Key Area 3 - Photosynthesis

Question 1

What is photosynthesis?

Answer 1

A two-stage process that includes the light-reactions and carbon fixation

Question 2

What is the summary equation of photosynthesis?

Answer 2

carbon dioxide + water —light—chlorophyll—> glucose + oxygen

Question 3

What is chlorophyll?

Answer 3

A green substance within chloroplasts which captures the light energy that is used for photosynthesis and converts it into the chemical energy that is stored in carbohydrates

Question 4

What are the light reactions in the first stage of photosynthesis?

Answer 4

Light energy from the sun is trapped by chlorophyll in the chloroplasts and is converted into chemical energy that is used to make ATP. Some chemical energy is used to split water into oxygen and hydrogen. Oxygen diffuses from the cell

Question 5

What is carbon fixation (2nd stage of photosynthesis)?

Answer 5

A series of enzyme controlled reactions, which use hydrogen and ATP (produced by the light reactions) with carbon dioxide to produce glucose/sugar

Question 6

How can the chemical energy in the sugar be released?

Answer 6

By respiration. Or the sugar can be converted to other substances, such as starch (storage) and cellulose (structural)

Question 7

What factors can affect the rate of photosynthesis?

Answer 7

Light intensity, CO2 concentration and temperature

Question 8

If rate of photosynthesis is low, will it affect the rate of growth of the plant?

Answer 8

Yes

Question 9

What is a limiting factor of photosynthesis?

Answer 9

Something that is in short supply so is preventing the rate of photosynthesis from being any greater