age 1 of 49
AQA A LEVEL BIOLOGY PAPER 1 ACTUAL EXAM
2025/2026 || QUESTIONS WITH CORRECT DETAILED
ANSWERS || 100% GUARANTEED PASS <LATEST
UPDATE>
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
,age 2 of 49
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.
,age 3 of 49
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?
, age 4 of 49
.......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.
AQA A LEVEL BIOLOGY PAPER 1 ACTUAL EXAM
2025/2026 || QUESTIONS WITH CORRECT DETAILED
ANSWERS || 100% GUARANTEED PASS <LATEST
UPDATE>
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
,age 2 of 49
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.
,age 3 of 49
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?
, age 4 of 49
.......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.
