KA3.3 - Photosynthesis

Question 1

Photosynthesis is the process by which plants make their own … energy from … energy.

Answer 1

Chemical energy from light energy.

Question 2

List the layers of a leaf from top to bottom, starting with the upper epidermis?

Answer 2

Upper epidermis -> palisade mesophyll -> spongy mesophyll -> lower epidermis + guard cells

Question 3

State the parts of the leaf involved in photosynthesis?

Answer 3

• Palisade mesophyll
• spongy mesophyll
• guard cells.

Question 4

What is the word equation for photosynthesis?

Answer 4

Carbon dioxide + Water -> Sugar + Oxygen

Question 5

Photosynthesis occurs in two stages: … reaction stage and … stage

Answer 5

Light reaction stage and carbon fixation stage.

Question 6

Explain the steps in the light reaction stage of photosynthesis?

Answer 6

1. Light energy from the sun is trapped by chlorophyll in the chloroplasts and is converted into chemical energy which is used to generate ATP.
2. Water is split into hydrogen and oxygen.
3. Oxygen diffuses out of the cell.

Question 7

Explain the steps in the carbon fixation stage of photosynthesis?

Answer 7

It is a series of enzyme-controlled reactions, which use hydrogen and ATP (produced by the light reactions) with carbon dioxide to produce sugar.

Question 8

Sugar produced during photosynthesis can be used in …, stored as starch or converted into … to construct plant cell walls.

Answer 8

Respiration & Cellulose. Sugar produced during photosynthesis can be used in respiration, stored as starch or converted into cellulose to construct plant cell walls.

Question 9

What does the term limiting factor mean in the context of photosynthesis?

Answer 9

Anything that when it’s in short supply prevents photosynthesis from occurring at it’s maximum rate.

Question 10

The main limiting factors of photosynthesis are: …, … and …

Answer 10

• carbon dioxide concentration
• light intensity
• temperature.