T6 - Photosynthesis

Question 1

What is photosynthesis

Answer 1

A chemical reaction that takes place inside photosynthetic organisms (e.g. plants, algae) converting light energy into chemical energy

Question 2

Word equation for photosynthesis

Answer 2

carbon dioxide + water > glucose + oxygen

Question 3

Why is photosynthesis important

Answer 3

It produces glucose which has a wide range of uses:
• Used in respiration to release energy
- Converted to starch and stored - broken down to glucose when the plant requires energy
- Used to make complex organic molecules which are used for growth making up an organism’s biomass (transferred through food chains)

Question 4

What type of reaction is photosynthesis?

Answer 4

Endothermic

Question 5

What is chlorophyll

Answer 5

A pigment found in chloroplasts that absorbs light

Question 6

Describe the two main stages of photosynthesis

Answer 6

1. Chlorophyll absorbs light energy which is used to split water into oxygen gas (waste product) and hydrogen ions
2. Carbon dioxide combines with hydrogen ions to form glucose

Question 7

What factors affect the rate of photosynthesis?

Answer 7

Temperature
Light intensity
CO2 concentration

Question 8

Explain how light intensity affects the rate of
photosynthesis

Answer 8

Rate of photosynthesis is directly proportional to
light intensity therefore as light intensity increases, the rate of photosynthesis increases.

Question 9

Why does the rate of photosynthesis eventually plateau even if light intensity continues to increase?

Answer 9

Another factor (temperature or CO, concentration) becomes limiting.