2024 AQA A LEVEL BIOLOGY
COMMON AO1 EXAM QUESTIONS
WITH CORRECT ANSWERS
Explain why the sperms produced by a man are genetically different from
each other. - CORRECT-ANSWERSproduced by meiosis;
crossing over;
independent assortment of chromosomes;
Describe the structure of a cellulose molecule and explain how cellulose is
adapted for its function in cells. - CORRECT-ANSWERS1. made from β-
glucose;
2. joined by condensation/removing molecule of water/glycosidic bond;
3. 1 : 4 link specified or described;
4. "flipping over" of alternate molecules;
5. hydrogen bonds linking chains/long straight chains;
6. cellulose makes cell walls strong/cellulose fibres are strong;
7. can resist turgor pressure/osmotic pressure/pulling forces;
8. bond difficult to break;
9. resists digestion/action of microorganisms/enzymes;
Describe the behaviour of chromosomes during mitosis and explain how this
results in the production of two genetically identical cells. - CORRECT-
ANSWERSchromosomes shorten/thicken/supercoiling;
2 chromosomes (each) two identical chromatids/strands/copies
(due to replication)
3 chromosomes/chromatids move to equator/middle of the spindle/cell;
4 attach to individual spindle fibres;
5 spindle fibres contract / centromeres divide / repel;
6 (sister) chromatids/chromosomes (separate)
move to opposite poles/ends of the spindle;
7 each pole/end receives all genetic information/
identical copies of each chromosome;
8 nuclear envelope forms around each group of chromosomes/
chromatids/at each pole;
Explain how nitrate May cause the death of fish in fresh water - CORRECT-
ANSWERSLeaching occurs, nitrate ions washed into late
Bacteria such as algae
, Grow on top of the water
This reduces light penetration from the sun into the lake to the plants
Light needed for photosynthesis
Saprophytic bacteria aerobically respire so uses all the oxygen left in the
water
Lack of oxygen for the fish
Fish can't aerobically respire
Describe how to produce a mark release recapture method for fish -
CORRECT-ANSWERSCapture sample of fish using net
Mark the fish captured with a tag, no harm to the fish
Release those captured and let them redistribute back into population
2nd recapture, count all those marked
Equation:
N1 X N2
Divided by
N2
Glycolysis - CORRECT-ANSWERSAnaerobic process
Happens in cytoplasm (where enzyme is)
Uses 2 molecules of ATP (2x ADP produced)
To phosphorylate Glucose (more reactive)
Which is hydrolysed into 2x Triose phosphate
Which is oxidised to Pyruvate (2x Pyruvate)
Reduces NAD to NADH2
Describe how tissue fluid is formed and how it is returned to the circulatory
system. - CORRECT-ANSWERSFormation
1. High blood / hydrostatic pressure /
pressure filtration;
2. Forces water / fluid out;
3. Large proteins remain in capillary;
Return
4. Low water potential in capillary /
blood;
5. Due to (plasma) proteins;
6. Water enters capillary / blood;
7. (By) osmosis;
8. Correct reference to lymph;
Describe how carbon dioxide in the air outside a leaf reaches mesophyll cells
inside the leaf. - CORRECT-ANSWERS1. (Carbon dioxide enters) via stomata;
2. (Stomata opened by) guard cells;
3. Diffuses through air spaces;
4. Down diffusion gradient;
COMMON AO1 EXAM QUESTIONS
WITH CORRECT ANSWERS
Explain why the sperms produced by a man are genetically different from
each other. - CORRECT-ANSWERSproduced by meiosis;
crossing over;
independent assortment of chromosomes;
Describe the structure of a cellulose molecule and explain how cellulose is
adapted for its function in cells. - CORRECT-ANSWERS1. made from β-
glucose;
2. joined by condensation/removing molecule of water/glycosidic bond;
3. 1 : 4 link specified or described;
4. "flipping over" of alternate molecules;
5. hydrogen bonds linking chains/long straight chains;
6. cellulose makes cell walls strong/cellulose fibres are strong;
7. can resist turgor pressure/osmotic pressure/pulling forces;
8. bond difficult to break;
9. resists digestion/action of microorganisms/enzymes;
Describe the behaviour of chromosomes during mitosis and explain how this
results in the production of two genetically identical cells. - CORRECT-
ANSWERSchromosomes shorten/thicken/supercoiling;
2 chromosomes (each) two identical chromatids/strands/copies
(due to replication)
3 chromosomes/chromatids move to equator/middle of the spindle/cell;
4 attach to individual spindle fibres;
5 spindle fibres contract / centromeres divide / repel;
6 (sister) chromatids/chromosomes (separate)
move to opposite poles/ends of the spindle;
7 each pole/end receives all genetic information/
identical copies of each chromosome;
8 nuclear envelope forms around each group of chromosomes/
chromatids/at each pole;
Explain how nitrate May cause the death of fish in fresh water - CORRECT-
ANSWERSLeaching occurs, nitrate ions washed into late
Bacteria such as algae
, Grow on top of the water
This reduces light penetration from the sun into the lake to the plants
Light needed for photosynthesis
Saprophytic bacteria aerobically respire so uses all the oxygen left in the
water
Lack of oxygen for the fish
Fish can't aerobically respire
Describe how to produce a mark release recapture method for fish -
CORRECT-ANSWERSCapture sample of fish using net
Mark the fish captured with a tag, no harm to the fish
Release those captured and let them redistribute back into population
2nd recapture, count all those marked
Equation:
N1 X N2
Divided by
N2
Glycolysis - CORRECT-ANSWERSAnaerobic process
Happens in cytoplasm (where enzyme is)
Uses 2 molecules of ATP (2x ADP produced)
To phosphorylate Glucose (more reactive)
Which is hydrolysed into 2x Triose phosphate
Which is oxidised to Pyruvate (2x Pyruvate)
Reduces NAD to NADH2
Describe how tissue fluid is formed and how it is returned to the circulatory
system. - CORRECT-ANSWERSFormation
1. High blood / hydrostatic pressure /
pressure filtration;
2. Forces water / fluid out;
3. Large proteins remain in capillary;
Return
4. Low water potential in capillary /
blood;
5. Due to (plasma) proteins;
6. Water enters capillary / blood;
7. (By) osmosis;
8. Correct reference to lymph;
Describe how carbon dioxide in the air outside a leaf reaches mesophyll cells
inside the leaf. - CORRECT-ANSWERS1. (Carbon dioxide enters) via stomata;
2. (Stomata opened by) guard cells;
3. Diffuses through air spaces;
4. Down diffusion gradient;
