Practice Exam 3
VCE Biology Units 1 & 2 | Genetics, Heredity, DNA Replication & Cell Division
✎ Complete ALL questions on paper before opening the Model Answers lesson. No notes. Aim for 1 minute per mark.
MULTIPLE CHOICE
Question 1 (1 mark)
A homozygous dominant individual crossed with a homozygous recessive individual produces offspring that are all:
✎ Circle your answer
A) Homozygous dominant
B) Homozygous recessive
C) Heterozygous
D) 50% dominant, 50% recessive
Question 2 (1 mark)
In Mendel’s law of segregation, alleles separate during:
✎ Circle your answer
A) Fertilisation
B) DNA replication
C) Meiosis
D) Mitosis
Question 3 (1 mark)
A test cross involves crossing an unknown genotype with:
✎ Circle your answer
A) Another unknown individual
B) A homozygous dominant individual
C) A homozygous recessive individual
D) A heterozygous individual
Question 4 (1 mark)
The probability of a child having blood type O from two type A heterozygous parents (I^A i × I^A i) is:
✎ Circle your answer
A) 0
B) 1/4
C) 1/2
D) 3/4
Question 5 (1 mark)
Which of the following describes incomplete dominance?
✎ Circle your answer
A) Both alleles expressed simultaneously
B) Heterozygote shows intermediate phenotype
C) One allele completely masks the other
D) A trait determined by multiple genes
Question 6 (1 mark)
During DNA replication, the enzyme that adds new nucleotides to the growing strand is:
✎ Circle your answer
A) RNA polymerase
B) DNA ligase
C) DNA polymerase
D) Helicase
Question 7 (1 mark)
The term ‘phenotype’ refers to:
✎ Circle your answer
A) The genetic makeup of an organism
B) The observable characteristics of an organism
C) All possible alleles in a population
D) The sequence of bases in DNA
Question 8 (1 mark)
Mitosis results in:
✎ Circle your answer
A) Four haploid daughter cells
B) Two genetically identical diploid cells
C) Two cells with half the chromosome number
D) Cells with new combinations of alleles
Question 9 (1 mark)
Which base pairs with adenine in DNA?
✎ Circle your answer
A) Adenine
B) Guanine
C) Cytosine
D) Thymine
Question 10 (1 mark)
A woman is a carrier for a recessive X-linked condition. Her sons will:
✎ Circle your answer
A) All be carriers
B) All be unaffected
C) Have a 50% chance of being affected
D) All be affected
Question 11 (1 mark)
The process of crossing over during meiosis is significant because it:
✎ Circle your answer
A) Reduces chromosome number
B) Creates new combinations of alleles (genetic recombination)
C) Ensures exact chromosome copies
D) Separates homologous chromosomes
Question 12 (1 mark)
A gene with two alleles has the genotypic frequencies: 0.16 AA, 0.48 Aa, 0.36 aa. The frequency of the ‘a’ allele is:
✎ Circle your answer
A) 0.36
B) 0.48
C) 0.60
D) 0.84
Question 13 (1 mark)
Sex-linked traits in humans are carried on the:
✎ Circle your answer
A) Autosomes
B) Y chromosome only
C) X chromosome
D) Mitochondrial DNA only
Question 14 (1 mark)
The template strand of DNA is read in which direction by RNA polymerase?
✎ Circle your answer
A) 5′ to 3′
B) 3′ to 5′
C) Either direction
D) Only 5′ end
Question 15 (1 mark)
Meiosis II is similar to:
✎ Circle your answer
A) Meiosis I
B) Mitosis
C) DNA replication
D) Fertilisation
Question 16 (1 mark)
Which enzyme joins Okazaki fragments on the lagging strand?
✎ Circle your answer
A) DNA polymerase
B) Helicase
C) DNA ligase
D) Primase
Question 17 (1 mark)
A cross between two heterozygous individuals (Aa × Aa) produces offspring in a ratio of:
✎ Circle your answer
A) 1:1
B) 3:1 dominant:recessive
C) 1:2:1
D) 1:3
Question 18 (1 mark)
The term ‘locus’ refers to:
✎ Circle your answer
A) The specific position of a gene on a chromosome
B) The number of chromosomes in a cell
C) All alleles in a population
D) A type of mutation
Question 19 (1 mark)
Which stage of mitosis do chromosomes align at the cell equator?
✎ Circle your answer
A) Prophase
B) Anaphase
C) Metaphase
D) Telophase
Question 20 (1 mark)
Codominance is illustrated by:
✎ Circle your answer
A) Aa producing an intermediate phenotype
B) Both I^A and I^B alleles expressed in blood type AB
C) One allele masking another
D) X-linked inheritance
SHORT ANSWER
Question 21 (4 marks)
In guinea pigs, black coat (B) is dominant over white (b). A cross between two black guinea pigs produces 3 black and 1 white offspring. Determine the genotypes of the parents and show the cross.
✎ Write your answer on paper
Question 22 (4 marks)
Explain the process of semi-conservative DNA replication, including the roles of key enzymes.
✎ Write your answer on paper
Question 23 (4 marks)
A woman with normal colour vision whose father was colour blind marries a man with normal colour vision. What proportion of their sons will be colour blind? Show your working.
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Question 24 (4 marks)
Explain the difference between mitosis and meiosis in terms of purpose, number of cell divisions and genetic outcome.
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Question 25 (4 marks)
A gene for flower colour in snapdragons shows incomplete dominance. Red (R^R) × White (R^W) gives pink heterozygotes. Predict the offspring of a cross between two pink plants.
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Question 26 (4 marks)
Describe what occurs during the stages of meiosis I, including the significance of each stage.
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Question 27 (4 marks)
Explain the concept of multiple alleles using the ABO blood type system as an example.
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Question 28 (4 marks)
Explain how mutations can lead to changes in protein structure and function. Give one example of a beneficial and one harmful mutation.
✎ Write your answer on paper
EXTENDED RESPONSE
Extended Response 1
Question 29 (5 marks)
Extended Response 1 (a)
In Drosophila, body colour is autosomal: grey (G) dominant over black (g); wing type is X-linked: normal wing (W) dominant over vestigial wing (w).
A grey-bodied, normal-winged female (heterozygous for both traits) is crossed with a black-bodied, vestigial-winged male.
Write out the cross and determine the expected phenotype ratios among offspring.
✎ Write your answer on paper
Extended Response 1
Question 30 (3 marks)
Extended Response 1 (b)
Explain what is meant by ‘linkage’ and explain how it can affect expected Mendelian ratios.
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Extended Response 2: Cell Division
Question 31 (4 marks)
Extended Response 2: Cell Division (a)
Describe the role of cell cycle checkpoints in ensuring accurate cell division.
✎ Write your answer on paper
Extended Response 2: Cell Division
Question 32 (4 marks)
Extended Response 2: Cell Division (b)
Explain how mutations in cell cycle regulatory genes can lead to cancer.
✎ Write your answer on paper
✓ Finished? Open the next lesson – Model Answers – to mark your work.
