5.1.2 Crop Plants: Increasing Yield

Question 1

Fertilisers increase the amount of key nutrients in the soil for crop plants. How does this benefit the crop plants?

Answer 1

They can grow larger and are more healthy, which increases yields

Question 2

Pesticides – these chemicals kill off unwanted insects and weed species. How does this benefit the crop plants?

Answer 2

Less damage done to crop plants by insects, as well as reducing competition from other plant species, which increases yields

Question 3

What do plants require from fertilisers to grow well?

Answer 3

A range of mineral ions

Question 4

As crop plants take up these mineral ions from the soil, the mineral ions need to be replaced if what?

Answer 4

If crops are grown repeatedly in the same field (i.e. year after year)

Question 5

What are used to replace these mineral ions?

Answer 5

Fertilisers

Question 6

Name 2 things that fertilisers make crops do, so that yields are increased

Answer 6

Grow faster and bigger

Question 7

Name 2 forms of fertiliser

Answer 7

organic fertiliser chemical fertiliser

Question 8

Organic fertilisers commonly used by farmers include what?

Answer 8

Farmyard manure and compost

Question 9

Chemical fertilisers are often applied to the soil as what?

Answer 9

Dry granules or can be sprayed on in liquid form

Question 10

What are the 3 main substances that they provide to the crop plants?

Answer 10

Nitrogen
Phosphorous
Potassium

Question 11

Nitrogen is absorbed in the form of what?

Answer 11

Nitrates

Question 12

Nitrogen is needed to make amino acids which are the building blocks of what?

Answer 12

Proteins

Question 13

Lack of nitrogen causes what?

Answer 13

Weak growth and yellowing of the leaves of plants

Question 14

Phosphorous is absorbed in the form ofwhat?

Answer 14

Phosphates

Question 15

Phosphorous is needed to make DNA and what?

Answer 15

Cell membranes

Question 16

Lack of phosphorus can cause what?

Answer 16

Poor root growth and discoloured leaves

Question 17

Potassium is absorbed in the form of various what?

Answer 17

Compounds of potassium

Question 18

Potassium allows enzyme reactions to take place to produce ATP in what?

Answer 18

Respiration

Question 19

Potassium needed for the enzymes involved in what?

Answer 19

Photosynthesis

Question 20

Lack of potassium can cause what?

Answer 20

Poor growth of flowers and fruits

Brown spots on leaves

Question 21

Pests such as insects and other animals can damage crops by what?

Answer 21

Eating them

Question 22

Weeds can outcompete crop plants for space, and what 2 other factors?

Answer 22

Water and soil nutrients

Question 23

Fungi can infect crop plants and spread disease which can what?

Answer 23

Affect growth and yield

Question 24

All of these can be controlled by using pesticides (chemical control) or what?

Answer 24

By introducing other species (biological control)

Question 25

What are 3 different types of pesticides, and what do they kill?

Answer 25

Insecticides - kill insect pests Herbicides - kill plant pests Fungicides - kill fungal pests

Question 26

What are 3 advantages of pesticides?

Answer 26

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

Question 27

What are 3 disadvantages of pesticides?

Answer 27

Organisms that are meant to kill can develop resistance They are non specific chemicals and can often kill other organisms eg. Bees, that are beneficial to polination They can be persistent chemicals that don't break down in the body, can accumlate at the top of the food chain and harm top predators (bioaccumulation)

Question 28

Biological control can happen naturally, eg. ladybirds eat what?

Answer 28

Aphids

Question 29

Usually, a species is introduced specifically to prey on the pest species – for example, parasitic wasps can control what?

Answer 29

Whitefly in glasshouse tomato crops

Question 30

As they are based on a predator-prey cycle, they do not completely remove a pest, but what?

Answer 30

Keep it at lower levels

Question 31

What are 5 advantages of biological control?

Answer 31

Natural method (no pollution) No resistence Can target specific species Longer lasting Does not need to be repeatedly applied

Question 32

What are 5 disadvantages of biological control?

Answer 32

May eat other organisms instead of the pest takes longer to be effective Cannot kill aa. Some pests will always be present May not adapt to new envoronment or move out of area May become a pest itself