Crop plants and fish

Question 1

Advantages of organic fertilisers
(don’t need to know)

Answer 1

Improves soil structure
Greater range of minerals such as nitrates for proteins and magnesium for chlorophyll.
Releases minerals over a longer period of time.
Less costly for farmer (already available on farm)

Question 2

Disadvantages of organic fertilisers
(don’t need to know)

Answer 2

Slow acting - has to decompose first
Bulkier, harder to apply to soil than inorganic
May contain pests

Question 3

Advantages of inorganic fertilisers
(don’t need to know)

Answer 3

Fast acting - mineral ions release immediately
Contents known
Easy to apply

Question 4

Disadvantages of inorganic fertilisers
(don’t need to know)

Answer 4

Can lead to eurtophication as fertiliser is soluble
Requires regular reapplication

Question 5

Advantages of pesticides

Answer 5

Easily accessible and relatively cheap
Have an immediate effect
Kills the entire population of pests

Question 6

Disadvantages of pesticides

Answer 6

Pests can develop resistance to them.
Non specific chemicals so can often kill other beneficial organisms (pollinating insects)
Chemicals can concentrate and accumulate at the top of the food chain, harming top predators.
Leaves residue on crop/eaten by humans.
Need for regular application so costly.

Question 7

What pesticide kills insect pests?

Answer 7

Insecticides

Question 8

What pesticide kills plant pests?

Answer 8

Herbicides

Question 9

What pesticide kills fungal pests?

Answer 9

Fungicides

Question 10

Give a brief description of how biological control happens

Answer 10

A species is introduced specifically to prey on the pest species. They never completely remove a pest, but keep it at lower levels. This can happen naturally.

Question 11

Advantages of biological control

Answer 11

Pest will not become resistant.
Can target specific species, will only kill the pest.
Long lasting/doesn’t need reapplication.
No bioaccumulation
No residue on crop/not eaten by humans.

Question 12

Disadvantages of biological control

Answer 12

Takes a long time to reduce pest population.
Cannot kill an entire population, some pests will always be present.
May not adapt to new environment.

Question 13

Benefits of fish farming

Answer 13

Ability to selectively breed fish to ensure high-quality, fast-growing fish.
Can protect against predators.
Ability to control water quality.
Ability to control feeding to ensure rapid growth.

Question 14

Explain how water quality is managed in fish farming

Answer 14

Water is filtered to remove waste and harmful bacteria to prevent diseases. Water is also cleaned to maintain high levels of oxygen for aerobic respiration.

Question 15

Explain how diseases are controlled during fish farming

Answer 15

Antibiotics are given to fish to prevent spread of diseases which could otherwise spread quickly due to their close confinement. Kept in small numbers to minimise spread of disease. Higher chances of survival.

Question 16

Explain how removal of waste products is used in fish farming

Answer 16

Water can be filtered to remove waste products such as faeces and sewage. Fences, nets, tanks are cleaned or location of fish is changed to ensure clean water.

Question 17

Explain how quality and frequency of feeding is used in fish farming

Answer 17

Food is high in nutrients to ensure fast growth.
Fed frequently but in small amounts so they don’t overeat or start eating each other.

Question 18

Explain how selective breeding is used in fish farming

Answer 18

Fish are separated by gender so farmers can choose to only allow fish with desired characteristic to reproduce (selective breeding). Ensures that the stock of fish is fast growing as these genes get passed on more frequently.

Question 19

Define interspecific predation

Answer 19

Predation between different species.

Question 20

Explain how interspecific predation is controlled in fish farming

Answer 20

Different species of fish are separated by fences, nets and tanks to prevent fighting.

Question 21

Define intraspecific predation

Answer 21

Predation within the same species

Question 22

Explain how intraspecific predation is controlled in fish farming

Answer 22

Fish are separated by size and age so they don’t eat each other or fight.

Question 23

Explain how greenhouses and polythene tunnels provide enhanced conditions for plants to grow

Answer 23

Transparent material allows natural light in for sufficient photosynthesis.
Greenhouse effect raises temperature.
Burning fossil fuels or wood increases temperature when external temperature is too low, also provides carbon dioxide and water vapour.
Water vapour maintains a moist atmosphere so reduces water loss by transpiration.
This increases rate of photosynthesis so increases the yield.

Question 24

Benefits of selective breeding

Answer 24

Desirable characteristics emerge faster.
Humans can choose desirable characteristics.

Question 25

Problems with selective breeding

Answer 25

Population is more susceptible to disease. Reduces variation.

Question 26

Describe how you would selectively breed large cows

Answer 26

Select cows with largest mass and mate them. Select offspring with largest mass and mate them. Repeat over many generations

Question 27

Describe how you would selectively breed crops that give biggest yield

Answer 27

Breed parents plants with highest yield. Select offspring with highest yield and breed them. Repeat over many generations

Question 28

How do fertilisers lead to increased crop yield?

Answer 28

Provide nitrates for growth as they produce amino acids and proteins. Provides magnesium for chlorophyll, to increase photosynthesis and production of glucose. Provides phosphates for DNA.