1
AQA A LEVEL BIOLOGY PAPER 2
QUESTION: why is converting sunlight energy into biomass in producers inefficient? - ANSWER-some
light isn't the correct wavelength to be absorbed
some light doesnt hit chloroplast
some light is converted into heat energy
some light energy is reflected
QUESTION: describe and explain the steps in the light independent reaction pf photosynthesis. -
ANSWER-1. CO2 diffuses into stroma and combines with ribulose bisphosphate (RuBP) using the enzyme
rubisco.
2. this forms an unstable 6 carbon molecule, which splits into 2 3 carbon molecules, glyercate-3-
phosphate (G3P) .
3. G3P is reduced by NADPH to triose-phosphate (TP), which is aided by ATP for energy.
4. TP can be converted into useful organic substances.
5. TP can also be reformed into RuBP using ATP.
QUESTION: describe glycolysis in respiration. give net formation. - ANSWER-1. glucose is converted into
phosphorylated glucose by 2ATP. this makes it very reactive, so it splits into 2 triose phosphate (TP).
2. 2TP is then oxidised by 2NAD and 4 ATP is formed to form pyruvate.
3. NET: 2ATP, 2Pyruvate, 2NADH, 2H+
QUESTION: describe links reaction in respiration. give net formation. - ANSWER-1. pyruvate diffuses into
the matrix of mitochondria.
, 2
2. pyruvate is oxidised by NAD. CO2 is lost. this forms acetate.
3. acetate and co-enzyme A combine to form acetyl co-enzyme A.
4. NET: CO2, reduced NAD, acetyl co-enzyme A
QUESTION; describe and explain the steps in the light dependent reaction of photosynthesis - ANSWER-
1. photoionisation: light reaches chlorophyll in PSII, which is absorbed by an electron, which becomes
excited and moves to a higher energy level.
2. the electron passes to a carrier protein in the thylakoid membrane, and is passed down a series of
carrier molecules called an electron transfer chain.
3. as the electron moves down, energy is lost from the electron and is released as ATP.
4. the loss of electron from PSII is 'refilled' by an electron produced by photolysis, which also produces
hydrogen and oxygen.
5. the lost electron reaches PSI, which absorbs light energy and boosts another electron to a higher
energy level (excitation).
6. this electron also goes down an electron transport chain.
7. this reaches the final electron acceptor which is a proton. they combine to form H and reduce NADP
to NADPH.
QUESTION: describe oxidative phosphorylation in respiration. - ANSWER-1. reduced coenzyme passes
its H to a carrier protein in the ETC. this splits into a proton and electron.
2. the protons pass through the space between inner and outer mitochondrial membrane.
3. electrons pass through proteins on ETC.
4. protons return back via ATP synthase in the membrane, producing ATP.
, 3
5. the protons and electrons recombine to form H, which combines with O to form water.
6. oxygen is the last electron acceptor in the ETC.
QUESTION; describe and explain the steps in the light dependent reaction of photosynthesis - ANSWER-
1. photoionisation: light reaches chlorophyll in PSII, which is absorbed by an electron, which becomes
excited and moves to a higher energy level.
2. the electron passes to a carrier protein in the thylakoid membrane, and is passed down a series of
carrier molecules called an electron transfer chain.
3. as the electron moves down, energy is lost from the electron and is released as ATP.
4. the loss of electron from PSII is 'refilled' by an electron produced by photolysis, which also produces
hydrogen and oxygen.
5. the lost electron reaches PSI, which absorbs light energy and boosts another electron to a higher
energy level (excitation).
6. this electron also goes down an electron transport chain.
7. this reaches the final electron acceptor which is a proton. they combine to form H and reduce NADP
to NADPH.
QUESTION: define biomass - ANSWER-the total mass of organisms in a given area
QUESTION: what is the 'gross primary production' - ANSWER-the chemical energy stored in a plants
biomass
AQA A LEVEL BIOLOGY PAPER 2
QUESTION: why is converting sunlight energy into biomass in producers inefficient? - ANSWER-some
light isn't the correct wavelength to be absorbed
some light doesnt hit chloroplast
some light is converted into heat energy
some light energy is reflected
QUESTION: describe and explain the steps in the light independent reaction pf photosynthesis. -
ANSWER-1. CO2 diffuses into stroma and combines with ribulose bisphosphate (RuBP) using the enzyme
rubisco.
2. this forms an unstable 6 carbon molecule, which splits into 2 3 carbon molecules, glyercate-3-
phosphate (G3P) .
3. G3P is reduced by NADPH to triose-phosphate (TP), which is aided by ATP for energy.
4. TP can be converted into useful organic substances.
5. TP can also be reformed into RuBP using ATP.
QUESTION: describe glycolysis in respiration. give net formation. - ANSWER-1. glucose is converted into
phosphorylated glucose by 2ATP. this makes it very reactive, so it splits into 2 triose phosphate (TP).
2. 2TP is then oxidised by 2NAD and 4 ATP is formed to form pyruvate.
3. NET: 2ATP, 2Pyruvate, 2NADH, 2H+
QUESTION: describe links reaction in respiration. give net formation. - ANSWER-1. pyruvate diffuses into
the matrix of mitochondria.
, 2
2. pyruvate is oxidised by NAD. CO2 is lost. this forms acetate.
3. acetate and co-enzyme A combine to form acetyl co-enzyme A.
4. NET: CO2, reduced NAD, acetyl co-enzyme A
QUESTION; describe and explain the steps in the light dependent reaction of photosynthesis - ANSWER-
1. photoionisation: light reaches chlorophyll in PSII, which is absorbed by an electron, which becomes
excited and moves to a higher energy level.
2. the electron passes to a carrier protein in the thylakoid membrane, and is passed down a series of
carrier molecules called an electron transfer chain.
3. as the electron moves down, energy is lost from the electron and is released as ATP.
4. the loss of electron from PSII is 'refilled' by an electron produced by photolysis, which also produces
hydrogen and oxygen.
5. the lost electron reaches PSI, which absorbs light energy and boosts another electron to a higher
energy level (excitation).
6. this electron also goes down an electron transport chain.
7. this reaches the final electron acceptor which is a proton. they combine to form H and reduce NADP
to NADPH.
QUESTION: describe oxidative phosphorylation in respiration. - ANSWER-1. reduced coenzyme passes
its H to a carrier protein in the ETC. this splits into a proton and electron.
2. the protons pass through the space between inner and outer mitochondrial membrane.
3. electrons pass through proteins on ETC.
4. protons return back via ATP synthase in the membrane, producing ATP.
, 3
5. the protons and electrons recombine to form H, which combines with O to form water.
6. oxygen is the last electron acceptor in the ETC.
QUESTION; describe and explain the steps in the light dependent reaction of photosynthesis - ANSWER-
1. photoionisation: light reaches chlorophyll in PSII, which is absorbed by an electron, which becomes
excited and moves to a higher energy level.
2. the electron passes to a carrier protein in the thylakoid membrane, and is passed down a series of
carrier molecules called an electron transfer chain.
3. as the electron moves down, energy is lost from the electron and is released as ATP.
4. the loss of electron from PSII is 'refilled' by an electron produced by photolysis, which also produces
hydrogen and oxygen.
5. the lost electron reaches PSI, which absorbs light energy and boosts another electron to a higher
energy level (excitation).
6. this electron also goes down an electron transport chain.
7. this reaches the final electron acceptor which is a proton. they combine to form H and reduce NADP
to NADPH.
QUESTION: define biomass - ANSWER-the total mass of organisms in a given area
QUESTION: what is the 'gross primary production' - ANSWER-the chemical energy stored in a plants
biomass
