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Kocher, Thomas. University of MD, College Park. Genetics Final Exam Review Fall 2016

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Genetics Final Exam

Question 22 of 112 Question 1 of 112

1

Fill the blank space to complete the text.

The full chemical name of DNA is .

Explanation

Question 20 of 112 Question 2 of 112

1

Fill the blank space to complete the text.

The protein, , is needed to lay down a segment of RNA complementary to the DNA before replication can begin.

Explanation

Question 62 of 112 Question 3 of 112

1

Fill the blank space to complete the text.

An origin of replication generally has (how many?) replication forks.

Explanation

Question 49 of 112 Question 4 of 112

1

Fill the blank space to complete the text.

The discontinuous lagging strand on a replication fork consists of that are later ligated together to form one strand of DNA.

Explanation

Question 56 of 112 Question 5 of 112

1

Fill the blank space to complete the text.

The E. coli chromosome contains (how many?) origin(s) of replication?

Explanation

Question 51 of 112 Question 6 of 112

1

Fill the blank space to complete the text.

A prokaryote lacks a membrane.

Explanation

Question 107 of 112 Question 7 of 112

1

Fill the blank space to complete the text.

Recombination is probably always initiated by of DNA.

Explanation

Question 78 of 112 Question 8 of 112

1

Fill the blank space to complete the text.

The strand is synthesized continuously during DNA replication.

Explanation

Question 5 of 112 Question 9 of 112

1

Fill the blank space to complete the text.

A enzyme recognizes a specific DNA sequence and is able to cleave the DNA generating either “blunt” or “sticky” ends of the DNA.

Explanation

Question 27 of 112 Question 10 of 112

1

Fill the blank space to complete the text.

A virus that infects bacterial cells is called a .

Explanation

Question 67 of 112 Question 11 of 112

1

Fill the blank space to complete the text.

The genetic material of some viruses such as pi X 174 and M13 is .

Explanation

Question 45 of 112 Question 12 of 112

1

Fill the blank space to complete the text.

The genetic material of the viruses that cause polio and AIDS is .

Explanation

Question 105 of 112 Question 13 of 112

1

Fill the blank space to complete the text.

Topoisomerase supercoils by nicking the DNA.

Explanation

Question 66 of 112 Question 14 of 112

1

Fill the blank space to complete the text.

In E. coli, recombination begins at sites where recBCD nicks and displaces a strand.

Explanation

Question 73 of 112 Question 15 of 112

1

Which of the following is not true of DNA?

Select one of the following:

  • It is found in cell nuclei.

  • It contains proteins.

  • It contains phosphate.

  • It is acidic.

  • It contains deoxyribose.

Explanation

Question 52 of 112 Question 16 of 112

1

The molecule of heredity is:

Select one of the following:

  • protein

  • none of the above

  • DNA

  • RNA

  • carbohydrate

Explanation

Question 102 of 112 Question 17 of 112

1

The four subunits which compose DNA are called:

Select one of the following:

  • polymers

  • phosphodiesters

  • nucleosides

  • proteins

  • nucleotides

Explanation

Question 86 of 112 Question 18 of 112

1

DNA is localized mainly in the

Select one of the following:

  • chromosomes

  • cell membrane

  • vacuoles

  • endoplasmic reticulum

  • None of the above

Explanation

Question 53 of 112 Question 19 of 112

1

Each nucleotide of DNA is made up of:

Select one of the following:

  • a phosphate

  • a nitrogenous base

  • a deoxyribose sugar

  • A and B only

  • All of the above

Explanation

Question 103 of 112 Question 20 of 112

1

The polarity of DNA synthesis is:

Select one of the following:

  • 3' → 5'

  • 5' → 3'

  • 5' → 2'

  • 2' → 5'

  • none of the above

Explanation

Question 12 of 112 Question 21 of 112

1

In the Hershey and Chase experiment designed to determine the molecule of heredity, what was radiolabeled with 35-S?

Select one of the following:

  • none of the above

  • RNA

  • rRNA

  • protein

  • DNA

Explanation

Question 71 of 112 Question 22 of 112

1

The ratio of _____ is 1:1.

Select one of the following:

  • none of the above

  • cytosine to adenine

  • adenine to thymine

  • uracil to cytosine

  • guanine to adenine

Explanation

Question 39 of 112 Question 23 of 112

1

X-ray data showed that the spacing between repeating units along the axis of the DNA helix is:

Select one of the following:

  • 3.4 angstroms.

  • none of the above

  • 34 angstroms.

  • 20 angstroms.

  • 2.0 angstroms.

Explanation

Question 58 of 112 Question 24 of 112

1

X-ray data showed that the DNA helix undergoes one complete turn every:

Select one of the following:

  • none of the above

  • 3.4 angstroms.

  • 20 angstroms.

  • 34 angstroms.

  • 2.0 angstroms.

Explanation

Question 6 of 112 Question 25 of 112

1

________ bonds are responsible for the chemical affinity between A and T (or G and C) nucleotides.

Select one of the following:

  • none of the above

  • Ionic

  • Electro-ionic

  • Covalent

  • Hydrogen

Explanation

Question 104 of 112 Question 26 of 112

1

_______ -form DNA spirals to the right and is the major form of naturally occurring DNA molecules.

Select one of the following:

  • Y

  • B

  • A

  • D

  • Z

Explanation

Question 29 of 112 Question 27 of 112

1

The nucleotide that is present in RNA but not DNA is:

Select one of the following:

  • cytosine

  • adenine

  • thymine

  • guanosine

  • uracil

Explanation

Question 40 of 112 Question 28 of 112

1

DNA replication occurs through a _________process.

Select one of the following:

  • dispersive

  • transferal

  • conservative

  • semiconervative

  • none of the above

Explanation

Question 97 of 112 Question 29 of 112

1

During complementary base pairing, enzymes join the base's nucleotide to the preceding nucleotide by a __________bond.

Select one of the following:

  • Ionic

  • None of the above

  • Electrostatic

  • Hydrogen

  • Phosphodiester

Explanation

Question 70 of 112 Question 30 of 112

1

During early interphase the state of the DNA can be described as:

Select one of the following:

  • a single continuous linear double helix.

  • single-stranded DNA.

  • None of the above

  • a double helix replicated conservatively.

  • a double helix replicated semiconservatively.

Explanation

Question 41 of 112 Question 31 of 112

1

During the S phase of interphase, the state of the DNA can be described as:

Select one of the following:

  • a double helix replicated conservatively.

  • a single continuous linear double helix.

  • a double helix replicated semiconservatively.

  • a triple helix replicated semiconservatively.

  • None of the above

Explanation

Question 80 of 112 Question 32 of 112

1

The step in DNA replication in which the replication proteins open up the double helix and prepare for complementary base pairing is called:

Select one of the following:

  • Translation

  • Translocation

  • Elongation

  • Initiation

  • Termination

Explanation

Question 61 of 112 Question 33 of 112

1

The step in DNA replication in which the proteins connect the correct sequence of nucleotides into a continuous new strand is called:

Select one of the following:

  • Termination

  • Elongation

  • Initiation

  • Translation

  • Translocation

Explanation

Question 26 of 112 Question 34 of 112

1

The step in DNA replication in which two replication forks moving in opposite directions may meet is called:

Select one of the following:

  • Termination

  • Intiation

  • Translocation

  • Elongation

  • Translation

Explanation

Question 75 of 112 Question 35 of 112

1

The group of enzymes able to relax supercoils in DNA is called:

Select one of the following:

  • Telomeres

  • Helicases

  • Topoisomerases

  • Primases

  • Ligases

Explanation

Question 33 of 112 Question 36 of 112

1

How many replication forks depart from an origin of replication?

Select one of the following:

  • none of the above

  • three

  • four

  • two

  • one

Explanation

Question 54 of 112 Question 37 of 112

1

The protein that progressively unwinds DNA ahead of each replication fork is called:

Select one of the following:

  • Topoisomerase

  • Helicase

  • Telomerase

  • Ligase

  • Primase

Explanation

Question 8 of 112 Question 38 of 112

1

In eukaryotic cells, replication proceeds from ____ origin(s) of replication.

Select one of the following:

  • two

  • one

  • several

  • many

  • no

Explanation

Question 74 of 112 Question 39 of 112

1

Eukaryotic chromosomes have evolved special structures at the ends of chromosomes to ensure the replication of the two ends of linear chromosomes. These structures are

Select one of the following:

  • ligases

  • methylases

  • capping proteins

  • telomerases

  • single-stranded binding proteins

Explanation

Question 44 of 112 Question 40 of 112

1

Which of the following is NOT involved in ensuring the accuracy of a cell's genetic information?

Select one of the following:

  • redundancy

  • repair enzymes

  • DNA polymerase proofreading mechanism

  • Restriction endonucleases

  • precision of replication machinery

Explanation

Question 79 of 112 Question 41 of 112

1

The process of _________ is extremely important in generating genetic diversity.

Select one of the following:

  • Transformation

  • Transcription

  • None of the above

  • Recombination

  • Translation

Explanation

Question 84 of 112 Question 42 of 112

1

Any deviation from the expected 2:2 segregation of parental alleles that results from recombination is known as:

Select one of the following:

  • DNA replication

  • Crossing over

  • Allelic exchange

  • Recombination

  • Gene conversion

Explanation

Question 23 of 112 Question 43 of 112

1

Recombination involves the breakage and reunion of DNA molecules from:

Select one of the following:

  • homologous sister chromatids

  • homologous nonsister chromatids

  • heterologous sister chromatids

  • heterologous nonsister chromatids

  • None of the above

Explanation

Question 28 of 112 Question 44 of 112

1

The nicking of DNA that initiates recombination during mitosis may be due to all but:

Select one of the following:

  • Chemical change

  • Physical change

  • X-rays

  • instruction from normal cell-cycle program

  • Radiation

Explanation

Question 9 of 112 Question 45 of 112

1

What radiolabeled substance did Hershey and Chase use to label the protein component of the bacteriophage in their study to determine whether protein or DNA was necessary for phage production?

Select one of the following:

  • phosphorous

  • nitrogen

  • sulfur

  • carbon

  • iodide

Explanation

Question 47 of 112 Question 46 of 112

1

If 35% of the bases in a region of the mouse genome are cytosine, what percentage in that region are adenine?

Select one of the following:

  • none of the above

  • 15%

  • 35%

  • 30%

  • 20%

Explanation

Question 15 of 112 Question 47 of 112

1

The complementary sequence of 5' AATTCGCTTA 3' is:

Select one of the following:

  • 5' TAACGCTTAA 3'

  • 5' TAAGCGAATT 3'

  • 3' AATTCGCTTA 5'

  • 5' AATTCGCTTA 3'

  • 3' TAAGCGAATT 5'

Explanation

Question 30 of 112 Question 48 of 112

1

Two strains of S. cerevisae (yeast) are crossed. One has the genotype ABC and the other abc. Five sets of the resultant tetrads are noted below. In which set did a gene conversion event occur?

Select one of the following:

  • aBc, aBc, AbC, AbC

  • abc, abc, ABC, ABC

  • Abc, Abc, aBC, aBC

  • abC, abc, ABc, ABC

  • abc, aBc, AbC, aBC

Explanation

Question 3 of 112 Question 49 of 112

1

Recombination occurs during meiotic ________.

Select one of the following:

  • none of the above

  • interphase

  • prophase

  • metaphase

  • anaphase

Explanation

Question 37 of 112 Question 50 of 112

1

Without __________ regions on the DNA during recombination, gene conversion could not occur.

Select one of the following:

  • homotriplex

  • heteroduplex

  • homoduplex

  • none of the above

  • heterotriplex

Explanation

Question 31 of 112 Question 51 of 112

1

Occasionally, a loss of function mutation may occur in the telomerase enzyme in a cell. What is likely to be the result of this mutation on the DNA in the cell over the the course of several rounds of mitosis?

Select one of the following:

  • chromosome length will gradually increase

  • chromosome length will gradually decrease

  • chromosomes will fail to dissociate after replication

  • chromosome length will stay constant

  • none of the above

Explanation

Question 110 of 112 Question 52 of 112

1

Bacterial DNA is resistant to degradation by its own restriction enzymes through the protection of:

Select one of the following:

  • Primases

  • Topoisomerases

  • Ligases

  • Recombinases

  • Methylases

Explanation

Question 82 of 112 Question 53 of 112

1

Hershey and Chase relied on ________ to physically separate the infected bacterial cells from the phage ghosts.

Select one of the following:

  • radioactivity

  • gel filtration

  • ion exchange

  • none of the above

  • centrifugation

Explanation

Question 83 of 112 Question 54 of 112

1

Meselson and Stahl relied on equilibrium density gradient centrifugation in a _______ solution to resolve the DNA containing 14N from the DNA containing 15-N.

Select one of the following:

  • sodium acetate

  • calcium chloride

  • radiolabeled phosphate

  • cesium chloride

  • radiolabeled nitrogen

Explanation

Question 43 of 112 Question 55 of 112

1

Fill the blank spaces to complete the text.

Match the scientist with their contribution to understanding more about DNA
a. early recombination models
b. transformation
c. semiconservative replication
d. x-ray structure of DNA
e. revised recombination models
f. basic structure of DNA
g. DNA = molecule of heredity
h. discovery of “nuclein”
i. nucleotide ratios in DNA
j. famous phage blender experiment

55. Watson and Crick

56. Chargaff

57. Franklin and Wilkins

58. Griffith

59. Hershey and Chase

60. Miescher

61. Meselson and Stahl

62. Holliday

63. Meselson and Radding

64. Avery, MacLeod and McCarty

Explanation

Question 55 of 112 Question 56 of 112

1

Click on each orange point and write the correct answer.

Diagram Matching (Match the region or item on the diagram with the correct term from the list below)

-lagging strand

-leading strand

-origin

-RNA primer

-Okazaki fragment

-helicase

-polymerase

1
2
3
4
5
6
7

Explanation

Question 96 of 112 Question 57 of 112

1

A phosphodiester bond joins one nucleotide together in the DNA polymer.

Select one of the following:

  • True
  • False

Explanation

Question 65 of 112 Question 58 of 112

1

Prokaryotes have a circular chromosome surrounded by a nuclear membrane.

Select one of the following:

  • True
  • False

Explanation

Question 95 of 112 Question 59 of 112

1

Transformation in bacteria results from the uptake of foreign DNA.

Select one of the following:

  • True
  • False

Explanation

Question 7 of 112 Question 60 of 112

1

DNA is highly negatively charged throughout the molecule and therefore has no

Select one of the following:

  • True
  • False

Explanation

Question 109 of 112 Question 61 of 112

1

A region of DNA 100 bp in length has the potential to be represented by 4100 unique sequences.

Select one of the following:

  • True
  • False

Explanation

Question 14 of 112 Question 62 of 112

1

Viruses use only DNA as their genetic material.

Select one of the following:

  • True
  • False

Explanation

Question 24 of 112 Question 63 of 112

1

Restriction enzymes are molecular weapons which cut DNA that bacteria use in their fight to protect themselves from DNA viruses.

Select one of the following:

  • True
  • False

Explanation

Question 13 of 112 Question 64 of 112

1

Human DNA is replicated in a conservative manner.

Select one of the following:

  • True
  • False

Explanation

Question 63 of 112 Question 65 of 112

1

In DNA replication, new DNA is produced in a continuous bi-directional fashion.

Select one of the following:

  • True
  • False

Explanation

Question 76 of 112 Question 66 of 112

1

DNA topoisomerase supercoils DNA to get it out of the way of DNA polymerase.

Select one of the following:

  • True
  • False

Explanation

Question 59 of 112 Question 67 of 112

1

Accuracy of replication is enhanced by the redundancy of DNA, enzymatic repair of damaged DNA and the remarkable precision of the cellular replication machinery.

Select one of the following:

  • True
  • False

Explanation

Question 72 of 112 Question 68 of 112

1

A 2:2 segregation of parental alleles is known as gene conversion.

Select one of the following:

  • True
  • False

Explanation

Question 34 of 112 Question 69 of 112

1

Recombination events are limited to only “hot spots” along a chromosome.

Select one of the following:

  • True
  • False

Explanation

Question 50 of 112 Question 70 of 112

1

Gene conversion in which a small segment of information from one homologous chromosome transfers to the other can give rise to an unequal yield of two different alleles.

Select one of the following:

  • True
  • False

Explanation

Question 93 of 112 Question 71 of 112

1

Alternative resolutions of the Holliday intermediate are responsible for whether or not crossing over or gene conversion occurs.

Select one of the following:

  • True
  • False

Explanation

Question 64 of 112 Question 72 of 112

1

Fill the blank space to complete the text.

Genes that “travel” together from one generation to the next more often than not exhibit .

Explanation

Question 46 of 112 Question 73 of 112

1

Fill the blank space to complete the text.

A probability test that measures “goodness of fit” between observed and predicted results is a test.

Explanation

Question 99 of 112 Question 74 of 112

1

Fill the blank space to complete the text.

A hypothesis that predicts no linkage between genes is called the hypothesis.

Explanation

Question 32 of 112 Question 75 of 112

1

Fill the blank space to complete the text.

Genes that can serve points of reference on a chromosome are useful as genetic markers while cytologically visible abnormalities that also make it possible to keep track of chromosomes are called markers.

Explanation

Question 98 of 112 Question 76 of 112

1

Fill the blank space to complete the text.

The movement of chiasmata toward the end of a chromosome is called .

Explanation

Question 11 of 112 Question 77 of 112

1

Fill the blank space to complete the text.

One percentage point of recombination, or recombination frequency, is a unit of measure called either centimorgan or .

Explanation

Question 18 of 112 Question 78 of 112

1

Fill the blank space to complete the text.

Crossovers do not occur independently and the occurrence of one crossover reduces the likelihood of another occurring elsewhere on the chromosome this is called .

Explanation

Question 88 of 112 Question 79 of 112

1

Fill the blank space to complete the text.

A tetrad that contains four recombinant class haploid cells is known as a ditype.

Explanation

Question 87 of 112 Question 80 of 112

1

Fill the blank space to complete the text.

A tetrad that carries four kinds of haploid cells: two different parental and two different recombinant class spores is referred to as .

Explanation

Question 68 of 112 Question 81 of 112

1

Fill the blank space to complete the text.

Mistakes in mitosis during development often result in organisms containing tissues of different genotypes.

Explanation

Question 108 of 112 Question 82 of 112

1

The R/r and S/s genes are linked and 10 map units apart. In the cross Rs/rS  rs/rs what fraction of the progeny will be RS/rs?

Select one of the following:

  • 5%

  • 45%

  • 25%

  • 10%

  • 40%

Explanation

Question 89 of 112 Question 83 of 112

1

If the map distance between genes A and B is 10 map units and the map distance between genes B and C is 25 map units, what is the map distance between genes A and C?

Select one of the following:

  • Either 15 map units or 35 map units, depending on the order of the genes

  • 15 map units

  • The map distance between A and C can not be predicted from this data

  • 35 map units

Explanation

Question 111 of 112 Question 84 of 112

1

In Drosophila, singed bristles (sn) and cut wings (ct) are both caused by recessive, X-linked alleles. The wild type alleles (sn+ and ct+) are responsible for straight bristles and intact wings, respectively. A female homozygous for sn and ct+ is crossed to a sn+ct male. The F1 flies are interbred. The F2 males are distributed as follows:
sn ct 13
sn ct+ 36
sn+ ct 39
sn+ ct+ 12
What is the map distance between sn and ct?

Select one of the following:

  • 12 m.u.

  • 50 m.u.

  • 75 m.u.

  • 25 m.u.

  • 13 m.u.

Explanation

Question 90 of 112 Question 85 of 112

1

What is the value of X2 for a test of the hypothesis that the sn and car genes are unlinked?

Select one of the following:

  • 0.4

  • 0.5

  • 1.0

  • 2.0

  • 20

Explanation

Question 1 of 112 Question 86 of 112

1

What is the p value from this test? (Pick the most accurate choice.)

Select one of the following:

  • p < 0.1

  • p < 0.01

  • p > 0.5

  • p < 0.05

  • 0.5 > p > 0.1

Explanation

Question 60 of 112 Question 87 of 112

1

Suppose the L and M genes are on the same chromosome but separated by 100 map units. What fraction of the progeny from the cross LM/lm x lm/lm would be Lm/lm?

Select one of the following:

  • 100%

  • 25%

  • 75%

  • 10%

  • 50%

Explanation

Question 57 of 112 Question 88 of 112

1

The pairwise map distances for four linked genes are as follows: A-B = 22 m.u., B-C = 7 m.u., C-D = 9 m.u., B-D = 2 m.u., A-D = 20 m.u., A-C = 29 m.u. What is the order of these four genes?

Select one of the following:

  • ABDC

  • ABCD

  • BADC

  • CADB

  • ADBC

Explanation

Question 21 of 112 Question 89 of 112

1

The zipper-like connection between paired homologs in early prophase is known as a:

Select one of the following:

  • chiasma

  • none of the above

  • synaptic junction

  • synaptomnemal complex

  • spindle fiber

Explanation

Question 2 of 112 Question 90 of 112

1

The measured distance between genes D and E in a two point test cross is 50 map units. What does this mean in physical terms?

Select one of the following:

  • D and E are on different pairs of chromosomes.

  • either A or C

  • either A or B

  • D and E are linked and at least 50 map units apart.

  • D and E are linked and exactly 50 map units apart.

Explanation

Question 94 of 112 Question 91 of 112

1

Suppose an individual is heterozygous for a pair of alleles (e.g. A/a). Under what conditions would a crossover in a somatic cell of this individual lead to a clone of cells homozygous for a? (Pick the most precise answer.)

Select one of the following:

  • The crossover would have to occur between the A locus and the centromere and involve two homologous (non-sister) chromatids.

  • The crossover would have to occur on the same chromosome as the A locus and involve two homologous (non-sister) chromatids.

  • The crossover would have to occur on the same chromosome arm as the A locus and involve two homologous (non-sister) chromatids.

  • The crossover would have to occur between the A locus and the centromere and involve two sister chromatids (not homologous) chromatids.

  • The crossover would have to occur between the A locus and the end of the chromosome and involve two homologous (non-sister) chromatids.

Explanation

Question 16 of 112 Question 92 of 112

1

Suppose an individual is heterozygous for two linked pairs of alleles on the same chromosome arm, Ab/aB such that the A locus is closer to the centromere than the B locus. Under what conditions would a crossover in a somatic cell generate a twin spot, i.e. two adjacent clones of cells, one clone homozygous for a and the other clone homozygous for b?

Select one of the following:

  • No crossover in a somatic cell could generate a twin spot.

  • The crossover would have to occur between the A locus and the centromere locus and involve two homologous (non-sister) chromatids.

  • The crossover would have to occur between the A locus and the B locus locus and involve two homologous (non-sister) chromatids.

  • A double crossover would have to occur, with one crossover between the A locus and the centromere and a second crossover between the A and B loci locus and both crossovers would have to involve two homologous (non-sister) chromatids.

  • The crossover would have to occur between the B locus and the end of the chromosome locus and involve two homologous (non-sister) chromatids.

Explanation

Question 17 of 112 Question 93 of 112

1

What happens physically during the process of crossing over?

Select one of the following:

  • It is not known what occurs during crossing over.

  • Two homologous chromatids break and rejoin at random sites along the chromosome.

  • Two homologous chromatids break and rejoin at precisely the same site along the chromosome so that there is no loss or gain of material on either product.

  • The genetic information on one chromatid is replaced by copying genetic information from a homologous chromatid without there being any physical exchange between the chromosomes.

Explanation

Question 10 of 112 Question 94 of 112

1

Here is a list of events during meiosis I. It is not in the correct order.
A) Homologous chromosomes are roughly aligned but not physically linked.
B) Homologous chromosomes segregate to opposite poles.
C) Homologous chromosomes are linked by synaptonemal complexes.
D) Homologous chromosomes are linked by chiasmata.
E) Chromosomes replicate.
What is the correct order of these events?

Select one of the following:

  • EACDB

  • ACDBE

  • EADCB

  • CDABE

  • AECDB

Explanation

Question 85 of 112 Question 95 of 112

1

Some of the larger human chromosomes typically contain multiple chiasmata during meiotic prophase. If you were to carefully study the distribution of these chiasmata, what would you find?

Select one of the following:

  • Chiasmata are spaced along a chromosome arm more regularly than would be expected by chance.

  • A single chromosome pair always has the same number of chiasmata in every meiotic cell.

  • All chromosome pairs have the same number of chiasmata.

  • Chiasmata are spaced more irregularly along a chromosome arm than would be expected by chance.

  • Chiasmata are randomly distributed along chromosomes.

Explanation

Question 91 of 112 Question 96 of 112

1

Recombination due to crossing over occurs only rarely in mitosis.

Select one of the following:

  • True
  • False

Explanation

Question 19 of 112 Question 97 of 112

1

When considering the chi-square test, a p-value of 0.05 is often considered significant but is actually an arbitrary assignment of significance.

Select one of the following:

  • True
  • False

Explanation

Question 25 of 112 Question 98 of 112

1

Chiasmata are structures of cross over between sister chromatids of homologous chromosomes.

Select one of the following:

  • True
  • False

Explanation

Question 69 of 112 Question 99 of 112

1

Chiasmata can be seen through a light microscope and are sites of recombination.

Select one of the following:

  • True
  • False

Explanation

Question 4 of 112 Question 100 of 112

1

Three-point crosses are more tedious and less accurate than two-point crosses.

Select one of the following:

  • True
  • False

Explanation

Question 48 of 112 Question 101 of 112

1

Chromosomal interference is not uniform and may significantly vary within a region of a single chromosome.

Select one of the following:

  • True
  • False

Explanation

Question 77 of 112 Question 102 of 112

1

Genetic mapping distance calculated for a chromosome is directly related to physical distance along that chromosome.

Select one of the following:

  • True
  • False

Explanation

Question 36 of 112 Question 103 of 112

1

Genes chained together by linkage relationships are known collectively as a linkage group.

Select one of the following:

  • True
  • False

Explanation

Question 112 of 112 Question 104 of 112

1

Ascospores are haploid cells that can germinate, replicate by mitosis, and survive as haploid individuals.

Select one of the following:

  • True
  • False

Explanation

Question 35 of 112 Question 105 of 112

1

The Hardy-Weinberg equilibrium principle yields which of the following conclusions?

Select one of the following:

  • If the allele frequencies in a population are given by p and q, the genotype frequencies are given by p2, 2 pq and q2.

  • The allele frequencies in a population will not change over time.

  • The first and second choices are correct.

  • If the allele frequencies in a population are given by p and q, the genotype frequencies are given by p2 and q2. d. The first and third answers are correct.

Explanation

Question 38 of 112 Question 106 of 112

1

The HIV epidemic is unlikely to lead to an increase in the CCR5 delta-32 allele over the short term because ___________________.

Select one of the following:

  • In populations with high selection pressure, the allele frequency is low.

  • The first and second choices are correct.

  • the allele is recessive and deleterious.

  • in populations with a high frequency of the allele, selection pressure is relatively low.

Explanation

Question 101 of 112 Question 107 of 112

1

Over the long term, selection favoring the rare phenotype in a polymorphic population (i.e., negative frequency dependent selection), will __________ genetic diversity in the population.

Select one of the following:

  • increase

  • decrease

  • maintain

Explanation

Question 42 of 112 Question 108 of 112

1

Which of these statements is true for underdominance?

Select one of the following:

  • Allele frequencies may initially hover at an unstable equilibrium, but will eventually change.

  • Allele frequencies will tend to move towards fixation or loss.

  • Allele frequencies will tend to move toward a stable equilibrium.

Explanation

Question 92 of 112 Question 109 of 112

1

When selection acts against a recessive allele that is initially at high frequency in a population, ____________________.

Select one of the following:

  • the frequency of the allele will be unchanged;

  • the allele declines in frequency until it is eliminated.

  • the frequency of the allele will stay high for a long time, then decline slowly.

  • the population will remain in Hardy-Weinberg equilibrium. the frequency of the allele will decline rapidly, and then stabilize at very low frequency.

Explanation

Question 106 of 112 Question 110 of 112

1

When selection favors heterozygotes over homozygotes, ____________________.

Select one of the following:

  • both alleles are maintained at a frequency different from that predicted by Hardy-Weinberg principles based on the strength of selection against the recessive allele.

  • The first two choices are both correct.

  • The first three choices are correct.

  • the selective advantage enjoyed by the deleterious allele in the heterozygote exactly

  • genetic diversity in the population can be maintained indefinitely, in spite of selection acting against the allele. balances the selective disadvantage suffered by homozygous recessive individuals.

Explanation

Question 100 of 112 Question 111 of 112

1

When selection favors homozygotes over heterozygotes ____________________.

Select one of the following:

  • the genetic variation within a population is maintained over time

  • genetic variation among populations will decline.

  • both alleles are maintained in the population at frequencies different from those predicted by Hardy-Weinberg principles.

  • the most common outcome will be that the most common allele will become fixed (will increase to a frequency of 1) in the population.

Explanation

Question 81 of 112 Question 112 of 112

1

Pier and his colleagues have suggested that cystic fibrosis is maintained at relatively high levels in people of European ancestry because of heterozygote superiority; specifically, he proposposes that heterozygotes are more resistant to typhoid fever than are the dominant homozygotes. Evidence in favor of this hypothesis includes which of the following findings?

Select one of the following:

  • Salmonella typhi bacteria manipulate their host cells, causing them to express more CFTR protein on their membranes.

  • All of the choices above are correct.

  • The mutation rate for new loss-of-function mutations in the CFTR gene is too low for the prevalence of the disease to be explained by mutation/selection balance.

  • Pier and his colleagues have found, in 11 European countries, an association between the severity of typhoid fever outbreaks and the frequency of the delta-F508 allele (the most common loss-of-function mutation) a generation later.

  • Pier et al. engineered cells homozygous for functional CFTR alleles, homozygous for a common loss-of-function allele, and heterozygous for the two. The loss-of-function homozygotes were virtually impervious to invasion by typhoid fever-causing bacteria; heterozygotes were more vulnerable, but accumulated 86% fewer bacteria than did the dominant homozygotes.

Explanation

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