Topic 9 - Ecosystems + Material Cycles

Question 1

What are the 4 different levels of organisation in an ecosystem?

Answer 1

Individual - single organism
Population - all organisms of one species in habitat
Community - all organisms of different species living in habitats
Ecosystem- a community of organisms with all the abiotic conditions

Question 2

How does the abiotic factor temperature affect communities?

Answer 2

Eg the distribution of bird species in Germany is changing due to rise in average temperature.

Question 3

How does the abiotic factor water affect communities?

Answer 3

Eg daisies goes best in slightly damp soils. If soil becomes waterlogged or too dry, population will decrease.

Question 4

How does the abiotic factor light affect communities?

Answer 4

Eg as trees grow + provide more shade grasses may be replaced by fungi which are better able to cope with the lower light intensity.

Question 5

How does the abiotic factor pollutants affect communities?

Answer 5

Eg lichen are unable to survive if concentration of air pollution is too high

Question 6

How does the biotic factor competition affect communities?

Answer 6

Organisms compete with other species for the same resource and if the other species gets all the food then another species competing may decrease.

Question 7

How does the biotic factor predation affect communities?

Answer 7

If the number of the predators decreases then the number of their prey will increase as fewer of them will be eaten by the predators.

Question 8

Describe the importance of interdependence in a community

Answer 8

Organisms depend on each other for things like food + shelter to survive and reproduce. This means if the change in population in one species can have knock on effects for other species in same community.

Question 9

How is the survival of some organisms dependent on other species in a mutualism relationship?

Answer 9

Mutualism is where both organisms benefit. Eg bees + plants. Bees get food from pollen + flowers get help reproducing from pollination.

Question 10

How is the survival of some organisms dependent on other species in a parasitism relationship?

Answer 10

Parasite takes what it needs to survive but host doesn’t benefit. Eg fleas feed on hosts blood but don’t offer anything in return.

Question 11

Explain how to determine the number of organisms in an area using a quadrat

Answer 11

Place quadrat on random point of area. Count all organisms interested in within the quadrat. Work out mean number of organisms per quadrat then multiply by total area of habitat.

Question 12

Explain the positive impacts of eutrophication ( an excess of nutrients in water) in an ecosystem

Answer 12

More food available. Microorganisms that feed on decomposing plants increase in number + use up oxygen

Question 13

Explain the negative impacts of eutrophication ( an excess of nutrients in water) in an ecosystem

Answer 13

Algae grow faster + block out light so plants can’t photosynthesise due to lack of light + start to decompose. Organisms that need oxygen die.

Question 14

Explain the positive impacts of fish farming on an ecosystem

Answer 14

Fish are safe from predators. Fed better. Grow better and can be treated for disease

Question 15

Explain the negative impacts of fish farming on an ecosystem

Answer 15

Disease can be more easily spread. Parasites enter fish farms + get out of control + infect fish. Less biodiverse

Question 16

How can the introduction of non indigenous species reduce biodiversity?

Answer 16

They compete with indigenous species for resources. They can out compete the indigenous species which will then die out. They can also bring new diseases that kill species -> reducing biodiversity.

Question 17

What are the impacts of reforestation?

Answer 17

Can result in lower biodiversity if only one species is replanted.
Restores deforested area.

Question 18

What are conservation schemes?

Answer 18

Help protect biodiversity by preventing species from dying out

Question 19

What are some examples of conservation schemes?

Answer 19

Protecting a species natural habitat
Protecting species in safe areas outside of natural habitat eg zoos.
Captive breeding programmes

Question 20

What are the benefits of maintaining biodiversity locally?

Answer 20

Culture- species may be important in a nation eg bald eagle USA
Ecotourism - helps bring money into biodiverse areas where conservation is taking place.
Ecotourism, conservation schemes, reforestation provides jobs.

Question 21

What are the benefits of maintaining biodiversity globally?

Answer 21

Protects human food supply as overfishing reduced fish stocks in oceans.
Ensures minimal damage to food chain.
Providing future medicines as they all come from plants.

Question 22

How do different materials cycle through the abiotic and biotic components of an ecosystem?

Answer 22

Living things are made of elements they take from environment.
They turn these elements to more complex compounds that make up living things.
Elements are passed along food chains when animals eat plants
Elements are recycled, decomposers break down waste products + elements returned to soil/air.

Question 23

What is the role of decomposers in the carbon cycle?

Answer 23

They maintain habitats for organisms. Nutrients are returned to soil for plant growth + waste material doesn’t pile up.

Question 24

How can desalination produce potable water in drought?

Answer 24

Desalination removes salts from salt water. Eg thermal desalination. Salt water is heated + water evaporates to top of vessel + travels down pipe + condenses.

Question 25

What is an ecosystem?

Answer 25

a biological community of interacting organisms and their physical environment.

Question 26

What is biodiversity?

Answer 26

A community of living organisms + non living components in their environment

Question 27

When are belt transects used?

Answer 27

To find out how organisms (plants) are distributed along a gradient.

Question 28

How do you use belt transects?

Answer 28

Mark out line in area + collect data using quadrants placed next to each other. Count all organisms of the species interested in. Repeat to find the mean number of organisms.

Question 29

How does crop rotation increase the amount of nitrates in soil?

Answer 29

Different crops grown each year in a cycle. Cycle includes a nitrogen fixing crop which helps puts nitrates back into soil for another crop to use following year.

Question 30

How do fertilisers increase the amount of nitrates in the soil?

Answer 30

Spreading manure or compost on fields recycled the nutrients in the plant/animal waste + returns them to soil through decomposition. Artificial fertilisers can be used but they’re £££

Question 31

What is the role of decomposers in nitrogen cycle?

Answer 31

Decompose proteins + urea + turn then into ammonia

Question 32

What’s the role of nitrifying bacteria in nitrogen cycle?

Answer 32

Turn ammonia in decaying matter into nitrites and then into nitrates

Question 33

What’s the role of nitrogen fixing bacteria in nitrogen cycle?

Answer 33

Turn atmospheric N2 into ammonia which forms ammonium ions

Question 34

What’s the role of denitrifying bacteria in nitrogen cycle?

Answer 34

Turn nitrates back into N2 gas. Usually found in waterlogged soils.