Photosynthesis

Question 1

What is photosynthesis controlled by?

Answer 1

Enzymes

Question 2

What are the raw materials for photosynthesis?

Answer 2

Carbon dioxide + water

Question 3

What are the essential requirements for photosynthesis?

Answer 3

Light energy + chlorophyll + enzymes

Question 4

What are the products of photosynthesis?

Answer 4

Glucose + oxygen

Question 5

Where does photosynthesis take place?

Answer 5

Chloroplast

Question 6

Chloroplast contains green pigment all called what?

Answer 6

Chlorophyll

Question 7

What is the first stage of photosynthesis?

Answer 7

The light reactions stage

Question 8

What is the second stage of photosynthesis?

Answer 8

Carbon fixation

Question 9

What happens during the light reactions stage?

Answer 9

• the light reactions stage takes place in the chloroplast. Light energy from the sun is trapped by chlorophyll in the chloroplasts and converted into chemical energy.
• the chemical energy is used to soil water molecules in to hydrogen and oxygen.
• excess oxygen diffuses from the cell and is released into the air as a waste product.
• the hydrogen is carried to the next stage of photosynthesis.
• some of the light energy is used to make ATP.

Question 10

What happens during the carbon fixation stage?

Answer 10

• takes place in the chloroplast.
• hydrogen from the light reactions stage is combined with carbon dioxide. This produces the sugar glucose.
• the energy from this process comes from ATP also gained from the light reactions stage.
• the reaction is controlled by enzymes and is therefore temperature sensitive.

Question 11

What are the 3 possible dates of glucose?

Answer 11

1. Glucose can be used in the process of respiration to release energy for the plant to survive.
2. Glucose can be converted into starch and stored. The starch can be changed back into glucose is the plant needs energy.
3. Glucose can also be converted into cellulose and used to make cell walls.

Question 12

What are the 3 limiting factors that reduce a plants rate of photosynthesis?

Answer 12

1. Temperature
2. Light intensity
3. Carbon dioxide concentration

Question 13

What 3 points happen when investigating the effects of light intensity on the rate of photosynthesis?

Answer 13

• temperature and carbon dioxide concentration are constant.
• as light intensity increases, the rate of photosynthesis increases.
• further increases in light causes no further increase in the rate of photosynthesis since the light intensity is no longer a limiting factor.

Question 14

What 3 points happen when investigating the effects of CO2 concentration on the rate of photosynthesis?

Answer 14

• temperature and light intensity are constant.
• as CO2 concentration increases, the rate of photosynthesis increases.
• further increase in CO2 concentration chaises no further increase in the rate of photosynthesis since the rate is limited by a shortage of some other factors.

Question 15

What 4 points happen when investigating the effects of temperature on the rate of photosynthesis?

Answer 15

• CO2 and light intensity are constant.
• as temperature increases rate of photosynthesis increases due to increasing enzyme activity.
• rate of photosynthesis at a maximum as enzymes are working at their optimum temperature and therefore its fastest rate.
• as temperature increases further, rate of photosynthesis decreases. This is due to enzymes becoming denatured and eventually no longer catalysing reactions.