AQA A LEVEL BIOLOGY CELLS REVISION
PAPER 2023 WITH CORRECT QUESTIONS
AND ANSWERS
Structure of Nucleus (Correct Answers) 1. Nuclear envelope: double membrane
surrounding nucleus, outer membrane continuous with the (R)ER of the cell.
2. Nuclear pores: allow the passage of larger molecules, such as mRNA, out of the
nucleus.
3. Nucleoplasm: granular, jelly-like material making up the bulk of the nucleus.
4. Chromosomes: protein-bound, linear DNA.
5. Nucleolus: small spherical region(s) in nucleoplasm. Manufactures ribosomal RNA
and assembles ribosomes.
Function of the Nucleus (Correct Answers) 1. Controls cell's activities - produces mRNA
and tRNA - protein synthesis. Controls entry and exit of materials, and contains nuclear
reactions.
2. Retains genetic material in the form of DNA and chromosomes.
3. Manufactures ribosomal RNA and ribosomes.
Structure of Mitochondria (Correct Answers) 1. Double membrane surrounding
organelle - controls entry and exit of material.
2. Cristae - extensions of the inner membrane, providing a large surface area for the
attachment of enzymes and other proteins during respiration.
3. Matrix - makes up the remainder - contains proteins, lipids, ribosomes and DNA
(allows mitochondria to produce own proteins) and some respiratory enzymes.
Function of the Mitochondria (Correct Answers) 1. Sites of Krebs Cycle and oxidative
phosphorylation pathway in aerobic respiration - responsible for ATP production.
Structure of Chloroplasts (Correct Answers) Found in plants and algae.
,1. Chloroplast envelope - double plasma membrane, highly selective, surrounds the
organelle.
2. Grana - stacks of disc-shaped thylakoid membrane.
3. Thylakoids - contain chlorophyll used in photosynthesis, can be linked by lamellae to
other grana.
4. Stroma - fluid-filled matrix where Calvin Cycle takes place. Also contains starch
grains.
Functions of Chloroplasts (Correct Answers) Site of Photosynthesis:
LDR in thylakoid membranes.
LIR in stroma.
1. Granal membranes provide a large SA for LDR - photosystems, e- carriers and
enzymes etc.
2. Chloroplasts contain DNA and ribosomes - can quickly and easily manufacture some
of the proteins needed for photosynthesis.
Structure of Endoplasmic Reticulum (Correct Answers) 1. 3D system of sheet-like
membranes - continuous with the outer membrane of the nuclear double membrane.
2. Membrane contains a network of tubules and flattened sacs called cisternae.
3. RER - ribosomes on the outer surface of the membranes.
4. SER - lacks ribosomes on its surface and is often more tubular in its appearance.
Function of Endoplasmic Reticulum (Correct Answers) RER
1. Large SA for protein/glycoprotein synthesis.
2. Provides a pathway for material transport throughout the cell, especially for proteins.
SER
1. Synthesises, stores and transports lipids and carbohydrates.
Structure of Golgi Apparatus (Correct Answers) 1. Compact system of flattened sacs
and stacked membranes (cisternae).
, 2. Vesicles - modified proteins and lipids transported to cell membrane where they fuse
with it, and then egest contents to the outside.
Function of Golgi Apparatus (Correct Answers) 1. Form glycoproteins by adding carbs
to proteins.
2. Produce secretory enzymes, such as those secreted by the pancreas - apparatus is
developed in secretory cells, especially those in the small intestine.
3. Secrete carbs, such as cellulose for plant cell walls.
4. Transports, modifies and stores lipids.
5. Forms lysosomes.
Structure of Lysosomes (Correct Answers) Golgi vesicles with proteases, lipase and
lysozymes.
Functions of Lysosomes (Correct Answers) 1. Hydrolyse foreign material ingested by
phagocytes.
2. Exocytosis of enzymes to destroy extra-cellular material.
3. Apoptosis - programmed cell death.
Autolysis - breaking down cells after death.
4. Digest worn out organelles - can recycle chemicals.
Structure of Ribosomes (Correct Answers) 1. Small cytoplasmic granules found in all
cells, free-floating or associated with RER.
2. 80S - found in eukaryotic cells, slightly larger.
3. 70S - in prokaryotic cells, slightly smaller.
4. 2 Subunits - large and small - contain ribosomal RNA and proteins.
Functions of Ribosomes (Correct Answers) Carry out translation stage of protein
synthesis to produce polypeptides.
Structure of Cell Wall (Correct Answers) Found in plants, algae and fungi.
1. Cellulose microfibrils embedded in a matrix - contribute to overall cell wall strength
are considerably strong.
and other polysaccharides.
PAPER 2023 WITH CORRECT QUESTIONS
AND ANSWERS
Structure of Nucleus (Correct Answers) 1. Nuclear envelope: double membrane
surrounding nucleus, outer membrane continuous with the (R)ER of the cell.
2. Nuclear pores: allow the passage of larger molecules, such as mRNA, out of the
nucleus.
3. Nucleoplasm: granular, jelly-like material making up the bulk of the nucleus.
4. Chromosomes: protein-bound, linear DNA.
5. Nucleolus: small spherical region(s) in nucleoplasm. Manufactures ribosomal RNA
and assembles ribosomes.
Function of the Nucleus (Correct Answers) 1. Controls cell's activities - produces mRNA
and tRNA - protein synthesis. Controls entry and exit of materials, and contains nuclear
reactions.
2. Retains genetic material in the form of DNA and chromosomes.
3. Manufactures ribosomal RNA and ribosomes.
Structure of Mitochondria (Correct Answers) 1. Double membrane surrounding
organelle - controls entry and exit of material.
2. Cristae - extensions of the inner membrane, providing a large surface area for the
attachment of enzymes and other proteins during respiration.
3. Matrix - makes up the remainder - contains proteins, lipids, ribosomes and DNA
(allows mitochondria to produce own proteins) and some respiratory enzymes.
Function of the Mitochondria (Correct Answers) 1. Sites of Krebs Cycle and oxidative
phosphorylation pathway in aerobic respiration - responsible for ATP production.
Structure of Chloroplasts (Correct Answers) Found in plants and algae.
,1. Chloroplast envelope - double plasma membrane, highly selective, surrounds the
organelle.
2. Grana - stacks of disc-shaped thylakoid membrane.
3. Thylakoids - contain chlorophyll used in photosynthesis, can be linked by lamellae to
other grana.
4. Stroma - fluid-filled matrix where Calvin Cycle takes place. Also contains starch
grains.
Functions of Chloroplasts (Correct Answers) Site of Photosynthesis:
LDR in thylakoid membranes.
LIR in stroma.
1. Granal membranes provide a large SA for LDR - photosystems, e- carriers and
enzymes etc.
2. Chloroplasts contain DNA and ribosomes - can quickly and easily manufacture some
of the proteins needed for photosynthesis.
Structure of Endoplasmic Reticulum (Correct Answers) 1. 3D system of sheet-like
membranes - continuous with the outer membrane of the nuclear double membrane.
2. Membrane contains a network of tubules and flattened sacs called cisternae.
3. RER - ribosomes on the outer surface of the membranes.
4. SER - lacks ribosomes on its surface and is often more tubular in its appearance.
Function of Endoplasmic Reticulum (Correct Answers) RER
1. Large SA for protein/glycoprotein synthesis.
2. Provides a pathway for material transport throughout the cell, especially for proteins.
SER
1. Synthesises, stores and transports lipids and carbohydrates.
Structure of Golgi Apparatus (Correct Answers) 1. Compact system of flattened sacs
and stacked membranes (cisternae).
, 2. Vesicles - modified proteins and lipids transported to cell membrane where they fuse
with it, and then egest contents to the outside.
Function of Golgi Apparatus (Correct Answers) 1. Form glycoproteins by adding carbs
to proteins.
2. Produce secretory enzymes, such as those secreted by the pancreas - apparatus is
developed in secretory cells, especially those in the small intestine.
3. Secrete carbs, such as cellulose for plant cell walls.
4. Transports, modifies and stores lipids.
5. Forms lysosomes.
Structure of Lysosomes (Correct Answers) Golgi vesicles with proteases, lipase and
lysozymes.
Functions of Lysosomes (Correct Answers) 1. Hydrolyse foreign material ingested by
phagocytes.
2. Exocytosis of enzymes to destroy extra-cellular material.
3. Apoptosis - programmed cell death.
Autolysis - breaking down cells after death.
4. Digest worn out organelles - can recycle chemicals.
Structure of Ribosomes (Correct Answers) 1. Small cytoplasmic granules found in all
cells, free-floating or associated with RER.
2. 80S - found in eukaryotic cells, slightly larger.
3. 70S - in prokaryotic cells, slightly smaller.
4. 2 Subunits - large and small - contain ribosomal RNA and proteins.
Functions of Ribosomes (Correct Answers) Carry out translation stage of protein
synthesis to produce polypeptides.
Structure of Cell Wall (Correct Answers) Found in plants, algae and fungi.
1. Cellulose microfibrils embedded in a matrix - contribute to overall cell wall strength
are considerably strong.
and other polysaccharides.
