photosynthesis

Question 1

what is photosynthesis

Answer 1

1) anabolic process that uses sunlight energy to convert inorganic water and carbon dioxide into organic glucose.
2) light-dependent reactions and calvin cycle (light-independent reactions)
3) 6CO2 + 6H2O + sunlight + chlorophyll -> C6H12O6 + 6O2
4) leaves, stomata, chloroplasts involved

Question 2

what is the light dependent reaction (first stage)?

Answer 2

1) splits water into oxygen, w/ the help of sunlight energy captured by chlorophyll, to produce energy (ATP, NADPH) to drive the Calvin cycle
2) location: thylakoids, grana, granum
3) inputs: H2O + ADP + Pi + NADP+ + sunlight + chlorophyll
4) outputs: O2, ATP, NADPH

Question 3

what is the Calvin cycle/light independent reaction (second stage)?

Answer 3

1) NADPH and ATP produced from light-dependent reactions move into the stroma of the chloroplast. NADPH is split into NADP+ and H+, ATP is split into ADP and Pi, CO2 is combined with H+ released from NADPH to form glucose.
2) does not rely on light for energy

Question 4

what colours of light does chlorophyll pigment absorb the most energy from?

Answer 4

red and blue, the highest rate of photosynthesis occurs at these colours

Question 5

what are the structures of the chloroplast and their functions?

Answer 5

1) outer and inner membrane : control the movement of substances in and out of the chloroplast
2) thylakoid : flattened sac-like membrane structures. site of light-dependent reactions
3) granum : stacks of thylakoids
4) lamella : flat sheets of membrane that connect grana
5) stroma : the dense fluid between the inner membrane and thylakoid membranes

Question 6

what are the limiting factors of photosynthesis?

Answer 6

1) light intensity
2) temperature
enzymes at optimal temperatures, rate of photosynthesis increases. above optimal temperatures, enzymes denature and photosynthesis stops
3) CO2
4) water

Question 7

exam qn: if the leaves of a plant are covered in clear oil, explain the impact this would have on the photosynthetic rate. (2 marks)

Answer 7

if the leaves are covered in oil, the stomata will be blocked by the oil, inhibiting CO2 from diffusing through which reduces the photosynthesis rate.