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Question 1. Indicate which of the following statements are true.

a) DNA synthesis takes place during the mitotic (M) phase of the cell cycle.
True False

b) Analysis of chromosomes is carried out in the prophase stage of mitosis.
True False

c) Gametes contain the haploid number of chromosomes by the end of meiosis I.
True False

d) Oogenesis arrests in meiosis II until ovulation.
True False

e) Mitosis is the process of reduction division in gametogenesis.
True False

Question 2. Indicate which of the following statements are true.

a) Hydatidiform moles arise through dispermy.
True False

b) Crossing over routinely occurs between chromatids of homologous chromosomes in the prophase stage of meiosis I.
True False

c) Spermatids contain a single chromosome of each homologous pair.
True False

d) DNA replication is conservative.
True False

e) Centromeres of bivalent chromosomes separate in the anaphase stage of meiosis II.
True False

Question 3. Mitosis:

a) results in halving of the number of chromosomes in each daughter cell.
True False

b) usually lasts approximately 1-2 hours.
True False

c) can result in mosaicism due to non-disjunction.
True False

d) involves two cell divisions.
True False

e) occurs in all cells throughout life.
True False

Question 4. Indicate which of the following statements are true.

a) DNA transcription by RNA polymerase adds bases to mRNA in the 5' to 3' direction.
True False

b) RNA processing involves excision of exons from the heterogeneous nuclear mRNA.
True False

c) Intergenic DNA constitutes the majority of non-functional or 'junk' DNA.
True False

d) All of the genes in humans have been mapped and cloned.
True False

e) All genes in humans have non-coding or intronic sequences.
True False

Question 5. Indicate which of the following statements are true.

a) Somatic mutations cannot be transmitted to offspring.
True False

b) The majority of mutations arise through exposure to mutagenic agents.
True False

c) Mutations involving the insertion or deletion of 3 nucleotides alter the reading frame of a gene.
True False

d) Missense mutations in a gene always have an effect on the activity of the gene product.
True False

e) Nonsense mutations result in premature termination of translation.
True False

Question 6. Each of the following represents a balanced karyotype:

a) 46,XY,t(2;4)(q21;q21).
True False

b) 47,XX,+21.
True False

c) 46,X,i(Xq).
True False

d) 46,XY,inv(9)(p12q12).
True False

e) 46,XY/47,XXY.
True False

Question 7. In the process of sexual differentiation/determination:

a) an embryo with a 47,XXY karyotype develops into a male.
True False

b) SRY is usually involved in a recombinational event.
True False

c) an embryo with a 45,X karyotype will develop into a male or female depending upon whether an X or Y chromosome has been lost.
True False

d) inability to respond to testosterone in a 46,XY embryo results in the development of a female phenotype.
True False

e) one X chromosome in 46,XX embryos is completely inactivated.
True False

Question 8. For an autosomal recessive disorder in Hardy-Weinberg equilibrium with incidence of 1 in 6400:

a) the gene frequency equals 1 in 80.
True False

b) the carrier frequency equals approximately 1 in 40.
True False

c) the probability that the mother of an affected child is a carrier equals 1 in 2.
True False

d) the probability that the unaffected sibling of an affected child is a carrier equals 1 in 2.
True False

e) the probability that an unaffected sibling of an affected child will have an affected child with a healthy unrelated partner equals 1 in 240.
True False

Question 9. In a population showing Hardy-Weinberg equilibrium for a two allele (A and a) system, the proportion of AA homozygotes is found to be 0.36.

a) The gene frequency of A equals 0.06.
True False

b) The gene frequency of a equals 0.4.
True False

c) The proportion of aa homozygotes equals 0.16.
True False

d) The proportion of heterozygotes equals 0.24.
True False

e) If the total population size equals 10,000, the number of a genes in the population equals 8,000.
True False

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