photosynthesis

Question 1

what is photosynthesis

Answer 1

All green plants get their energy from the sun. They do this through the process of photosynthesis.

Question 2

what is the photosynthesis word equation

Answer 2

co2 + water —> oxygen + glucose

Question 3

what are the raw materials, the requirements and products in the equation

Answer 3

raw materials - co2 and water
requirements - chlorophyll and light
products - oxygen and glucose

Question 4

where does photosynthesis occur

Answer 4

Photosynthesis happens in the leaves of green plants. This is due to a pigment called chlorophyll, found in
chloroplasts, which captures light energy. This energy is used to produce oxygen and glucose

Question 5

what are the two stages of photosynthesis

Answer 5

stage 1 - light reactions and stage 2 - carbon fixation

Question 6

what does stage one involve

Answer 6

Stage one involves the splitting of water and the release of oxygen.

Question 7

what does stage two involve

Answer 7

Stage two involves the combining of carbon dioxide and hydrogen to make sugar in the form of glucose.

Question 8

what happens in stage one - light reactions

Answer 8

The light energy from the sun is trapped by chlorophyll in the chloroplasts. Here, it is converted into chemical energy
which is used to generate ATP. This ATP is used to split water into hydrogen and oxygen. The splitting of water
generates more molecules of ATP.
Oxygen diffuses from the cell as it is not used by the plant. Hydrogen and ATP move onto stage two, carbon fixation.

Question 9

what happens in stage two - carbon fixation

Answer 9

Carbon fixation is a series of enzyme-controlled reactions which use hydrogen and ATP (produced by the light
reactions) with carbon dioxide to produce glucose in the form of sugar.

Question 10

The glucose produced by photosynthesis can be used for three things, what are they

Answer 10

• Storage: glucose can be converted to an insoluble carbohydrate called starch for storage
• Respiration: glucose can used as a substrate for respiration
• Structural: glucose can be converted to cellulose and used to build the cell wall

Question 11

how do you test a leaf for starch

Answer 11

Iodine is an orange chemical that turns blue/black in the presence of starch. Starch is a molecule that plants store their
glucose as. We can test if photosynthesis is happening in a plant, by testing for the presence of starch using iodine.

Question 12

A limiting factor slows down or stops the rate of a photosynthesis because it is in short supply. Three limiting factors of
photosynthesis are:

Answer 12

temperature
carbon dioxide concentration
light intensity