Key area 3- Photosynthesis

Question 1

What are the 2 stages of photosynthesis?

Answer 1

Stage 1- light reactions
Stage 2- Carbon Fixation

Question 2

What is light reactions?

Answer 2

The light energy from the sun is trapped by chlorophyll in the chloroplasts and is converted into chemical energy which is used to generate the energy transfer molecule, ATP.
Water is split to produce hydrogen and oxygen. Oxygen diffuses from the cell.

Question 3

What is carbon fixation?

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 sugar e.g. glucose.

Question 4

What is the word equation for photosynthesis?

Answer 4

light energy
carbon dioxide + water ——————-> Sugar (glucose) +oxygen

Question 5

What is the glucose produced during photosynthesis used for?

Answer 5

The chemical energy in sugar is available for respiration or the sugar can be converted into other substances, such as starch (storage) and cellulose (structural).

Question 6

What are the limiting factors of photosynthesis

Answer 6

The limiting factors of photosynthesis are carbon dioxide concentration, light intensity and temperature.

Question 7

What happens if the limiting factors are in low supply or absent?

Answer 7

If any of the limiting factors of photosynthesis are in low supply or absent the rate of photosynthesis will slow down and so too will plant growth.