3.3: Photosynthesis

Question 1

What is photosynthesis?

Answer 1

A two stage process in plants to make sugar from water and carbon dioxide, using light energy

Question 2

What is the basic word equation for photosynthesis?

COW SO

Answer 2

Carbon Dioxide + Water
LIGHT —–> ENERGY
Sugar + Oxygen

Question 3

What is the first stage of photosynthesis called?

Answer 3

Light Reactions

Question 4

Describe the first stage of photosynthesis

3

Answer 4

• Light energy from the sun is trapped by chlorophyll in the chloroplasts
• Some light energy is converted into chemical energy which is used to generate ATP
• The remaining light energy is used to split water into hydrogen and oxygen - oxygen diffuses from the cell

Question 5

What is the second stage of photosynthesis called?

Answer 5

Carbon Fixation

Question 6

Describe the second stage of photosynthesis

1

Answer 6

The ATP and hudrogen generated from light reactions and carbon dioxide from the air combine to be converted into sugar during a series of enzyme controlled reactions

Question 7

What are the 3 uses of sugar by plants?

Answer 7

• Respiration: used by plant in respiration to produce ATP
• Storage (starch): converted into starch for easier storage
• Structural (cellulose): converted into cellulose to make new cell walls as the plant grows

Question 8

What is a limiting factor?

Answer 8

A factor that prevents the reaction from going any faster unless adjusted

Question 9

What are the three limiting factors for photosynthesis?

TLC

Answer 9

• Temperature
• Light Intensity
• Carbon Dioxide Concentration