Campbell Biology EXAM 3

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1

The red color of the flower is expressed during subsequent generations. This red color indicates which of the following?

Phenotype

2

Mendel's second law of independent assortment has its basis in which of the following events of meiosis I?

Alignment of tetrads at the equator

3

The red color of the flower is expressed most often during subsequent generations in cross breeding with white flowering plants. This red color indicates which of the following?

A&C Expression due to dominant allele, Expression due to recessive allele

4

Mendel's observation of the segregation of alleles in gamete formation has its basis in which of the following phases of cell division?

Anaphase I of meiosis

5

To determine the genotype of a frequently seen orange flowering plant in a population, the plant will be mated with ___________ plant.

Homozygous recessive

6

Which of the following is an example of polygenic inheritance?

skin pigmentation in humans

7

Marfan syndrome in humans is caused by an abnormality of the connective tissue protein fibril in. Patients are usually very tall and thin, with long spindly fingers, curvature of the spine, sometimes weakened arterial walls, and sometimes ocular problems, such as lens dislocation. Which of the following would you conclude about Marfan syndrome from this information?

It is pleiotropic.

8

Which of the following describes the ability of a single allele to have multiple phenotypic effects?

Pleiotropy

9

A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates

Dominance

10

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBBCCDdEe?

8, explanation Aa (2) x BB (1) x CC (1) x Dd (2) x Ee (2) = 8 ( 2x2=4x2 )

11

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?

½

12

Which of the following provides an example of epistasis?

In rabbits and many other mammals, one genotype (cc) prevents any fur color from developing.

13

Genes on the same chromosome may be __________, meaning that they do not sort independently.

linked

14

Which of the following statements is true of linkage?

The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.

15

The phenotype of a character most often seen in a natural population is called

wild type.

16

SRY is best described as

a gene region present on the Y chromosome that triggers male development.

17

Which of the following is the meaning of the chromosome theory of inheritance as expressed in the early twentieth century?

Mendelian genes are at specific loci on the chromosome and, in turn, segregate during meiosis.

18

Males are more often affected by sex-linked traits than females because

males are hemizygous for the X chromosome

19

Which of the following statements is true of linkage?

The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them

20

Which of the following results from Griffith’s experiment is an example of transformation?

Mouse dies after being injected with a mixture of heat-killed S and living R cells.

21

In the polymerization of DNA, a phosphodiester bond is formed between a phosphate group of the nucleotide being added and _________ of the last nucleotide in the polymer.

the 3' OH

22

Replication in prokaryotes differs from replication in eukaryotes for which of the following reasons?

Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

23

In DNA from any species, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.-Which of the scientist was responsible for this discovery?

Erwin Chargaff

24

What is meant by the description "antiparallel" regarding the strands that make up DNA?

The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.

25

In E. coli, which enzyme catalyzes the elongation of a new DNA strand in the 5' → 3' direction?

DNA polymerase III

26

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?

It joins Okazaki fragments together.

27

Heterochromatin is _________, whereas euchromatin is _________.

highly condensed, less compact

28

Which of the following helps to hold the DNA strands apart while they are being replicated?

single-strand DNA binding proteins

29

In the process of transcription, __________

RNA is synthesized

30

_________ are noncoding segments of mRNA, and __________ are segments that code for functional products.

Introns, exons

31

The first event to take place in translation in eukaryotes is

the small subunit of the ribosome recognizes and attaches to the cap of mRNA.

32

A particular triplet of bases in the template strand of DNA is 5' AGT 3'. The corresponding codon for the mRNA transcribed is __________.

3' UCA 5'

33

Codons are part of the __________

mRNA

34

__________carries an amino acid to a strand of mRNA.

TRNA

35

Once researchers identified DNA as the unit of inheritance, they asked how information was transferred from the DNA in the nucleus to the site of protein synthesis in the cytoplasm. What is the mechanism of information transfer in eukaryotes?

Messenger RNA is transcribed from a single gene and transfers information from the DNA in the nucleus to the cytoplasm, where protein synthesis takes place.

36

A signal peptide __________.

helps target a protein to the ER

37

What is the characteristic of Okazaki fragments?

5’ RNA nucleotides, DNA nucleotides 3’

38

Role of DNA ligase

It joins Okazaki fragments together

39

Function of topoisomerase

Relieving strain in the DNA ahead of the replication fork

40

In humans, ABO blood types refer to glycoproteins in the membranes of red blood cells. There are three alleles for this autosomal gene: IA, IB, and i. The IAallele codes for the A glycoprotein, The IB allele codes for the B glycoprotein, and the i allele doesn't code for any membrane glycoprotein. IA and IB are codominant, and i is recessive to both IA and IB. People with type A blood have the genotypes IAIA or IAi, people with type B blood are IBIB or IBi, people with type AB blood are IAIB, and people with type O blood are ii. If a woman with type AB blood marries a man with type O blood, which of the following blood types could their children possibly have?

A and B

41

Which of the following statements is true of linkage?

The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.

42

When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?

The gene involved is on the X chromosome

43

The following is a map of four genes on a chromosome.

Between which two genes in Figure 15.1 would you expect the highest frequency of recombination?

A and G

44

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

45

In certain plants, tall is dominant to short. If a heterozygous plant is crossed with a homozygous tall plant, what is the probability that the offspring will be short?

0

46

SRY is best described in which of the following ways?

  • A gene region present on the Y chromosome that triggers male development.
47

The following question refers to the pedigree chart in Figure 14.2 for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle.

What is the probability that individual III-1 is Ww?

E

48

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?

One member of the couple underwent nondisjunction in gamete production.

49

Mendel's second law of independent assortment has its basis in which of the following events of meiosis I?

Alignment of tetrads at the equator

50

The following question refers to the pedigree chart in Figure 14.2 for a family, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle.

What is the likelihood that the progeny of IV-3 and IV-4 will have the trait?

50%

51

Which of the following is the best explanation for the fact that most transduction pathways have multiple steps?

  • Multiple steps provide for greater possible amplification of a signal.
52

The pedigree in Figure 15.3 shows the transmission of a trait in a particular family.

Based on this pattern of transmission, the trait is most likely:

Mitochondrial

53

Which of the following is the meaning of the chromosome theory of inheritance as expressed in the early 20th century?

Mendelian genes are at specific loci on the chromosome and in turn segregate during meiosis.

54

In a human karyotype, chromosomes are arranged in 23 pairs. If we choose one of these pairs, such as pair 14, which of the following do the two chromosomes of the pair have in common

Length, centromere position, staining pattern, and traits coded for by their genes.

55

Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by which of the following?

  • Environmental factors such as soil pH.
56

All female mammals have one active X chromosome per cell instead of two. What causes this?

Activation of the XIST gene on the X chromosome that will become the Barr body.

57

Marfan syndrome in humans is caused by an abnormality of the connective tissue protein fibrillin. Patients are usually very tall and thin, with long spindly fingers, curvature of the spine, sometimes weakened arterial walls, and sometimes ocular problems, such as lens dislocation. Which of the following would you conclude about Marfan syndrome from this information?

It is pleiotropic.

58

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?

50%

59

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

60

At which phase is it preferable to obtain chromosomes to prepare a karyotype?

Late prophase or metaphase

61

What does a frequency of recombination of 50% indicate?

The two genes are likely to be located on different chromosomes.

62

A black guinea pig crossed with an albino guinea pig produced twelve black offspring. When the albino was crossed with a second black animal, six blacks and six albinos were obtained. What is the best explanation for this genetic situation?

Albino is recessive; black is dominant.

63

One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called?

Translocation

64

Males are more often affected by sex-linked traits than females because:

Males are hemizygous for the X chromosome.

65

In humans, clear gender differentiation occurs, not at fertilization, but after the second month of gestation. What is the first event of this differentiation?

Activation of SRY in male embryos and masculinization of the gonads

66

What is a syndrome?

A group of traits typically found in conjunction with a particular chromosomal aberration or gene mutation

67

Phenylketonuria (PKU) is a recessive human disorder in which an individual cannot appropriately metabolize a particular amino acid. The amino acid is not otherwise produced by humans. Therefore, the most efficient and effective treatment is which of the following?

  • Regulate the diet of the affected persons to severely limit the uptake of the amino acid.
68

Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties?

One phenotype was completely dominant over another.

69

Which of the following provides an example of epistasis?

In rabbits and many other mammals, one genotype (cc) prevents any fur color from developing.

70

Red-green color blindness is a sex-linked recessive trait in humans. Two people with normal color vision have a color-blind son. What are the genotypes of the parents?

XRXr and XRY

71

A man who carries an allele of an X-linked gene will pass it on to _____.

all of his daughters.

72

Gene S controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, S, have sharp spines, whereas homozygous recessive sscactuses 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

73

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?

8

74

Which of the following is an example of polygenic inheritance

Skin pigmentation in humans

75

Recombination between linked genes comes about for what reason?

Crossovers between these genes result in chromosomal exchange.

76

What do we mean when we use the terms monohybrid cross and dihybrid cross

  • A dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid cross involves only one.
77

Which of the following is true concerning cancer cells?

When they stop dividing, they do so at random points in the cell cycle; they are not subject to cell cycle controls; and they do not exhibit density-dependent inhibition when growing in culture

78

During meiosis, a defect occurs in a cell that results in the failure of microtubules, spindle fibers, to bind at the kinetochores, a protein structure on chromatids where the spindle fibers attach during cell division to pull sister chromatids apart. Which of the following is the most likely result of such a defect?

The resulting cells will not receive the correct number of chromosomes in the gametes, a condition known as aneuploidy.

79

What is the reason that linked genes are inherited together?

They are located close together on the same chromosom

80

Mendel's second law of independent assortment has its basis in which of the following events of meiosis I?

Alignment of tetrads at the equator.

81

Which of the following is a function of a signal peptide?

To translocate polypeptides across the ER membrane.

82

What is the effect of a nonsense mutation in a gene?

It introduces a premature stop codon into the mRNA.

83

Post-translational modifications of proteins may include the

addition of carbohydrates to form a glycoprotein

84

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.

85

A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein. This is best explained by the fact that:

Many noncoding stretches of nucleotides are present in mRNA

86

Which of the following can be determined directly from x-ray diffraction photographs of crystallized DNA?

The diameter of the helix

87

The following question refers to this table of codons.

What amino acid sequence will be generated based on the following mRNA codon sequence?

5' AUG-UCU-UCG-UUA-UCC-UUG 3'

MET-SER-SER-LEU-SER-LEU

88

Marfan syndrome in humans is caused by an abnormality of the connective tissue protein fibrillin. Patients are usually very tall and thin, with long spindly fingers, curvature of the spine, sometimes weakened arterial walls, and sometimes ocular problems, such as lens dislocation. Which of the following would you conclude about Marfan syndrome from this information?

It is pleiotropic.

89

Which of the following help(s) to hold the DNA strands apart while they are being replicated?

Single-strand binding proteins

90

A frameshift mutation could result from

Either an insertion or a deletion of a base

91

Which of the following nucleotide triplets best represents a codon

A triplet at the opposite end of tRNA from the attachment site of the amino acid

92

During splicing, which molecular component of the spliceosome catalyzes the excision

RNA

93

Which of the following sets of materials are required by both eukaryotes and prokaryotes for replication?

Double-stranded DNA, four kinds of dNTPS, primers, origins

94

What is the function of DNA polymerase III

To add nucleotides to the 3' end of a growing DNA strand

95

A new DNA strand elongates only in the 5' to 3' direction because

DNA polymerase can only add nucleotides to the free 3' end

96

What is the function of topoisomerase

Relieving strain in the DNA ahead of the replication fork

97

The tRNA shown in figure 17.15a of the textbook has its 3' end projecting beyond its 5' end. What will occur at this 3' end

The amino acid binds covalently

98

What is meant by the description "antiparallel" regarding the strands that make up DNA?

The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.

99

Heterochromatin is __________, whereas euchromatin is

Highly condensed, less compact

100

Transcription in eukaryotes requires which of the following in addition to RNA polymerase?

Several transcription factors (TFs)

101

What is the function of the release factor (RF)?

  • It binds to the stop codon in the A site in place of a tRNA.
102

In his transformation experiments, what did Griffith observe?

Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.

103

Researchers found E. coli that had mutation rates one hundred times higher than normal. Which of the following is the most likely cause of these results?

The proofreading mechanism of DNA polymerase was not working properly

104

From your understanding of the cell structure, when the newly made polypeptide is to be secreted from the cell where it has been made, what must occur?

Its signal sequence must lead it to the ER, from which it goes to the Golgi.

105

Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight. This occurs because their cells are impaired in what way

They cannot repair thymine dimers

106

Which of the following does not occur in prokaryotic gene expression, but does in eukaryotic gene expression

A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end.

107

Which of the following investigators was/were responsible for the following discovery? In DNA from any species, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.

Erwin Chargaff

108

There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that

The rules for base pairing between the third base of a codon and tRNA are flexible

109

Which of the following statements is true of linkage?

The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them.

110

Hershey and Chase set out to determine what molecule served as the unit of inheritance. They completed a series of experiments in which E. coli was infected by a T2 virus. Which molecular component of the T2 virus actually ended up inside the cell

DNA

111

At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3' C C T A G G C T G C A A T C C 5' An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?

5' A C G U U A G G 3'

112

An Okazaki fragment has which of the following arrangements?

5' RNA nucleotides, DNA nucleotides 3'

113

To repair a thymine dimer by nucleotide excision repair, in which order do the necessary enzymes act?

Endonuclease, DNA polymerase I, DNA ligase

114

In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after he has removed its 5' cap and poly-A tail. Which of the following would you expect him to find?

The molecule is digested by exonucleases since it is no longer protected at the 5' end.

115

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?

It joins Okazaki fragments together.

116

Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the:

Bonding of the anticodon to the codon and the attachment of amino acids to tRNAs

117

Which of the following would you expect of a eukaryote lacking telomerase

  • A reduction in chromosome length in gametes.