3.3 PHOTOSYNTHESIS

Question 1

The 2stages of photosynthesis

Answer 1

Stage one - light reactions

Stage two - carbon fixiation

Question 2

What happens in the first stage of photosynthesis

Answer 2

The light energy from the sun is trapped by chlorophyll in the chloroplasts. Here, it is converted into chemical energy
which is used to generate ATP. This ATP is used to split water into hydrogen and oxygen. The splitting of water
generates more molecules of ATP.

Question 3

What happens in stage 2 of photosynthesis

Answer 3

Carbon fixation is a series of enzyme-controlled reactions which use hydrogen and ATP (produced by the light
reactions) with carbon dioxide to produce glucose in the form of sugar.

Question 4

What is the glucose made in photosynthesis used for

Answer 4

Storage: glucose can be converted to an insoluble carbohydrate called starch for storage

• Respiration: glucose can used as a substrate for respiration
• Structural: glucose can be converted to cellulose and used to build the cell wall

Question 5

What limits the rate of photosynthesis and can analyse limiting factors graphs

Answer 5

Temperature

• Carbon dioxide concentration
• Light intensity