BIO 207S (2004)
GENETICS
Due Friday, Feb 11, by 4:55 p.m.
Place in box labelled BIO 207 Problem Sets (inside Room 3030)
PROBLEM SET #2
Multiple Choice questions: Circle the correct answer.
1) A process that occurs in meiosis but not mitosis is
a) pairing of homologs.
b) chromatid formation.
c) cell division.
d) separation of homologous centromeres to opposite poles.
e) chromosome condensation (shortening).
2) In a plant of 2n = 24, what is the total number of chromatids present during prophase
I of meiosis?
a) 6
b) 12
c) 24
d) 48
e) 96
3) Ploidy is
a) the number of genes in a cell.
b) the number of chromosomes in a cell.
c) the amount of DNA in a cell.
d) the number of chromosomes in a chromosome set.
e) the number of chromosome sets.
4) The ‘pulling apart’ stages of both mitosis and meiosis are called
a) prophase.
b) metaphase.
c) anaphase.
d) telophase.
e) interphase.
5) A characteristic of homologous chromosomes is that
a) they carry alleles for the same genes in the same relative positions.
b) they regularly exchange parts by crossing over at meiosis.
c) in a diploid cell in interphase they are found in pairs but they do not physically
pair.
d) they physically pair at meiosis.
e) a and b.
f) a, b, c.
g) b, c, d.
h) b, c.
i) All of the above.
6) Which diagram most accurately shows the arrangement of homologous chromosomes
during the metaphase of mitosis?
a.
b.
d.
c.
e.
7) In a diploid organism 2n = 6, and there are two long, two intermediate, and two short
chromosomes. What is the most accurate representation of a gamete resulting from
meiosis in this organism?
a)
b)
c)
d)
e)
8) Circle the Source or Sources of Normal Genetic Variation found below:
a) Mutation
b) DNA Synthesis
c) Random Fertilization
d) DNA Repair
e) Independent Assortment of Chromosomes
f) Recombination (crossing-over)
g) Artificial selection.
9) In a dihybrid the genes are located on different chromosomes. Which of the
following diagrams does not represent a stage of meiosis in this organism?
a)
\
b)
c)
d)
e)
10) Normal diploid somatic (body) cells of the mosquito, Culex pipiens, contain six
chromosomes. Assign the symbols Am Ap, BmBp, and CmCp to the three homologous
chromosomal pairs. The “m” superscript indicates that the homologue is maternally
derived, while the “p” indicates a paternally derived homologue. Assume that in the
genus Culex, the sex chromosoomes are morphologically identical.
a) For each of the cell types given below, draw and label (with reference to the
symbols defined above) an expected chromosomal configuration.
Mitotic Metaphase
Metaphase of Meiosis I
Metaphase of Meiosis II
b) The stage at which “sister chromatids go to opposite poles” immediately follows
which of the above stages?
c) Assuming that all nuclear DNA is restricted to chromosomes and that the amount
of nuclear DNA essentially doubles during the S phase of interphase, how much
nuclear DNA would be present in each cell listed above? Note: assume that the
G1 nucleus of a mosquito cell contains 3.0 x 10-12 grams of DNA.
d) Given that the sexes of Culex are determined by alleles of one gene, males
heterozygous, Mm, and females homozygous mm, illustrate a labeled
chromosomal configuration (involving the symbols Am Ap, BmBp, and CmCp and
the M locus) in a primary spermatocyte at metaphase. Assume that the M locus is
on the Am Ap chromosome and that crossing over has not occurred between the M
locus and the centromere.