PHS

Question 1

describe chemiosmosis

Answer 1

protons are pumped out of stroma using proton pumps and energy from electron transport chain. H+ ions from photolysis in the thylakoid space are also there. this maintains a conc gradient of H+ ion sin the thylakoid space and a low conc in the stroma. the only way that protons in the thylakoid space can move into the thylakoid is via a channel protein called ATP synthase. the H+ ions activate the enzyme and ATP is made from ADP and Pi.

Question 2

What can triose phosphate be used for

Answer 2

to regenerate RuBP so that the clavin cycle repeats itself. can be converted into a range of organic molecules such as starch.

Question 3

where does the light dependent stage of PHS occur

Answer 3

in the thylakoid membrane

Question 4

where does the light independent stage of PHS occur

Answer 4

In the stroma

Question 5

which biological molecule releases the most amount of energy when respired and why

Answer 5

This would be lipids because they have the most amount of hydrogen atoms.

Question 6

describe how grana is adapted for its function

Answer 6

it has a large surface area to volume ratio for maximum light absorption for light dependent stage. contain pigments/ photosystems. contain ETC and ATP synthase

Question 7

how will a leaf in the shade differ to a lead in light

Answer 7

leaf in the shade will have more photosystems/pigments to absorb a greater range of light, more chloroplasts and grana and a larger SA.

Question 8

how do heterotrophs rely on autotrophs

Answer 8

they require organic materials that are needed for making amino acids etc. they produce oxygen which is needed for respiration and make glucose during PHS which is also needed for PHS.

Question 9

what is a heterotroph

Answer 9

an animal that requires other organisms to acquire organic molecules etc …

Question 10

Discuss why measuring carbon dioxide uptake may or may not give a better indication of photosynthetic activity than measuring oxygen production

Answer 10

carbon dioxide is only used in the light dependent stage of PHS. Oxygen is only used in the light dependent stage of PHS. Both may be used in respiration therefore not all of the the carbon dioxide and oxygen will be used in PHS. this leads to an underestimation of the gas.