Mastering Biology 8

Which of the following results in a situation in which the chromosome number is either 2n+1 or 2n-1 ?
a) methylation
b) inversion
c) aneuploidy
d) polyploidy
e) gene linkage

c) aneuploidy

One possible result of chromosomal breakage is for a fragment to join a nonhomologous chromosome. What is this alteration called?
a) translocation
b) deletion
c) duplication
d) inversion
e) transversion

a) translocation

Of the following human aneuploidies, which is the one that generally has the most severe impact on the health of the individual?
a) 47, XYY
b) 47, XXY
c) 47, +21
d) 45, X
e) 47, XXX

c) 47, +21

Which of these descriptions of the behavior of chromosomes during meiosis explains Mendel’s law of segregation?
a) The two alleles for each gene separate as homologous chromosomes move apart during anaphase I.
b) Sister chromatids separate during anaphase II.
c) The arrangement of each pair of homologous chromosomes on the metaphase plate during metaphase I is random with respect to the arrangements of other pairs.

a) The two alleles for each gene separate as homologous chromosomes move apart during anaphase I.

Which of these descriptions of the behavior of chromosomes during meiosis explains Mendel’s law of independent assortment?
a) Sister chromatids separate during anaphase II.
b) The two alleles for each gene separate as homologous chromosomes move apart during anaphase I.
c) The arrangement of each pair of homologous chromosomes on the metaphase plate during metaphase I is random with respect to the arrangements of other pairs.

c) The arrangement of each pair of homologous chromosomes on the metaphase plate during metaphase I is random with respect to the arrangements of other pairs.

Select the correct statement(s) about sex determination in animals.
a) In all animals, males have the SRY gene and females lack this gene.
b) In all animals, males are XY and females are XX.
c) The mechanism of sex determination varies with different animal species.

c) The mechanism of sex determination varies with different animal species.

Imagine a human disorder that is inherited as a dominant, X-linked trait. How would the frequency of this disorder vary between males and females?
a) Males and females would display this disorder with equal frequency.
b) Females would display this disorder with greater frequency than males.
c) Males would display this disorder with greater frequency than females.

b) Females would display this disorder with greater frequency than males.

Gregor Mendel set up a dihybrid cross with one pea plant from the parental generation (P) producing round yellow peas and the other pea plant producing wrinkled green peas. The F2 generation included 315 plants producing round yellow peas, 108 with round green peas, 101 with wrinkled yellow peas, and 32 with wrinkled green peas. How would these results have differed if pea shape and pea color had been linked genes, located close together on the same chromosome?
a) The F2 generation would have included a higher percentage of pea plants producing round, yellow peas.
b) The F2 generation would have included a higher percentage of pea plants producing yellow peas.
c) The F2 generation would have included a lower percentage of pea plants producing wrinkled, green peas.

a) The F2 generation would have included a higher percentage of pea plants producing round, yellow peas.

Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?
a) 8%
b) 31%
c) 16%
d) 42%
e) It cannot be determined from the information provided.

a) 8%

______ are the short sections of DNA that are synthesized on the lagging strand of the replicating DNA.

Okazaki fragments

The enzyme that can replicate DNA is called _______.

DNA polymerase

After replication is complete, the new DNA’s, called _________, are identical to each other.

Daughter DNA

During DNA replication, an open section of DNA, in which a DNA polymerase can replicate DNA, is called a __________.

Replication fork

The new DNA strand that grows continuously in the 5′ to 3′ direction is called the _________.

Leading strand

In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.
a) cytosine … uracil
b) uracil … cytosine
c) guanine … adenine
d) cytosine … thymine
e) thymine … cytosine

e) thymine … cytosine

After DNA replication is completed, _____.
a) each of the four DNA strands consists of some old strand parts and some new strand parts
b) there are four double helices
c) each new DNA double helix consists of two new strands
d) each new DNA double helix consists of one old DNA strand and one new DNA strand
e) one DNA double helix consists of two old strands and one DNA double helix consists of two new strands

d) each new DNA double helix consists of one old DNA strand and one new DNA strand

The first step in the replication of DNA is catalyzed by _____.
a) helicase
b) primase
c) ligase
d) DNA polymerase
e) single-strand binding protein

a) helicase

The action of helicase creates _____.
a) DNA fragments and replication forks
b) DNA fragments and replication bubbles
c) primers and DNA fragments
d) primers and replication bubbles
e) replication forks and replication bubbles

e) replication forks and replication bubbles

Why is the new DNA strand complementary to the 3′ to 5′ strands assembled in short segments?
a) only short DNA sequences can extend off the RNA primers
b) DNA polymerase can assemble DNA only in the 5′ to 3′ direction
c) the replication forks block the formation of longer strands
d) it is more efficient than assembling complete new strands
e) DNA polymerase can assemble DNA only in the 3′ to 5′ direction

b) DNA polymerase can assemble DNA only in the 5′ to 3′ direction

The synthesis of a new strand begins with the synthesis of a(n) _____.
a) single-strand binding protein
b) RNA primer complementary to a preexisting DNA strand
c) short pieces of DNA
d) poly(A) tail
e) Okazaki fragment

b) RNA primer complementary to a preexisting DNA strand

An old DNA strand is used as a _____ for the assembly of a new DNA strand.
a) source of nucleotides
b) template
c) complement
d) model
e) primer

b) template

Short segments of newly synthesized DNA are joined into a continuous strand by _____.
a) DNA polymerase
b) helicase
c) primase
d) single-strand binding protein
e) ligase

e) ligase

After DNA replication is completed, _____.
a) each new DNA double helix consists of two new strands
b) one DNA double helix consists of two old strands and one DNA double helix consists of two new strands
c) each of the four DNA strands consists of some old strand parts and some new strand parts
d) there are four double helices
e) each new DNA double helix consists of one old DNA strand and one new DNA strand

e) each new DNA double helix consists of one old DNA strand and one new DNA strand

The first step in the replication of DNA is catalyzed by _____.
a) ligase
b) helicase
c) single-strand binding protein
d) primase
e) DNA polymerase

b) helicase

The action of helicase creates _____.
a) primers and DNA fragments
b) replication forks and replication bubbles
c) primers and replication bubbles
d) DNA fragments and replication bubbles
e) DNA fragments and replication forks

b) replication forks and replication bubbles

Why is the new DNA strand complementary to the 3′ to 5′ strands assembled in short segments?
a) only short DNA sequences can extend off the RNA primers
b) it is more efficient than assembling complete new strands
c) DNA polymerase can assemble DNA only in the 5′ to 3′ direction
d) DNA polymerase can assemble DNA only in the 3′ to 5′ direction
e) the replication forks block the formation of longer strands

c) DNA polymerase can assemble DNA only in the 5′ to 3′ direction

The synthesis of a new strand begins with the synthesis of a(n) _____.
a) short pieces of DNA
b) poly(A) tail
c) RNA primer complementary to a preexisting DNA strand
d) Okazaki fragment
e) single-strand binding protein

c) RNA primer complementary to a preexisting DNA strand

An old DNA strand is used as a _____ for the assembly of a new DNA strand.
a) source of nucleotides
b) model
c) complement
d) template
e) primer

d) template

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

b) single-strand binding proteins

Use the following list of choices for the following question:

I. helicase
II. DNA polymerase III
III. ligase
IV. DNA polymerase I
V. primase

Which of the enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3′ end of Okazaki fragments?
a) I
b) II
c) III
d) IV
e) V

d) IV

Which of the following statements describes the eukaryotic chromosome?
a) The nucleosome is its most basic functional subunit.
b) The number of genes on each chromosome is different in different cell types of an organism.
c) Active transcription occurs on heterochromatin but not euchromatin.
d) It is composed of DNA alone.
e) It consists of a single linear molecule of double-stranded DNA plus proteins.

e) It consists of a single linear molecule of double-stranded DNA plus proteins.

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

a) Histones are positively charged, and DNA is negatively charged.

Which of the following represents the order of increasingly higher levels of organization of chromatin?
a) 30-nm chromatin fiber, nucleosome, looped domain
b) nucleosome, looped domain, 30-nm chromatin fiber
c) nucleosome, 30-nm chromatin fiber, looped domain
d) looped domain, 30-nm chromatin fiber, nucleosome
e) looped domain, nucleosome, 30-nm chromatin fiber

c) nucleosome, 30-nm chromatin fiber, looped domain

You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent
a) leading strands and RNA primers.
b) Okazaki fragments and RNA primers.
c) RNA primers and mitochondrial DNA.
d) leading strands and Okazaki fragments.
e) lagging strands and Okazaki fragments.

d) leading strands and Okazaki fragments

Transcription in eukaryotes requires which of the following in addition to RNA polymerase?
a) ribosomes and tRNA
b) several transcription factors (TFs)
c) aminoacyl synthetase
d) the protein product of the promoter
e) start and stop codons

b) several transcription factors (TFs)

The flow of information in a cell proceeds in what sequence?
a) from DNA to RNA to protein
b) from protein to RNA to DNA
c) from RNA to DNA to protein
d) from DNA to protein to RNA
e) from RNA to protein to DNA

a) from DNA to RNA to protein

A codon consists of _____ bases and specifies which _____ will be inserted into the polypeptide chain.
a) three … nucleotide
b) three … amino acid
c) four … amino acid
d) four … fatty acid
e) two … nucleotide

b) three … amino acid

A particular triplet of bases in the template strand of DNA is 5′ AGT 3′. The corresponding codon for the mRNA transcribed is
a) 3′ ACU 5′.
b) 5′ TCA 3′.
c) 3′ UCA 5′.
d) 3′ UGA 5′.
e) either UCA or TCA, depending on wobble in the first base.

c) 3′ UCA 5′

What is the process called that converts the genetic information stored in DNA to an RNA copy?
a) Replication
b) Translation
c) Translocation
d) Transcription

d) Transcription

DNA does not store the information to synthesize which of the following?
a) Messenger RNA
b) Organelles
c) Proteins
d) DNA

b) Organelles

Transcription begins at a promoter. What is a promoter?
a) A site found on the RNA polymerase
b) A site in DNA that recruits the RNA Polymerase
c) Part of the RNA molecule itself
d) A site where many different proteins will bind
e) A nontranscribed sequence on the DNA

b) A site in DNA that recruits the RNA Polymerase

Which of the following statements best describes the promoter of a protein-coding gene?
a) The promoter is a nontranscribed region of a gene.
b) The promoter is part of the RNA molecule itself.
c) The promoter is a site found on RNA polymerase.
d) The promoter is a site at which only RNA polymerase will bind.

a) The promoter is a nontranscribed region of a gene.

What determines which base is to be added to an RNA strand during transcription?
a) The order of the chemical groups in the backbone of the RNA molecule
b) Base pairing between the two DNA strands
c) Base pairing between the DNA template strand and the RNA nucleotides
d) The previous base

c) Base pairing between the DNA template strand and the RNA nucleotides

Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand?
a) Covalently bound
b) Permanently base-paired
c) Complementary
d) Identical

c) Complementary

What happens to RNA polymerase II after it has completed transcription of a gene?
a) It is degraded.
b) It joins with another RNA polymerase to carry out transcription.
c) It is free to bind to another promoter and begin transcription.
d) It begins transcribing the next gene on the chromosome.

c) It is free to bind to another promoter and begin transcription.