ more plants and animals killed so less biodiversity.

Question 23

What are the three ways we pollute the environment?

Answer 23

> sewage, fertilisers and toxic chemicals such as pesticides from farming and industry get washed into water.
smoke and acidic gases.
waste dumped in landfill sites pollute land.

Question 24

What are the five programmes to protect ecosystems?

Answer 24

> breeding programmes.
↳ endangered species are bred in captivity to make sure the species survive.
habitat restoration.
↳ rare habitats like mangroves, heathland and coral reefs are protected and regenerated.
hedgerow and field margins.
↳ these are reintroduced around the fields where only a single crop type is grown, creating habitats for more organisms.
government regulations.
↳ such as to reduce deforestation and CO₂ emissions.
recycling.
↳ reduces the amount of waste going to landfill sites.

Question 25

What happens during the water cycle?

Answer 25

❶ energy from the sun makes water evaporate from the land and sea turning it into water vapour.
↳ water also evaporates from plants which is known as transpiration.
❷ the warm water vapour is carried upwards as warm air rises.
❸ as it gets higher up, it cools and condenses to form clouds.
❹ water falls from the clouds as precipitation onto land where it provides fresh water for plants and animals.
❺ it then drains into the sea before the whole process starts again.

Question 26

Why is the water cycle important?

Answer 26

It means that water is endlessly recycled.

Question 27

How are elements cycled back to the start of the food chain?

Answer 27

Through decay.

Question 28

How are materials returned to the environment?

Answer 28

In waste products or when the organisms die and decay.

Question 29

How do materials decay?

Answer 29

They’re broken down by microorganisms. This happens faster in warm, moist, aerobic conditions because microorganisms are more active in these conditions.

Question 30

What happens during the carbon cycle?

Answer 30

❶ CO₂ is removed from the atmosphere by green plants and algae during photosynthesis.
↳ the carbon is used to make glucose which is turned into carbohydrates, fats and proteins that make up the bodies of the plants and algae.
❷ when the plants and algae respire, some carbon is returned to the atmosphere as CO₂.
❸ when the plants and algae are eaten by animals, some carbon becomes part of the fats and proteins in their bodies, then the carbon moves through the food chain.
❹ when the animals respire, some carbon is returned to the atmosphere as CO₂.
❺ when plants, algae and animals die, other animals and microorganisms feed on their remains and when they respire, CO₂ is returned to the atmosphere.
❻ animals also produce waste that is broken down by detritus feeders and microorganisms.
❼ the combustion of wood and fossil fuels also release CO₂ back into the air.

Question 30

What does anaerobic decay produce?

Answer 30

Methane gas.

Question 31

When can biogas generators be used?

Answer 31

To produce methane gas as a fuel.

Question 32

What may plants compete for?

Answer 32

> light.
space.
water and mineral ions from the soil.

Question 33

What may animals compete for?

Answer 33

> space (territory).
food.
water.
mates.

Question 34

What factors affect the rate of decay?

Answer 34

> temperature.
water availability.
oxygen availability.
number of decay organisms.

Question 35

How does temperature affect the rate of decay?

Answer 35

> warmer temperatures make things decompose quicker as they increase the rate the enzymes work at.
if it’s too hot, decomposition slows down or stops as the enzymes are destroyed and the organisms die.
really cold temperatures also slow it down.

Question 36

How does water availability affect the rate of decay?

Answer 36

Decay takes place faster in moist environments as the organisms involved in decay need water to carry out biological processes.

Question 37

How does oxygen availability affect the rate of decay?

Answer 37

Many organisms need oxygen to respire which is needed to survive. The microorganisms involved in anaerobic decay don’t need oxygen.

Question 38

How does the number of organisms affect the rate of decay?

Answer 38

The more microorganisms and detritus feeders there are the faster the decomposition.

Question 38

How does the number of organisms affect the rate of decay?

Answer 38

The more microorganisms and detritus feeders there are the faster the decomposition.

Question 39

How is pollution harmful?

Answer 39

It kills plants and animals which can reduce biodiversity.

Question 40

How do humans reduce the amount of land available for other animals and plants?

Answer 40

> building.
quarrying.
farming.
dumping waste.

Question 41

What are peat bogs?

Answer 41

Areas of land that are acidic and waterlogged.

[plants that live in bogs don’t fully decay when they die as theres not enough oxygen]

Question 42

How are peat bogs harmful to the environment?

Answer 42

When it is drained, it comes in contact with air and some microorganisms start to decompose it and when they respire using oxygen, they release carbon dioxide contributing to global warming.

Question 43

What happens when the peat bogs are destroyed?

Answer 43

Also destroys or reduces the area of the habitats of some of the animals, plants and microorganisms that live there reducing biodiversity.

Question 44

What are the consequences of global warming?

Answer 44

> rising sea levels.
changes in species distribution.
changes in migration patterns.
reduction in biodiversity.

Question 45

What are the effects of sea levels rising?

Answer 45

> higher temperatures cause seawater to expand and ice to melt causing the sea level to rise.
leads to flooding resulting in loss of habitats.

Question 46

Describe pyramids of biomass.

Answer 46

> each bar shows the relative mass of living material at a trophic level.
↳ how much all the organisms at each level would “weigh” if you put them all together.
the one on top would have a small biomass where the ones below will have a big biomass.
the big bar at the bottom shows trophic level 1.
the next bar will be the primary consumer then the secondary consumer and so on up the food chain.

Question 47

Why is biomass lost between the different trophic levels?

Answer 47

> not all the ingested material is absorbed as some is digested as faeces.
some absorbed material is lost as waste such as carbon dioxide, water in respiration and water and urea in urine.

Question 48

How much biomass from each trophic level is transferred to the level above it?

Answer 48

10%.

Question 49

What is the formulae to calculate the efficiency of biomass transfer?

Answer 49

efficiency = biomass transferred to the next level / biomass available at the previous level x 100.

Question 50

What is food security?

Answer 50

Having enough food to feed a population.

Question 51

What are the biological factors that affect levels of food security?

Answer 51

> the increasing birth rate threatens food security in some countries.
changing diets in developed countries means scarce food resources are transported around the world.
new pests and pathogens that affect farming.
environmental changes that affect food production such as widespread famine occurring in some countries if rains fail.
the cost of agricultural inputs.
conflicts that have arisen in some parts of the world which affect the availability of water or food.

Question 52

How can the efficiency of food production be improved?

Answer 52

By restricting energy transfer from food animals to the environment which can be done by limiting their movements and by controlling the temperature of their surroundings.