Unit 3 Bio Quiz Questions

In cats, black fur color is caused by an X-linked allele; the other allele at this locus causes orange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect from the cross of a black female and an orange male? tortoiseshell females; black males orange females; orange males black females; orange males orange females; black males tortoiseshell females; tortoiseshell males

A

In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white? roan × roan red × white white × roan red × roan The answer cannot be determined from the information provided.

A

The beginning of anaphase is indicated by which of the following? Cohesin is cleaved enzymatically. Spindle microtubules begin to polymerize. Cohesin attaches the sister chromatids to each other. Kinetochores attach to the metaphase plate. Chromatids lose their kinetochores.

A

A new DNA strand elongates only in the 5' to 3' direction because DNA polymerase begins adding nucleotides at the 5' end of the template. DNA polymerase can only add nucleotides to the free 3' end. Okazaki fragments prevent elongation in the 3' to 5' direction. the polarity of the DNA molecule prevents addition of nucleotides at the 3' end. replication must progress toward the replication fork.

B

If an organism is diploid and a certain gene found in the organism has 18 known alleles (variants), then any given organism of that species can/must have which of the following? up to, but not more than, 18 different traits at most, 2 alleles for that gene a haploid number of 9 chromosomes up to 18 genes for that trait up to 18 chromosomes with that gene

B

In his transformation experiments, what did Griffith observe? Mice infected with a pathogenic strain of bacteria can spread the infection to other mice. Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form. Infecting mice with nonpathogenic strains of bacteria makes them resistant to pathogenic strains. Mutant mice were resistant to bacterial infections. Mixing a heat-killed nonpathogenic strain of bacteria with a living pathogenic strain makes the pathogenic strain nonpathogenic.

B

Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle did the nucleus contain 6 picograms of DNA? G1 G2 M G0 S

B

What do we mean when we use the terms monohybrid cross and dihybrid cross? A monohybrid cross results in a 9:3:3:1 ratio, whereas a dihybrid cross gives a 3:1 ratio. A dihybrid cross involves organisms that are heterozygous for two characters, and a monohybrid cross involves only one. A monohybrid cross produces a single progeny, whereas a dihybrid cross produces two progeny. A monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two generations. A monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents.

B

What is produced if a cell divides by mitosis but does not undergo cytokinesis? two cells, one cell containing two nuclei and a second cell without a nucleus one cell with two nuclei, each identical to the nucleus of the parent cell one cell with one nucleus containing half of the genetic material of the parent cell two cells, each cell with half of the genetic material of the parent cell

B

Which of the following does not occur during mitosis? separation of the spindle poles replication of the DNA separation of sister chromatids spindle formation condensation of the chromosomes

B

Which of the following is a true statement about sexual vs. asexual reproduction? In asexual reproduction, offspring are produced by fertilization without meiosis. In sexual reproduction, individuals transmit 50% of their genes to each of their offspring. Asexual reproduction, but not sexual reproduction, is characteristic of plants and fungi. Asexual reproduction produces only haploid offspring. Sexual reproduction requires that parents be diploid.

B

Which of the following occurs in meiosis but not in mitosis? chromosome replication synapsis of chromosomes condensation of chromatin production of daughter cells alignment of chromosomes at the equator

B

Cells from advanced malignant tumors often have very abnormal chromosomes as well as an abnormal number of chromosomes. What might explain the association between malignant tumors and chromosomal abnormalities? Cancer cells are no longer anchorage dependent. Cancer cells are no longer density dependent. Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities. Chromosomally abnormal cells still have normal metabolism. Transformation introduces new chromosomes into cells.

C

Mendel's second law of independent assortment has its basis in which of the following events of meiosis I? crossing over separation of cells at telophase alignment of tetrads at the equator separation of homologs at anaphase synapsis of homologous chromosomes

C

The following questions are based on Figure 9.3. f1q14g1.jpg Figure 9.3 At which of the numbered regions would you expect to find cells at metaphase? II only I and IV III only IV only V only

C

Which of the following help(s) to hold the DNA strands apart while they are being replicated? ligase exonuclease single-strand binding proteins DNA polymerase primase

C

Which of the following provides an example of epistasis? The allele b17 produces a dominant phenotype, although b1 through b16 do not. Recessive genotypes for each of two genes (aabb) result in an albino corn snake. In rabbits and many other mammals, one genotype (ee) prevents any fur color from developing. In cacti, there are several genes for the type of spines. In Drosophila (fruit flies), white eyes can be due to an X-linked gene or to a combination of other genes.

C

A couple has a child with Down syndrome. The mother is 39 years old at the time of delivery. Which of the following is the most probable cause of the child's condition? The mother had a chromosomal duplication. The woman inherited this tendency from her parents. One member of the couple underwent nondisjunction in somatic cell production. One member of the couple underwent nondisjunction in gamete production. One member of the couple carried a translocation.

D

After telophase I of meiosis, the chromosomal makeup of each daughter cell is A tetraploid, and the chromosomes are each composed of two chromatids. B diploid, and the chromosomes are each composed of two chromatids. C diploid, and the chromosomes are each composed of a single chromatid. D haploid, and the chromosomes are each composed of two chromatids. E haploid, and the chromosomes are each composed of a single chromatid.

D

All female mammals have one active X chromosome per cell instead of two. What causes this? attachment of methyl (CH3) groups to the X chromosome that will remain active activation of the BARR gene on one X chromosome, which then becomes inactive inactivation of the XIST gene on the X chromosome derived from the male parent activation of the XIST gene on the X chromosome that will become the Barr body crossing over between the XIST gene on one X chromosome and a related gene on an autosome

D

Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base? Neither of the two daughter cells would be radioactive. One of the daughter cells, but not the other, would have radioactive DNA. All four bases of the DNA would be radioactive. DNA in both daughter cells would be radioactive. Radioactive thymine would pair with nonradioactive guanine.

D

The fact that all seven of the pea plant traits studied by Mendel obeyed the principle of independent assortment most probably indicates which of the following? The formation of gametes in plants occurs by mitosis only. None of the traits obeyed the law of segregation. The diploid number of chromosomes in the pea plants was 7. All of the genes controlling the traits behaved as if they were on different chromosomes. All of the genes controlling the traits were located on the same chromosome.

D

What is the most logical sequence of steps for splicing foreign DNA into a plasmid and inserting the plasmid into a bacterium? I. Transform bacteria with a recombinant DNA molecule. II. Cut the plasmid DNA using restriction enzymes. III. Extract plasmid DNA from bacterial cells. IV. Hydrogen-bond the plasmid DNA to nonplasmid DNA fragments. V. Use ligase to seal plasmid DNA to nonplasmid DNA. III, IV, V, I, II IV, V, I, II, III I, II, IV, III, V III, II, IV, V, I II, III, V, IV, I

D

Which of the following is the meaning of the chromosome theory of inheritance as expressed in the early 20th century? Natural selection acts on certain chromosome arrays rather than on genes. Homologous chromosomes give rise to some genes and crossover chromosomes to other genes. No more than a single pair of chromosomes can be found in a healthy normal cell. Mendelian genes are at specific loci on the chromosome and in turn segregate during meiosis. Individuals inherit particular chromosomes attached to genes.

D

Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor? enhanced anchorage dependence inability to form spindles changes in the order of cell cycle stages inability of chromosomes to meet at the metaphase plate lack of appropriate cell death

E

Movement of the chromosomes during anaphase would be most affected by a drug that prevents elongation of microtubules. formation of a cleavage furrow. cell wall formation. nuclear envelope breakdown. shortening of microtubules.

E

The individual with genotype AaBbCCDdEE can make many kinds of gametes. Which of the following is the major reason? segregation of maternal and paternal alleles crossing over during prophase I recurrent mutations forming new alleles the tendency for dominant alleles to segregate together different possible assortment of chromosomes into gametes

E

What is the function of topoisomerase? A elongating new DNA at a replication fork by adding nucleotides to the existing chain B adding methyl groups to bases of DNA C stabilizing single-stranded DNA at the replication fork D unwinding of the double helix E relieving strain in the DNA ahead of the replication fork

E

When crossing an organism that is homozygous recessive for a single trait with a heterozygote, what is the chance of producing an offspring with the homozygous recessive phenotype? 25% 100% 75% 0% 50%

E

Which of the following happens at the conclusion of meiosis I? The chromosome number per cell is conserved. Cohesins are cleaved at the centromeres. Sister chromatids are separated. Four daughter cells are formed. Homologous chromosomes of a pair are separated from each other.

E

Which of the following statements describes chromatin? Euchromatin is not transcribed, whereas heterochromatin is transcribed. Heterochromatin is composed of DNA, whereas euchromatin is made of DNA and RNA. Only euchromatin is visible under the light microscope. Both heterochromatin and euchromatin are found in the cytoplasm. Heterochromatin is highly condensed, whereas euchromatin is less compact.

E

What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized? Polymerase can work on only one strand at a time. DNA polymerase can join new nucleotides only to the 3' end of a growing strand. Helicases and single-strand binding proteins work at the 5' end. DNA ligase works only in the 3' → 5' direction. The origins of replication occur only at the 5' end.

b

What is the function of DNA polymerase III? to unwind the DNA helix during replication to degrade damaged DNA molecules to add nucleotides to the 3' end of a growing DNA strand to rejoin the two DNA strands (one new and one old) after replication to seal together the broken ends of DNA strands

c

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? a It synthesizes RNA nucleotides to make a primer. b It unwinds the parental double helix. c It joins Okazaki fragments together. d It catalyzes the lengthening of telomeres. e It stabilizes the unwound parental DNA.

c

The leading and the lagging strands differ in that A the lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. B the leading strand is synthesized at twice the rate of the lagging strand. C the leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end. D 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.

d

Which of the following statements is true of histones? A Each nucleosome consists of two molecules of histone H1. B The mass of histone in chromatin is approximately nine times the mass of DNA. C Histones are found in mammals, but not in other animals or in plants or fungi. D Histone H1 is not present in the nucleosome bead; instead, it draws the nucleosomes together. E The carboxyl end of each histone extends outward from the nucleosome and is called a "histone tail."

d

Use Figure 13.3 to answer the following question. f1q28g1.jpg Figure 13.3 Which enzyme was used to produce the molecule in Figure 13.3? transcriptase RNA polymerase ligase DNA polymerase a restriction enzyme

e

Why do histones bind tightly to DNA? Histones are negatively charged, and DNA is positively charged. Histones are highly hydrophobic, and DNA is hydrophilic. Histones are covalently linked to the DNA. Both histones and DNA are strongly hydrophobic. Histones are positively charged, and DNA is negatively charged.

e