Energy Flow

Question 1

What does population mean?

Answer 1

All of the organisms of a particular species found in an ecosystem.

Question 2

What does community mean?

Answer 2

All the different species living in an ecosystem.

Question 3

What does habitat mean?

Answer 3

A place within an ecosystem where specific organisms live.

Question 4

What does ecosystem mean?

Answer 4

A self-supporting system of organisms interacting with each other and their physical environment.

Question 5

What is a producer?

Answer 5

An organism that can make its own food.

Question 6

What is a primary consumer?

Answer 6

An organism that gets its energy by feeding on producers.

Question 7

What is a secondary consumer?

Answer 7

An organism that gets its energy by feeding on primary consumers.

Question 8

What is a tertiary consumer?

Answer 8

An organism that gets its energy by feeding on secondary consumers.

Question 9

What is a decomposer

Answer 9

An organism that decomposes organic material (e.g. microorganism).

Question 10

What is a top carnivore?

Answer 10

An organisms that has no natural predators.

Question 11

Why is it an advantage for an animal to feed on more than one type of organism?

Answer 11

• The animal can feed in different seasons.
• The animal has less competition for food and is less likely to die of starvation.
• The animal has a balanced diet.

Question 12

Why are there rarely more than five trophic levels?

Answer 12

• Energy is always lost in ways such as:
- movement
- respiration
- excretion
- egestion
- death
• Little energy will reach the top of the food chain.

Question 13

How can students using a quadrant to estimate population size make their results more reliable?

Answer 13

• Make the placing of the quadrat random.
• Use a larger number of quadrats.
• Calculate the percentage cover.

Question 14

What is biological control?

Answer 14

When natural predators of pests are introduced to reduce the number of pests in a farm.

Question 15

What are the disadvantages of using pesticides?

Answer 15

• They can affect the taste of a crop / poisonous to humans.
• Can affect other species.
• Bioaccumulation - pesticides are stored in fatty tissue.
• Disrupt the food chain.
• Needs to be reapplied often.
• Pests can develop a resistance.

Question 16

What are the advantages of using pesticides?

Answer 16

• They kill and destroy pests/insects.

* Increase the yield of plants by reducing the amount of crop that is eaten.

Question 17

How do insect pests affect crop yield?

Answer 17

• Yield is reduced because the crop/leaf is eaten.
• Less leaf, less light is trapped and less carbon dioxide is absorbed.
• Less photosynthesis.

Question 18

What are the advantages of biological pest control compared to using pesticides?

Answer 18

• There is no resistance developed to the pesticides - will always work.
• No collateral damage to other species/food chains.
• Does not need to be reintroduced every so often - longer lasting.
• No pollution/harm to the environment.

Question 19

Why is it important for water to circulate through fish cages?

Answer 19

• Waste can be removed (e.g. faeces, urine).
• Oxygen can flow - no stagnation.
• Respiration can happen all the time.

Question 20

Why do fish farmers supply small amount of food at regular intervals?

Answer 20

Less eutrophication because all the food is eaten.

Question 21

Why do fish farmers want a high food conversion efficiency?

Answer 21

• Fish growth is larger.
• Small amount of food provides greatest amount of weight put on.
• Economic benefit is maximised.

Question 22

How can fish farmers reduce competition between the same species of fish?

Answer 22

• Cage size can be increased.
• Food supply is ensured to be sufficient.
• Different sizes/ages of fish are separated.

Question 23

How can fish farmers reduce competition between different species?

Answer 23

• Only one species of fish is put in each cage.

* Cages are covered using mesh or other things.

Question 24

Why are fish good sources of food for humans?

Answer 24

They contain:

• omega 3
• fats/fatty acids
• protein
• vitamin (D)

Question 25

How do fish farmers maintain water quality? (4)

Answer 25

• Oxygen is bubbled through cages.
• Waste, such as algae, is removed by the water being filtered/replaced.
• Food is fed in small and regular intervals to prevent a build up of food.
• Antibiotics / dead and ill fish removed / fungicide to prevent diseases and spread of bacteria/fungi.

Question 26

How might a fish farm harm an ecosystem?

Answer 26

• Things such as faeces and mineral ions are released.
• Chemicals are released.
• Bacteria is released, which could cause oxygen depletion.
• Diseases might affect wild fish.
• Predators are attracted.
• Building cages could destroy habitats.

Question 27

Why might a farmer have a fish farm instead of catching fish in the wild?

Answer 27

• A harvest is guaranteed.
• No need to buy a boat/employ fishers/buy nets.
• Not dangerous.
• Wild fish stocks are not depleted/endangered species are conserved.
• Selective breeding can ensure a good yield.
• All fish are the same species/health/size/age.

Question 28

How could a fish farmer increase the yield of fish?

Answer 28

• Selective breeding to maximise yield.
• Antibiotics can be added to prevent parasites killing fish.
• Diet can be controlled to grow fish to their maximum size.
• Water quality can be controlled to filter out nitrogenous water.

Question 29

Why might a species (e.g. grey squirrels) increase in number compared to another species (e.g. red squirrels)?

Answer 29

• Fewer predators.
• Better camouflage.
• Better disease resistance.
• More reproduction.
• Better competitors.