Photosynthesis

Question 1

What are the three stages of C3 Photosynthesis (The Calvin cycle)

Answer 1

1. Carbon fixation
2. Reduction
3. Regeneration

Question 2

What happens in the Carbon Fixation stage of C3 photosynthesis?

Answer 2

Co2 combines with ribulose biphosphate (RuBP), catalysed by the enzyme rubisco

Question 3

What happens in the Reduction stage of C3 photosynthesis?

Answer 3

NADPH and ATP are used to turn molecules into 3-carbon sugar called G3P

Question 4

What happens in the Regeneration stage of C3 photosynthesis?

Answer 4

1. Some sugars go off to make glucose
2. Others regenerate to make ribulose biphosphate (RuBP) to start cycle again

Question 5

Where does C3 photosynthesis occur?

Answer 5

C3 photosynthesis occurs in the chloroplast

Question 6

What happens in the mesophyll cell in C4 photosynthesis?

Answer 6

1. CO2 is fixed in the mesophyll cell to form 4-carbon organic acid (oxaloacetate)
2. Carried out by PEP enzyme
3. Oxaloacetate is then converted to malate which is then transported to the bundle-sheath cells

Question 7

What happens in the bundle sheath cells in C4 photosynthesis?

Answer 7

1. Malate breaks down releasing a CO2 molecule
2. CO2 is then used in The Calvin Cycle.

Question 8

What type of plants use CAM photosynthesis? How do they use it differently?

Answer 8

1. Plants adapted to dry environments e.g cacti and pineapples
2. They use it by avoiding photorespiration and do photosynthetic processes over time

Question 9

What happens during the night in CAM photosynthesis plants?

Answer 9

1. At night CAM plants open their stomata, to diffuse CO2 into their leaves.
2. CO2 is fixed into oxaloacetate by PEP, then converted to malate or another organic acid
3. Organic acid is stored inside vacuoles until next day.

Question 10

What happens during the day in CAM photosynthesis plants?

Answer 10

1. Organic acids are broken down into CO2 to enter The Calvin Cycle