Photosynthesis

Question 1

Where does photosynthesis take place?

Answer 1

Photosynthesis takes place in chloroplasts.

Question 2

Why are green plants called producers?

Answer 2

Producers are green plants that make food by photosynthesis. Green plants are called producers because they can “fix” carbon dioxide into food (glucose) using light energy from the sun.

Question 3

Describe where chlorophyll can be found and and its function.

Answer 3

Chloroplasts contain green pigment called chlorophyll which absorbs light energy for the photosynthesis chemical reactions to take place.

Question 4

What is the summary words equation for photosynthesis?

Answer 4

Raw materials Requirements Products
Light
carbon dioxide + water——>glucose + oxygen
chlorophyll

Question 5

What are the two stages of photosynthesis called?

Answer 5

Photosynthesis includes two pathways:

Light reaction and carbon fixation

Question 6

Describe what happens in the first stage of photosynthesis?

Answer 6

The first stage of photosynthesis is called the light reaction.
During 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 the energy transfer molecule, ATP.
Water is split to produce hydrogen and oxygen.
Oxygen diffuses from the cell.

Question 7

Describe what happens during the second stage of photosynthesis.

Answer 7

The second stage of photosynthesis is called carbon fixation.
Carbon fixation, uses hydrogen and ATP from the light reactions to convert carbon dioxide from the air into glucose (sugar).
The carbon fixation reactions are catalysed by enzymes: this means that the rate of carbon fixation reactions are affected by temperature.

Question 8

What is the fate of glucose which is produced by photosynthesis?

Answer 8

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 9

What are the factors which can affect the rate of photosythesis?

Answer 9

Environmental factors that can affect the rate of photosynthesis are:
Light intensity
Carbon dioxide concentration
Temperature

Question 10

What is a limiting factor?

Answer 10

A limiting factor is a factor that holds up a process when it (the factor) is in short supply.