Key Area 3.3 - Photosynthesis

Question 1

Define the term photosynthesis

Answer 1

The chemical reaction that occurs in green plants

Question 2

Where does photosynthesis occur and what does it require?

Answer 2

Occurs in the leaves of plants

Requires light energy and green chloroplasts

Question 3

Give the word equation for photosynthesis

Answer 3

Carbon dioxide + water -> glucose + oxygen

Question 4

Name the two stages of photosynthesis

Answer 4

1. Light reactions

2. Carbon fixation

Question 5

Describe what happens during the first stage of photosynthesis

Answer 5

In the light reactions the LIGHT ENERGY from the sun is trapped by chlorophyll in the chloroplasts and is converted into CHEMICAL ENERGY which is used to generate ATP

In the light reactions water is split up to produce HYDROGEN and OXYGEN. Oxygen diffuses out of a cell

Question 6

Describe what happens during the second stage of photosynthesis

Answer 6

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

The chemical energy in sugar is available for RESPIRATION or the sugar can be converted into other substances, such as STARCH and CELLULOSE

Question 7

What is the chemical energy in sugar available for?

Answer 7

Respiration or the sugar can be converted into other substances such as starch and cellulose

Question 8

Identify the limiting factors for photosynthesis

Answer 8

Carbon dioxide concentration
Light intensity
Temperature

Question 9

What can the factors that affect starch production can be tested through?

Answer 9

Iodine testing in leaves

Question 10

Define what is meant by a limiting factor

Answer 10

A variable that, when in short supply, can limit the rate of a chemical reaction such as photosynthesis