AQA biology a-level paper 2 Exam with | | | | | | |
precise detailed solutions | |
describe and explain the steps in the light dependent reaction of photosynthesis
| | | | | | | | | | | |
- Correct 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.
| | | | | |
describe and explain the steps in the light independent reaction pf
| | | | | | | | | | |
photosynthesis. - Correct 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. - Correct 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. - Correct 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. - Correct 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. - Correct 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 - Correct answer ✔the total mass of organisms in a given area
| | | | | | | | | | | | |
what is the 'gross primary production' - Correct answer ✔the chemical energy
| | | | | | | | | | | |
stored in a plants biomass | | | |
what is the 'net primary production' - Correct 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? - Correct answer ✔NPP =
| | | | | | | | | | | | |
GPP - R | |
why is converting sunlight energy into biomass in producers inefficient? -
| | | | | | | | | | |
Correct answer ✔some light isn't the correct wavelength to be absorbed
| | | | | | | | | |
some light doesnt hit chloroplast
| | | |
precise detailed solutions | |
describe and explain the steps in the light dependent reaction of photosynthesis
| | | | | | | | | | | |
- Correct 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.
| | | | | |
describe and explain the steps in the light independent reaction pf
| | | | | | | | | | |
photosynthesis. - Correct 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. - Correct 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. - Correct 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. - Correct 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. - Correct 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 - Correct answer ✔the total mass of organisms in a given area
| | | | | | | | | | | | |
what is the 'gross primary production' - Correct answer ✔the chemical energy
| | | | | | | | | | | |
stored in a plants biomass | | | |
what is the 'net primary production' - Correct 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? - Correct answer ✔NPP =
| | | | | | | | | | | | |
GPP - R | |
why is converting sunlight energy into biomass in producers inefficient? -
| | | | | | | | | | |
Correct answer ✔some light isn't the correct wavelength to be absorbed
| | | | | | | | | |
some light doesnt hit chloroplast
| | | |
