Biology Edexcel A Level (TOPIC
3) exam questions with
answers 2023
3.10: Draw a flowchart that shows how different organelles and nucleus involved
in the process of protein production and trafficking in a cell. - Answer 1.
transcription of DNA to mRNA
2. mRNA leaves nucleus
3. protein made on ribosomes enter RER
4. protein moves through the ER assuming 3D shape (folding)
5. vesicles pinched off the RER contain the protein
6. vesicles from RER fuse to form the flattened sacs of Golgi Apparatus
7. proteins are modified within the Golgi Apparatus
8. vesicles pinched off the GA contained modified protein
,9. vesicles fuse with GA cell surface membrane and releases it by exocytosis
3.11: Describe and explain the role of the RER and golgi apparatus in protein
production and modification. - Answer RER- produces proteins in ribosomes and
folds them assuming 3D shape
Golgi Apparatus- modified within here, e.g.: add glycoprotein
3.12: Draw an ovum (egg cell), label the structures and describe their functions. -
Answer Haploid Nucleus: contains genetic code
Mitochondria: used for energy
Cortical Granules: involved in cortical reaction to prevent polyspermy
Lipid Droplets: used as an energy store
Cell Surface Membrane: controls what enters and exits the cell
Jelly Coat: prevent polyspermy/protection
1.13: Explain why an ovum needs to be large. - Answer The ovum needs to be
large relative to the sperm so it can be more easily found and act as a bigger
target.
3.14: Draw a sperm cell, label the structures and describe their function. - Answer
Acrosome: takes part in acrosome reaction to digest zona pellucida and follicle
cells
Haploid Nucleus: contains genetic code
Middle Piece: contains mitochondria
Flagellum: make sperm motle
Mitochondria: energy store
, 3.15: Draw a flow chart that shows how a sperm reaches an ovum and fertilisation
is achieved (including the stages in the acrosome reaction, the cortical reaction
and fertilisation of the nuclei). - Answer 1. sperm reaches ovum
2. acrosome reaction is triggered by chemicals from the ovum (follicle cell)
3. acrosome swells and fuses with cell surface membrane of sperm
4. digestive enzymes released
5. enzymes digest follicle cells and jelly coat
6. sperm moves to egg cell surface membrane and fuses
7. sperm nucleus and egg nuclei fuse after sperm nuclei moves through egg cell
surface membrane
8. cortical grannuels release enzymes and thicken jelly coat
3.16: Define the terms chromosome, homologous pair, locus, gamete, haploid,
diploid. - Answer Chromosome- DNA molecule, histone proteins
Homologous Pair- Pair of chromosomes that have same genes
Locus: Location (of gene on chromosomes)
Gamete: Sex cell, produced in mitosis
Haploid: Half number of chromosomes
Diploid: Regular number of chromosomes
3.17: Explain the terms linkage of genes and sex linkage. - Answer Genetic
Linkage: is the tendency of alleles that are located close together on a
chromosome to be inherited together during meiosis phase of sexual
reproduction
3) exam questions with
answers 2023
3.10: Draw a flowchart that shows how different organelles and nucleus involved
in the process of protein production and trafficking in a cell. - Answer 1.
transcription of DNA to mRNA
2. mRNA leaves nucleus
3. protein made on ribosomes enter RER
4. protein moves through the ER assuming 3D shape (folding)
5. vesicles pinched off the RER contain the protein
6. vesicles from RER fuse to form the flattened sacs of Golgi Apparatus
7. proteins are modified within the Golgi Apparatus
8. vesicles pinched off the GA contained modified protein
,9. vesicles fuse with GA cell surface membrane and releases it by exocytosis
3.11: Describe and explain the role of the RER and golgi apparatus in protein
production and modification. - Answer RER- produces proteins in ribosomes and
folds them assuming 3D shape
Golgi Apparatus- modified within here, e.g.: add glycoprotein
3.12: Draw an ovum (egg cell), label the structures and describe their functions. -
Answer Haploid Nucleus: contains genetic code
Mitochondria: used for energy
Cortical Granules: involved in cortical reaction to prevent polyspermy
Lipid Droplets: used as an energy store
Cell Surface Membrane: controls what enters and exits the cell
Jelly Coat: prevent polyspermy/protection
1.13: Explain why an ovum needs to be large. - Answer The ovum needs to be
large relative to the sperm so it can be more easily found and act as a bigger
target.
3.14: Draw a sperm cell, label the structures and describe their function. - Answer
Acrosome: takes part in acrosome reaction to digest zona pellucida and follicle
cells
Haploid Nucleus: contains genetic code
Middle Piece: contains mitochondria
Flagellum: make sperm motle
Mitochondria: energy store
, 3.15: Draw a flow chart that shows how a sperm reaches an ovum and fertilisation
is achieved (including the stages in the acrosome reaction, the cortical reaction
and fertilisation of the nuclei). - Answer 1. sperm reaches ovum
2. acrosome reaction is triggered by chemicals from the ovum (follicle cell)
3. acrosome swells and fuses with cell surface membrane of sperm
4. digestive enzymes released
5. enzymes digest follicle cells and jelly coat
6. sperm moves to egg cell surface membrane and fuses
7. sperm nucleus and egg nuclei fuse after sperm nuclei moves through egg cell
surface membrane
8. cortical grannuels release enzymes and thicken jelly coat
3.16: Define the terms chromosome, homologous pair, locus, gamete, haploid,
diploid. - Answer Chromosome- DNA molecule, histone proteins
Homologous Pair- Pair of chromosomes that have same genes
Locus: Location (of gene on chromosomes)
Gamete: Sex cell, produced in mitosis
Haploid: Half number of chromosomes
Diploid: Regular number of chromosomes
3.17: Explain the terms linkage of genes and sex linkage. - Answer Genetic
Linkage: is the tendency of alleles that are located close together on a
chromosome to be inherited together during meiosis phase of sexual
reproduction
