Food Supply, Plant Growth and Productivity

Question 1

What are the 3 aspects of food security?

Answer 1

1. Access to food
2. Quantity of food
3. Quality of food

Question 2

What has caused a demand for increased food production?

Answer 2

Increase in human population & concern for food security

Question 3

What process is all food production ultimately dependent on?

Answer 3

Photosynthesis

Question 4

Give some examples of plant crops.

Answer 4

cereals, potato, roots and legumes.

Question 5

State some factors that will increase food production.

Answer 5

1. breeding for higher yielding cultivars
2. use of fertiliser
3. protecting crops from pests, disease & competition

Question 6

Why do livestock produce less food per unit area than crop plants?

Answer 6

Due to the energy loss between trophic levels (90% loss)

Question 7

What is the advantage of livestock production?

Answer 7

Not all land is suitable for growing crops

Question 8

State 2 reasons why light energy is absorbed by photosynthetic pigments.

Answer 8

Generate ATP and photolysis

Question 9

What are 2 possible consequences of light energy that is not absorbed?

Answer 9

Reflected or transmitted

Question 10

Name the 2 main pigments found inside chloroplasts.

Answer 10

Chlorophyll a and chlorophyll b

Question 11

Which 2 colours are mainly absorbed by chlorophyll a and b?

Answer 11

red and blue wavelengths

Question 12

Name the 2 pigments that make up the carotenoids.

Answer 12

carotene and xanthophyll

Question 13

What is the advantage to plants of having carotenoids?

Answer 13

They extend the range of wavelengths absorbed and pass the energy to chlorophyll for photosynthesis.

Question 14

What effect does absorbed light energy have on the pigment?

Answer 14

it excites electrons in the pigment molecule

Question 15

What happens to these excited electrons?

Answer 15

They pass through the electron transport chain

Question 16

Name the enzyme that produces ATP in the electron transport chain.

Answer 16

ATP synthase

Question 17

What does light energy do during photolysis?

Answer 17

Splits water into hydrogen and oxygen

Question 18

What is the fate of the oxygen?

Answer 18

It is evolved

Question 19

What is the name of the coenzyme that hydrogen ions are transferred to.

Answer 19

NADP

Question 20

What does NADP become when hydrogen ions have transferred to it?

Answer 20

NADPH

Question 21

What is another name for the carbon fixation stage of photosynthesis?

Answer 21

The Calvin cycle

Question 22

What gas is required for the Calvin cycle?

Answer 22

carbon dioxide

Question 23

Name the enzyme that fixes carbon dioxide and what is carbon dioxide attached to?

Answer 23

RuBisCO

ribulose biphosphate

Question 24

Name the molecule produced when carbon dioxide is fixed to ribulose biphosphate by RuBisCO.

Answer 24

3-phosphoglycerate (3PG)

Question 25

What is added to 3-phosphoglycerate during phosphorylation?

Answer 25

phosphate

Question 26

Where does the phosphate come from?

Answer 26

ATP

Question 27

Where does the ATP come from?

Answer 27

The first stage (the electron transport chain)

Question 28

Hydrogen ions are also added to 3-phosphoglycerate, where do they come from?

Answer 28

NADPH - from photolysis, splitting of water in the first stage

Question 29

What molecule is produced when hydrogen ions and phosphate molecules are added to 3-phosphoglycerate?

Answer 29

glyceraldehyde-3-phosphate (G3P)

Question 30

In the Calvin cycle, what 2 things does glyceraldehyde-3-phosphate become?

Answer 30

ribulose biphosphate | glucose

Question 31

State the 4 possible fates of glucose produced during photosynthesis.

Answer 31

1. respiratory substrate 2. starch for storage 3. cellulose - structural carbohydrate 4. passed to other biosynthetic pathways (to produce DNA, protein & fat)

Question 32

What does the absorption spectrum show?

Answer 32

It shows the wavelengths of light absorbed by the different pigments in the leaf.

Question 33

What does the action spectrum show?

Answer 33

How effective the different wavelengths are at photosynthesis.