sample exam 3
39) Glucose-6-phosphate dehydrogenase deficiency (G6PD) is inherited as a recessive allele of an 39) X-linked gene in humans. A woman whose father suffered from G6PD marries a normal man. (a) What proportion of their sons is expected to be G6PD? (b) If the husband was not normal but was G6PD deficient, would you change your answer in part (a)?
(a) 1/2; (b) no
A man has polydactyly (six fingers on each hand and six toes on each foot). His wife and their daughter have a normal number of digits. Having extra digits is a dominant trait. The couple's second child has extra digits. What is the probability that their next (third) child will have extra digits?
1/2
Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails (t). What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails?
1/2
In the cross AaBbCc × AaBbCc, what is the probability of producing the genotype AABBCC?
1/64
Cinnabar eyes is a sex-linked, recessive characteristic in fruit flies. If a female having cinnabar eyes 40) is crossed with a wild-type male, what percentage of the F1 males will have cinnabar eyes?
100%
A homozygous tomato plant with red fruit and yellow flowers was crossed with a homozygous 31) tomato plant with golden fruit and white flowers. The F1 all had red fruit and yellow flowers. The F1 were testcrossed by crossing them to homozygous recessive individuals and the following offspring were obtained: Red fruit and yellow flowers 41 Red fruit and white flowers 7 Golden fruit and yellow flowers 8 Golden fruit and white flowers 44 What is the % recombination between these genes?
15
The diploid number of a roundworm species is 4. Assuming there is no crossover, and that random 32) segregation of homologues occurs during meiosis, how many different possible combinations of chromosomes might there be in the offspring (not including variety generated by crossing over)?
16
You've isolated DNA from a newly found species. Guanine makes up 34% of the nucleotides in a sample of DNA from the organism. Approximately what percentage of the nucleotides in this sample will be adenine?
16%
A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms would be found at the end of S and the end of G2?
16; 16
When Mendel crossed true breeding yellow-seeded and green-seeded pea plants, all the offspring 29) were yellow seeded. When he took these F1 yellow-seeded plants and crossed them to green-seeded plants, what genotypic ratio was expected?
1:1
Quaking aspen can send out underground stems for asexual reproduction. Sexual reproduction is 10) not as common, but when it does happen, the haploid gametes have 19 chromosomes. How many chromosomes are in the cells of the underground stems?
38
Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive 30) thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?
DNA in both daughter cells would be radioactive.
A space probe returns with a culture of a microorganism found below the ice on Jupiter's moon, Europa. Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in (15)^N medium for several generations and then transfer them to (14)^N medium for two generations. Which pattern in the figure above would you expect if the DNA was replicated in a semiconservative manner?
E, the tube with dna at the two top spots: 14N DNA 14N-15N hybrid DNA
A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail 18) length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?
HT
Which of the following scientists demonstrated that DNA was the molecule that entered T2 bacteriophage and thus likely the unit of inheritance?
Hershey & Chase
If a cell has completed meiosis I and is just beginning meiosis II, which of the following is an appropriate description of its contents?
It has half the amount of DNA as the cell that began meiosis.
The cyclin component of MPF is destroyed toward the end of which phase?
M
What is a major difference between eukaryotic DNA replication and prokaryotic DNA replication?
Prokaryotic chromosomes have a single origin of replication, while eukaryotic chromosomes have multiple origins of replication
What happens if MPF (mitosis-promoting factor) is introduced into immature frog oocytes that are 37) arrested in G2?
The cells enter mitosis.
A research team began a study of a cultured cell line. Their preliminary observations showed them that the cell line did not exhibit either density-dependent inhibition or anchorage dependence. What could they conclude right away?
The cells show characteristics of tumors.
What does a frequency of recombination of 50% indicate?
The two genes are likely to be located on different chromosomes.
What was the most significant conclusion that Gregor Mendel drew from his experiments with pea 38) plants?
Traits are inherited in discrete units and are not the results of "blending."
Refer to the drawings in the figure below of a single pair of homologous chromosomes as they might appear during various stages of either mitosis or meiosis, and answer the following question. Which diagram represents anaphase II of meiosis?
V (sister chromatids splitting?)
The following is a map of four genes on a chromosome. A (5) W (3) E (12) G Between which two genes would you expect the lowest frequency of recombination?
W and E
SRY is best described as _____.
a gene region present on the Y chromosome that triggers male development
Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely _____.
a plant cell in the process of cytokinesis
Homologous chromosomes _____.
carry information for the same traits
MPF is a dimer consisting of _____
cyclin and a cyclin-dependent kinase
Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cactuses have dull spines. At the same time, a second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. The relationship between genes S and N is an example of _____.
epistasis
What is the final result of mitosis in a human?
genetically identical 2n somatic cells
The human X and Y chromosomes _____.
include genes that determine an individual's sex
Independent assortment of chromosomes occurs during _____
meiosis I only
Inheritance patterns cannot always be explained by Mendel's models of inheritance. If a pair of homologous chromosomes fails to separate during meiosis I, select the choice that shows the chromosome number of the four resulting gametes with respect to the normal haploid number (n)?
n+1; n+1; n-1; n-1
What is the function of topoisomerase?
relieving strain in the DNA ahead of the replication fork
Which of the following occurs in meiosis but not in mitosis?
synapsis of chromosomes
In the polymerization of DNA, a phosphodiester bond is formed between a phosphate group of the 8) nucleotide being added and _____ of the last nucleotide in the polymer.
the 3' OH
In human and many other eukaryotic species' cells, the nuclear membrane has to disappear to 13) permit _____.
the attachment of microtubules to kinetochores
The leading and the lagging strands differ in that _____.
the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction
In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange 22) color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of an orange female and a black male?
tortoiseshell females; orange males
The following questions refer to the pedigree chart in the figure below for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. gen I- white square (ww) and black circle (Ww) What is the genotype of individual II-5? (unrelated white circle that mates with a dark square and produces a dark square and a light square and light circle)
ww
