Exam 3 practice Flashcards
1
Q
- One of the key differences between meiosis and mitosis is
a. there is only 1 round of DNA replication before mitosis, but 2 rounds of replication before meiosis.
b. cells divide once in mitosis, but twice in meiosis.
c. homologous chromosomes pair up in mitosis, but not in meiosis.
d. A & B
e. All of the above
A
B.cells divide once in mitosis, but twice in meiosis.
2
Q
- Meiosis II is also referred to as the equational division. This is due to
a. crossing over.
b. pairing of homologs.
c. separation of chromatids.
d. separation of homologs.
e. None of the above
A
separation of chromatids.
3
Q
- In a haploid organism, most mitosis occurs
a. after fertilization and before meiosis.
b. after meiosis and before fertilization.
c. between meiosis I and II.
d. during G1.
e. in diploid cells.
A
after meiosis and before fertilization.
4
Q
- Diploid cells of the fruit fly Drosophila have eight chromosomes. How many chromosomes does a Drosophila gamete have?
a. 1
b. 2
c. 4
d. 8
e. 16
A
4
5
Q
- Accidents during meiosis that can result in trisomies and monosomies are called
a. nondisjunctions.
b. inversions.
c. reciprocal translocations.
d. recombinations.
e. acrocentricities.
A
a.
6
Q
- The site on the chromosome occupied by a gene is called a(n)
a. allele.
b. region.
c. locus.
d. type.
e. phenotype.
A
c.
7
Q
- Mendel’s conclusion that individuals consist of two “factors” and pass on only one of those factors to the next generation is the basis for
a. the law of segregation.
b. the law of independent assortment.
c. the law of dominance.
d. the law of linkage.
e. I fought the law and the law won.
A
a
8
Q
- Which of the following methods was not used by Mendel in his study of the genetics of the garden pea?
a. Maintenance of true-breeding lines
b. Cross-pollination
c. Microscopy
d. Production of hybrid plants
e. Quantitative analysis of results
A
c
9
Q
- Which of the following is a possible gamete for an individual with the genotype PPrr?
a. PP
b. Pr
c. pr
d. rr
e. Rp
A
b
10
Q
For questions 12-14, refer to the schmoos. Two different groups of imaginary schmoos live in geographically separated locations and rarely interbreed. On one occasion, a big-footed white schmoo does mate with a small-footed brown schmoo. Three offspring result: one big-footed brown schmoo and two small-footed brown schmoos.
- Which statement about the inheritance of color in schmoos is most likely to be correct?
a. Brown is dominant to white
b. White is dominant to brown
c. White and brown are codominant
d. A & C
e. This cannot be answered without more information - Which statement about the inheritance of footedness in schmoos is most likely to be correct?
a. Big is dominant to small
b. Small is dominant to big
c. Big and small are codominant
d. A & C
e. This cannot be answered without more information - If big feet (B) in schmoos is dominant to small feet (b), the genotype of the big-footed white parent schmoo with respect to the foot gene can
a. only be bb.
b. only be BB.
c. only be Bb.
d. either be bb or BB.
e. either be bb or Bb.
A
a
e
c
11
Q
- Classical albinism results from a recessive allele. Which of the following is the expected ratio for the progeny when a normally pigmented male with an albino father has children with an albino woman?
a. ¾ normal; ¼ albino
b. ¾ albino; ¼ normal
c. ½ normal; ½ albino
d. All normal
e. All albino
A
c
12
Q
- Mendel performed a cross between individuals heterozygous for three different traits: yellow versus green seeds (yellow is dominant), red versus white flowers (red is dominant), and green versus yellow pods (green is dominant). What fraction of the offspring would have been expected to have yellow seeds, red flowers, and yellow pods?
a. 27/64
b. 12/64
c. 9/64
d. 6/64
e. 3/64
A
a
13
Q
- The ABO blood groups in humans are determined by a multiple allelic system in which IA and IB are codominant and are dominant to iO. If an infant born to a type O mother also is type O, possible phenotypes for the father are
a. O or A.
b. A or O.
c. O only.
d. O, A, or B.
e. impossible to determine.
A
d
14
Q
- Epistasis refers to
a. a group of genes that are close together.
b. the equal interaction of two genes so that a new phenotype is produced.
c. the expression of two genes in the same individual.
d. the linear order of genes on a chromosome.
e. the expression of one gene masking the expression of another.
A
e
15
Q
- If 3 unlinked genes control a trait and an individual is heterozygous for 2 genes and homozygous for 1 gene, how many different gametes are possible?
a. 3
b. 4
c. 6
d. 8
e. 12
A
b
16
Q
- White coat color in mice is caused by an allele recessive to the dark allele for dark coat color. Twenty-four mice resulting from a cross between individuals heterozygous for this gene would be
a. 6 dark; 18 white
b. 18 dark; 6 white
c. 12 dark; 12 white
d. All dark
e. All white
A
b
17
Q
- Sex in humans is determined by
a. a gene called SRY found on the Y chromosome.
b. a gene called SRY found on the X chromosome.
c. the ratio of sex determinants found on the autosomes versus the sex determinants found on the Y chromosome.
d. the ratio of sex determinant found on the autosomes versus the sex determinants found on the X chromosome.
e. the simple presence or absence of the Y chromosome.
A
a
18
Q
- When reciprocal crosses produce identical results, the trait is
a. sex-linked.
b. not sex-linked.
c. not autosomally inherited.
d. A & C
e. B & C
A
b
19
Q
- In Netherlands dwarf rabbits, a gene with two alleles showing incomplete dominance produces three outcomes. Rabbits that are homozygous for one allele are small; individuals that are homozygous for the other allele die during development; individuals that are heterozygous are dwarf. If two dwarf rabbits are mated, what proportion of their surviving offspring are likely to be dwarf?
a. 1/4
b. 1/3
c. 1/2
d. 2/3
e. All
A
d
20
Q
- In humans, spotted teeth are caused by a dominant sex-linked gene. A man with spotted teeth whose father had normal teeth marries a woman with normal teeth. Therefore,
a. all of their daughters will have normal teeth.
b. all of their daughters will have spotted teeth.
c. all of their children will have spotted teeth.
d. half of their sons will have spotted teeth.
e. all of their sons will have spotted teeth.
A
b
21
Q
- A person’s genotype is AaBb for two genes linked on the same chromosome. If the two dominant alleles are on one chromosome and the two recessive alleles are on the other homologous chromosome, which of the following statements is true?
a. Gametes AB, Ab, aB, and ab will be produced at an equal frequency.
b. Gametes AB and ab will be produced at a higher frequency than Ab and aB.
c. Gametes Ab and aB will be produced at a higher frequency than AB and ab.
d. Gametes AB and ab are the only possible gametes.
e. None of the above
A
b
22
Q
- If the distribution of a character in a population is continuous, (ie. a bell shaped curve occurs when degree of trait is plotted against frequency) you would assume that the character is
a. not controlled by genes.
b. controlled by more than one gene.
c. controlled by multiple alleles of the same gene.
d. is heavily influenced by the environment.
e. None of the above
A
b
23
Q
- How does X chromosome inactivation contribute to genetic diversity?
a. It controls the number and kind of genes expressed on an X chromosome.
b. It determines which X chromosome is expressed in a male.
c. It allows for expression of either the maternal or paternal X chromosome in different cells.
d. It enhances expression of Y-linked genes in males.
e. It allows the enhancement of transcription of genes on the X chromosome in males.
A
c
24
Q
- The adaptor molecule used by the cell to decode the nucleotide information of mRNA and convert it to protein information is
a. tRNA.
b. a promoter.
c. RNA polymerase.
d. DNA polymerase.
e. an amino acid.
A
a
25
Q
- Which of the following would be an example of an ambiguous genetic code?
a. One with 61 codons for 20 amino acids.
b. One in which UUU and UUA both code for phenylalanine.
c. One in which CCU could code for either alanine or leucine.
d. All of the above
e. None of the above
A
c
26
Q
- Promoters are made of
a. proteins.
b. carbohydrates.
c. lipids.
d. nucleic acids.
e. amino acids.
A
d
27
Q
- RNA polymerase uses the ________ DNA template to synthesize a ________ mRNA.
a. 5’ to 3’; 5’ to 3’
b. 3’ to 5’; 3’ to 5’
c. 5’ to 3’; 3’ to 5’
d. 3’ to 5’; 5’ to 3’
e. Examples of all of the above have been found
A
d
28
Q
- The three codons in the genetic code that do not specify amino acids are called
a. missense codons.
b. start codons.
c. stop codons.
d. promoters.
e. initiator codons.
A
c
29
Q
- The central dogma of molecular biology states that _____ is transcribed into _____, which is translated into _____.
a. A gene; polypeptides; a gene product
b. Protein; DNA; RNA
c. DNA; mRNA; tRNA
d. DNA; RNA; protein
e. RNA; DNA; protein
A
d
30
Q
- Tetracycline is an antibiotic that binds to the ribosome of bacteria. These bacteria die because
a. DNA is unable to be transcribed.
b. mRNA is unable to be exported to the cytoplasm.
c. mRNA is spliced incorrectly, producing wrong proteins.
d. the polypeptide chain is unable to be elongated.
e. proteins lose their correct folding structure.
A
d
31
Q
- Which of the following statements is/are true of silent mutations?
a. They are often due to changes in the third position of a codon of a protein-coding region.
b. They may occur in introns or untranslated regions of a gene.
c. They are always somatic cell mutations that do not get transmitted from parent to child.
d. A & B
e. All of the above
A
d
32
Q
- The three basic parts of an operon are the
a. promoter, the operator, and two or more structural genes.
b. promoter, the structural genes, and the termination codons.
c. promoter, the mRNA, and the termination codons.
d. structural genes, the mRNA, and the tRNAs.
e. None of the above
A
a
33
Q
- You are examining the mRNA transcript and protein synthesized from a sequence of DNA that you think contains a mutation. In comparing these products to the normal products, you notice that the mRNA is a normal length, but the protein is shorter than it should be and nonfunctional. What is the most likely explanation?
a. A deletion of several codons in the DNA
b. A point mutation in the DNA
c. A mutation in the first codon of the DNA
d. Conversion of a normal codon to a stop codon
e. A deletion of a single base of DNA
A
d
34
Q
- Which of the following is not a way to regulate the production of a final protein product?
a. Hydrolyze DNA, preventing transcription
b. Down regulate mRNA transcription
c. Hydrolyze mRNA, preventing translation
d. Prevent mRNA translation at the ribosome
e. Hydrolyze the protein after its made
A
a
35
Q
- In the presence of lactose, the lac operon
a. is turned off by the repressor.
b. turns on when the repressor is inactivated.
c. is turned on by an activator.
d. turns off when lactose binds to the operator.
e. turns on when lactose binds to the promoter.
A
b
36
Q
- How do enhancers activate a gene which is distant to its position on a chromosome?
a. They modify the structure of RNA polymerase, which is free to diffuse in the direction of the gene which will be activated.
b. They collect activator proteins which promote transcription, then are able to contact the initiation complex (to which RNA polymerase II is bound), stimulating transcription.
c. Enhancers are proteins which stimulate transcription, and can move throughout the nucleoplasm.
d. Regions of DNA far distant from an actual gene are catalytic, and can create end-products which activate RNA polymerase II.
e. Enhancers modify DNA polymerase to create extra copies of the gene, increasing the DNA available for transcription.
A
b
37
Q
- Which of the following methods of gene regulation do eukaryotes and prokaryotes appear to have in common?
a. Elaborate packing of DNA in chromosomes
b. Activator and repressor proteins, which attach to DNA
c. The addition of a cap and tail to mRNA after transcription
d. lac and trp operons
e. The removal of noncoding portions of RNA
A
b
38
Q
- How does a zygote differ from an ovum (egg cell)?
a. A zygote has more chromosomes
b. A zygote is smaller
c. A zygote consists of more than one cell
d. A zygote is much larger
e. A zygote divides by meiosis
A
a
39
Q
- After a sperm penetrates an egg, the fertilization envelope
a. secretes important hormones.
b. enables the fertilized egg to implant in the wall of the uterus.
c. prevents more than one sperm from entering the egg.
d. attracts additional sperm to the egg.
e. activates the egg for embryonic development.
A
c
40
Q
- In an experiment, a researcher colored a bit of tissue on the outside of a frog gastrula with an orange fluorescent dye. The embryo developed normally. When the tadpole was placed under an ultraviolet light, which of the following glowed bright orange?
a. The heart
b. The pancreas
c. The brain
d. The stomach
e. The liver
A
c
41
Q
- Which of the following characterizes neurulation?
a. The notochord becomes a neural tube.
b. The neural tube is formed from ectoderm.
c. A neural tube forms around the notochord.
d. The neural tube forms somites.
e. In birds, the neural tube forms from the primitive streak.
A
b
