aqa biology paper 2 comprehensive
review study guide tested questions
100
⩥ 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.
⩥ 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+
⩥ describe links reaction in respiration. give net formation. Answer:
1. pyruvate diffuses into the matrix of mitochondria.
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
⩥ describe krebs cycle in respiration. give net formation. Answer: 1.
acetyl co-enzyme A combines with 4 carbon molecule (oxaloacetate)
to form 6 carbon citric acid.
2. CO2 is lost (decarboxylation), molecule is oxidised by NAD and
ATP is produce. this forms 5 carbon compound.
3. it is oxidised by 2NADH and FAD, and is decarboxylated.
4. this forms 4 carbon molecule again.
⩥ 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.
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.
⩥ define biomass Answer: the total mass of organisms in a given area
, ⩥ what is the 'gross primary production' Answer: the chemical energy
stored in a plants biomass
⩥ what is the 'net primary production' Answer: the chemical energy
stores in a plants biomass after respiratory losses have been
considered. this energy is available to consumers.
⩥ how can you calculate the net primary production? Answer: NPP =
GPP - R
⩥ 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
⩥ describe the nitrogen cycle. Answer: fixation:
atmospheric nitrogen can be fixed by rhizbium bacteria.
if struck by lightning, it becomes reactive and combines with oxygen
to form NO.
ammonification:
saprobionts feed on organic matter and release ammonia, which then
forms ammonium ions in the soil.
review study guide tested questions
100
⩥ 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.
⩥ 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+
⩥ describe links reaction in respiration. give net formation. Answer:
1. pyruvate diffuses into the matrix of mitochondria.
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
⩥ describe krebs cycle in respiration. give net formation. Answer: 1.
acetyl co-enzyme A combines with 4 carbon molecule (oxaloacetate)
to form 6 carbon citric acid.
2. CO2 is lost (decarboxylation), molecule is oxidised by NAD and
ATP is produce. this forms 5 carbon compound.
3. it is oxidised by 2NADH and FAD, and is decarboxylated.
4. this forms 4 carbon molecule again.
⩥ 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.
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.
⩥ define biomass Answer: the total mass of organisms in a given area
, ⩥ what is the 'gross primary production' Answer: the chemical energy
stored in a plants biomass
⩥ what is the 'net primary production' Answer: the chemical energy
stores in a plants biomass after respiratory losses have been
considered. this energy is available to consumers.
⩥ how can you calculate the net primary production? Answer: NPP =
GPP - R
⩥ 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
⩥ describe the nitrogen cycle. Answer: fixation:
atmospheric nitrogen can be fixed by rhizbium bacteria.
if struck by lightning, it becomes reactive and combines with oxygen
to form NO.
ammonification:
saprobionts feed on organic matter and release ammonia, which then
forms ammonium ions in the soil.
