EXAM 3 BACK OF BOOK QUESTIONS

How many map units separate two alleles if the recombination frequency is 0.07? a. 700 cM b. 70 cM c. 7 cM d. 0.7 cM

c. 7 cM

In a cross of Aa Bb cc X Aa Bb Cc, what is the probability of obtaining an individual with the genotype AA Bb Cc? a. 1/16 b. 3/16 c. 1/64 d. 3/64

a. 1/16

At metaphase I the kinetochores of sister chromatids are?... a. attached to microtubules from the same pole. b. attached to microtubules from opposite poles. c. held together with cohesin proteins. d. not attached to any microtubules.

a. attached to microtubules from the same pole.

Chiasmata form? a. between homologous chromosomes. b. sister chromatids. c. between replicated copies of the same chromosomes. d. sex chromosomes but not autosomes.

a. between homologous chromosomes.

5. The kinetochore is a structure that functions to.... a. connect the centromere to microtubules. b. connect centrioles to microtubules. c. aid in chromosome condensation. d. aid in chromosomes cohesion.

a. connect the centromere to microtubules.

The map distance between two genes is determined by the? a. recombination frequency. b. frequency of parental types. c. ratio of genes to length of a chromosome. d. ratio of parental to recombinant progeny.

a. recombination frequency.

Cyclin-dependent kinases (Cdks) are regulated by? a. the periodic destruction of cyclins. b. bipolar attachment of chromosomes to the spindle. c. DNA synthesis. d. Both a and b are correct.

a. the periodic destruction of cyclins.

Mutations that affect DNA repair often also affect the accuracy of meiosis. This is because? a. the proteins involved in the repair of double-strand breaks are also involved in crossing over. b. the proteins involved in DNA repair are also involved in sister chromatid cohesion. c. DNA repair only occurs on condensed chromosomes such as those found in meiosis. d.cohesin proteins are also necessary for DNA repair.

a. the proteins involved in the repair of double-strand breaks are also involved in crossing over.

What is the probability of obtaining an individual with the genotype bb from a cross between two individuals with the genotype Bb? a. 1⁄2 b. 1⁄4 c. 1⁄8 d. 0

b. 1/4

What is a nucleosome? a. A region in the cell's nucleus that contains euchromatin b. A region of DNA wound around histone proteins c. A region of a chromosome made up of multiple loops of chromatin d. A 30-nm fiber found in chromatin

b. A region of DNA wound around histone proteins

The F1 plants from the previous question are allowed to self- fertilize. The phenotypic ratio for the F2 should be? a. all purple. c. 3 purple:1 white. b. 1 purple:1 white. c. 3 purple:1 white. d. 3 white:1 purple.

c. 3 purple:1 white.

Which of the following is NOT a distinct feature of meiosis? a. Pairing and exchange of genetic material between homologous chromosomes b. Attachment of sister kinetochores to spindle microtubules c. Movement of sister chromatids to the same pole d. Suppression of DNA replication

b. Attachment of sister

Structurally, meiotic cohesins have different components than mitotic cohesins. This leads to the following functional difference: a. During metaphase I, the sister kinetochores become attached to the same pole. b. Centromeres remain attached during anaphase I of meiosis. c. Centromeres remain attached through both divisions. d. Centromeric cohesins are destroyed at anaphase I, and cohesins along the arms are destroyed at anaphase II.

b. Centromeres remain attached during anaphase I of meiosis.

Chromatin is composed of..... a. RNA and protein. b. DNA and protein. c. sister chromatids. d. chromosomes.

b. DNA and protein

How does DNA replication differ between mitosis and meiosis? a. DNA replication takes less time in meiosis because the cells are haploid. b. During meiosis, there is only one round of replication for two divisions. c. During mitosis, there is only one round of replication every other division. d. DNA replication is exactly the same in mitosis and meiosis.

b. During meiosis, there is only one round of replication for two divisions.

Why is cytokinesis an important part of cell division? a. It is responsible for the proper separation of genetic information. b. It is responsible for the proper separation of the cytoplasmic contents. c. It triggers the movement of a cell through the cell cycle. d. It allows cells to halt at checkpoints.

b. It is responsible for the proper separation of the cytoplasmic contents.

What property distinguished Mendel's investigation from previous studies? a. Mendel used true-breeding pea plants. b. Mendel quantified his results. c. Mendel examined many different traits. d. Mendel examined the segregation of traits.

b. Mendel quantified his results.

What occurs during anaphase of meiosis II? a. The homologous chromosomes align. b. Sister chromatids are pulled to opposite poles. c. Homologous chromosomes are pulled to opposite poles. d. The haploid chromosomes line up.

b. Sister chromatids are pulled to opposite poles.

During the process of spermatogenesis, a nondisjunction event that occurs during the second division would be? a. worse than the first division because all four meiotic products would be aneuploid. b. better than the first division because only two of the four meiotic products would be aneuploid. c. the same outcome as the first division with all four products aneuploid. d. the same outcome as the first division as only two products would be aneuploid.

b. better than the first division because only two of the four meiotic products would be aneuploid.

During anaphase I.... a. sister chromatids separate and move to the poles. b. homologous chromosomes move to opposite poles. c. homologous chromosomes align at the middle of the cell. d. all the chromosomes align independently at the middle of the cell.

b. homologous chromosomes move to opposite poles.

An organism's BLANK is/are determined by its BLANK... a. genotype; phenotype b. phenotype; genotype c. alleles; phenotype d. genes; alleles

b. phenotype; genotype

Crossing over involves each of the following with the exception of? a. the transfer of DNA between two nonsister chromatids. b. the transfer of DNA between two sister chromatids. c. the formation of a synaptonemal complex. d. the alignment of homologous chromosomes.

b. the transfer of DNA between two sister chromatids.

Genetically, prototype- oncogenes act in a dominant fashion. this is because? a. there is only one copy of each proto-oncogene in the genome. b. they act in a gain-of-function fashion to turn on the cell cycle. c. they act in a loss-of-function fashion to turn off the cell cycle. d. they require that both genomic copies are altered to affect function.

b. they act in a gain-of-function fashion to turn on the cell cycle.

As real genetic distance increases, the distance calculated by recombination frequency becomes an? a. overestimate due to multiple crossovers that cannot be scored. b. underestimate due to multiple crossovers that cannot be scored. c. underestimate due to multiple crossovers adding to recombination frequency. d. overestimate due to multiple crossovers adding to recombination frequency.

b. underestimate due to multiple crossovers that cannot be scored.

Genes that are on the same chromosome can show independent assortment.... a. when they are far enough apart for two crossovers to occur. b. when they are far enough apart that odd numbers of crossovers is about equal to even. c. only if recombination is low for that chromosome. d. only if the genes show genomic imprinting.

b. when they are far enough apart that odd numbers of crossovers is about equal to even.

What is the role of cohesin proteins in cell division? a. They organize the DNA of the chromosomes into highly condensed structures. b. They hold the DNA of the sister chromatids together. c. They help the cell divide into two daughter cells. d. They connect microtubules and chromosomes.

b.They hold the DNA of the sister chromatids together.

Why is the white-eye phenotype always observed in males carrying the white-eye allele? a. Because the trait is dominant b. Because the trait is recessive c. Because the allele is located on the X chromosome and males only have one X d. Because the allele is located on the Y chromosome and only males have Y chromosomes

c. Because the allele is located on the X chromosome and males only have one X

Down syndrome is the result of trisomy for chromosome 21. Why is this trisomy viable and trisomy for most other chromosomes is not? a. Chromosome 21 is a large chromosome and excess genetic material is less harmful. b. Chromosome 21 behaves differently in meiosis I than the other chromosomes. c. Chromosome 21 is a small chromosome with few genes so this does less to disrupt the genome. d. Chromosome 21 is less prone to nondisjunction than other chromosomes

c. Chromosome 21 is a small chromosome with few genes so this does less to disrupt the genome.

When you cross true-breeding tall and short tobacco plants you get an F1 that is intermediate in height. When this F1 is self-crossed, it yields an F2 with a continuous distribution of heights. What is the best explanation for these data? a. Height is determined by a single gene with incomplete dominance. b. Height is determined by a single gene with many alleles. c. Height is determined by the additive effects of many genes. d. Height is determined by epistatic genes.

c. Height is determined by the additive effects of many genes.

Which of the following is NOT a part of Mendel's five-element model? a. Traits have alternative forms (what we now call alleles). b. Parents transmit discrete traits to their offspring. c. If an allele is present it will be expressed. d. Traits do not blend.

c. If an allele is present it will be expressed.

Which of the following genotypes due to nondisjunction of sex chromosomes is lethal? a. XXX b. XXY c. OY d. XO

c. OY

How does maternal inheritance of mitochondrial genes differ from sex linkage? a. Mitochondrial genes do not contribute to the phenotype of an individual. b. Because mitochondria are inherited from the mother, only females are affected. c. Since mitochondria are inherited from the mother, females and males are equally affected. d. Mitochondrial genes must be dominant. Sex-linked traits are typically recessive.

c. Since mitochondria are inherited from the mother, females and males are equally affected.

The F1 generation of the monohybrid cross purple (PP) × white (pp) flower pea plants should.... a. all have white flowers. b. all have a light purple or blended appearance. c. all have purple flowers. d. have 3⁄4 purple flowers, and 1⁄4 white flowers.

c. all have purple flowers.

Separation of the sister chromatids occurs during? a. prophase. b. prometaphase. c. anaphase. d. telophase.

c. anaphase.

The main difference between bacterial cell division and eukaryotic cell division is that? a. because bacteria only have one chromosome, they can count the number of copies in the cell. b. eukaryotes mark their chromosomes to identify them and bacteria do not. c. bacterial DNA replication and chromosome segregation are concerted processes but in eukaryotes they are separated in time. d. None of the above is correct.

c. bacterial DNA replication and chromosome segregation are concerted processes but in eukaryotes they are separated in time.

In comparing somatic cells and gametes, somatic cells are? a. diploid with half the number of chromosomes. b. haploid with half the number of chromosomes. c. diploid with twice the number of chromosomes. d. haploid with twice the number of chromosomes.

c. diploid with twice the number of chromosomes.

A recessive sex-linked gene in humans leads to a loss of sweat glands. A woman heterozygous for this will? a. have no sweat glands. b. have normal sweat glands. c. have patches of skin with and without sweat glands. d. have an excess of sweat glands.

c. have patches of skin with and without sweat glands.

The bacterial SMC proteins, eukaryotic cohesin proteins, and condensin proteins share a similar structure. Functionally they all? a. interact with microtubules. b. can act as kinase enzymes. c. interact with DNA to compact or hold strands together. d. connect chromosomes to cytoskeletal elements.

c. interact with DNA to compact or hold strands together.

Which of the following does NOT contribute to genetic diversity? a. Independent assortment b. Recombination c. Metaphase of meiosis II d. Metaphase of meiosis I

c. metaphase of meiosis II

If the two genes in the previous question showed complete linkage, what would you predict for an F2 phenotypic ratio? a. 1 red tall:2 pink short:1 white short b. 1 red tall:2 red short:1 white short c. 1 pink tall:2 red tall: 1white short d. 1 red tall:2 pink tall: 1 white short

d. 1 red tall:2 pink tall: 1 white short

Japanese four o'clocks that are red and tall are crossed to white short ones, producing an F1 that is pink and tall. If these genes assort independently, and the F1 is self-crossed, what would you predict for the ratio of F2 phenotypes? a. 3 red tall:1 white short b. 1 red tall:2 pink short:1 white short c. 3 pink tall:6 red tall:3 white tall:1 pink short:2 red short:1 white short d. 3 red tall:6 pink tall:3 white tall:1 red short:2 pink short:1 white short

d. 3 red tall:6 pink tall:3 white tall:1 red short:2 pink short:1 white short

The A and B genes are 10 cM apart on a chromosome. If an A B/a b heterozygote is testcrossed to a b/a b, how many of each progeny class would you expect out of 100 total progeny? a. 25 A B, 25 a b, 25 A b, 25 a B b. 10 A B, 10 a b b. 45 A B, 45 a b d. 45 A B, 45 a b, 5 A b, 5 a B

d. 45 A B, 45 a b, 5 A b, 5 a B

What steps in the cell cycle represent irreversible commitments? a. The S/G2 checkpoint b. The G1/S checkpoint c. Anaphase d. Both b and c are correct.

d. Both b and c are correct.

What cellular process is responsible for genetic recombination? a. The independent alignment of homologous pairs during meiosis I b. Separation of the homologues in meiosis I c. Separation of the chromatids during meiosis II d. Crossing over between homologues

d. Crossing over between homologues

Which phase of meiosis I is most similar to the comparable phase in mitosis? a. Prophase I b. Metaphase I c. Anaphase I d. Telophase I

d. Telophase I

What are homologous chromosomes? a. The two halves of a replicated chromosome b. Two identical chromosomes from one parent c. Two genetically identical chromosomes, one from each parent d. Two genetically similar chromosomes, one from each parent

d. Two genetically similar chromosomes, one from each parent

Mendel's model assumes that each trait is determined by a single factor with alternate forms. We now know that this is too simplistic and that..... a. a single gene may affect more than one trait. b. a single trait may be affected by more than one gene. c. a single gene always affects only one trait, but traits may be affected by more than one gene. d. a single gene can affect more than one trait, and traits may be affected by more than one gene

d. a single gene can affect more than one trait, and traits may be affected by more than one gene

In an organism's genome, autosomes are? a. the chromosomes that differ between the sexes. b. chromosomes that are involved in sex determination. c. only inherited from the mother (maternal inheritance). d. all of the chromosomes other than sex chromosomes.

d. all of the chromosomes other than sex chromosomes.

binary fission in prokaryotes does not require the? a. replication of DNA b. elongation of the cell. c. separation of daughter cells by septum formation. d. assembly of the nuclear envelope.

d. assembly of the nuclear envelope

The metaphase to anaphase transition involves? a. new force being generated to pull the chromatids apart. b. an increase in force on sister chromatids to pull them apart. c. completing DNA replication of centromeres allowing chromosomes to be pulled apart. d. loss of cohesion between sister chromatids.

d. loss of cohesion between sister chromatids.

In animal cells, cytokinesis is accomplished by a contractile ring containing actin. The related process in bacteria is? a. chromosome segregation, which also appears to use an actinlike protein. b. septation via a ring of FtsZ protein, which is an actinlike protein. c. cytokinesis, which requires formation of a cell plate via vesicular fusion. d. septation via a ring of FtsZ protein, which is a tubulin-like protein.

d. septation via a ring of FtsZ protein, which is a tubulin-like protein.

Phenotypes like height in humans, which show a continuous distribution, are usually the result of? a. an alteration of dominance for multiple alleles of a single gene. b. the presence of multiple alleles for a single gene. c. the action of one gene on multiple phenotypes. d. the action of multiple genes on a single phenotype.

d. the action of multiple genes on a single phenotype.