Biology Quiz 4

What does independent assortment actually refer to? A. the separation of alleles in meiosis I. B. the random arrangement of chromosomal tetrads in meiosis I. C. the separation of chromatids in meiosis II. D. the random arrangement of gene loci on a chromosome. E. the fact that any pair of chromatids in a tetrad can cross over.

B. the random arrangement of chromosomal tetrads in meiosis I.

What is the basis behind the difference in how the leading and lagging strands of DNA are synthesized during DNA replication (why is discontinues synthesis of the lagging strand necessary)? a. DNA polymerase III can only add new nucleotides in the 5' to 3' direction b. the origins of replication occur only at the 5' end c. single strand binding proteins can only hold the leading strand open d. DNA ligase only works in the 3' to 5' direction e. prokaryotic chromosomes are circular, eukaryotic chromosomes are linear

a. DNA polymerase III can only add new nucleotides in the 5' to 3' direction

The flow of information in a cell proceeds: a. DNA -> protein -> RNA b. DNA -> RNA -> protein c. RNA -> DNA -> protein d. RNA -> protein -> DNA e. protein -> RNA -> DNA

b. DNA -> RNA -> protein

Which of the following are reasons a cell would replicate its DNA? a. to replace its old worn out DNA b. because its going to divide c. to carry out vital metabolic processes. d. both a and b only

b. because its going to divide

Which of the following is a necessary step from a gene to a protein in a eukaryotic cell, but NOT in a prokaryotic (bacterial) cell? a. the use of messenger RNA b. the removal of introns from pre-mRNA c. the termination of transcription d. the complementary pairing of RNA nucleotides to a DNA template e. the translation of messenger RNA at a ribosome

b. the removal of introns from pre-mRNA

A particular prokaryotic gene contains 90 DNA nucleotides (90 "letters"). Which of the following is the number of amino acids that would be in the polypeptide this gene codes for (hint: think about codons here). a. 3 b. 18 c. 30 d. 90 e. 180

c. 30

The first thing that must be done to begin the replication of DNA is: a. adding complementary nucleotide bases b. making RNA primers c. opening up the double helix d. the fusing together Okazaki fragments e. the removal of thymine dimers

c. opening up the double helix

Before it can begin transcription, the enzyme RNA polymerase needs to bind to DNA at a special site on DNA known as the: a. initiator tRNA b. small ribosomal subunit c. promoter d. operator e. regulatory

c. promoter

An organisms genotype can be thought of as 'instructions' for producing its phenotype(subject, of course, to environmental influences). What is the link between genotype and phenotype (in other words, what are the 'instructions' in the genotype "for", which are then directly involved in the expression of phenotypic traits)? a. nucleic acids b. promoters c. proteins d. genes e. glucose synthesis

c. proteins

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? a. synthesizing RNA primers and attaching them to DNA b. catalyzing the lengthening of telomeres c. unwinding the double helix d. joining Okazaki fragments together e. stabilizing the unwound DNA so it doesnt bind back together

d. joining Okazaki fragments together

When DNA is being replicated, what determines the sequence of the newly synthesized strand? a. which DNA polymerase enzyme is catalyzing the reaction b. the relative amounts of the four nucleotides available to the cell c. the primase enzyme used in the reaction d. the nucleotide sequence of the template strand e. the phosphodiester bonds in the sugar- phosphate backbone

d. the nucleotide sequence of the template strand

Telomeres are special base sequences found at the ends of eukaryotic chromosomes. Which of the following statements is TRUE about telomeres? a. they get longer each time a cell divides b. they are only found in gametes and get removed when an egg is fertilized c. they remain the same length regardless of how many times a cell divides d. they get shorter each time a cell divides e. they contain genes necessary for cellular metabolism

d. they get shorter each time a cell divides

During DNA replication, the enzyme that separates the two DNA strands and "unzips" the double helix is: a. primase b. topoisomerase c. DNA polymerase III d. telomerase e. helicase

e. helicase

Which of the following is TRUE about the process of transcription? a. it takes place in the cytoplasm of a eukaryotic cell b. DNA polymerase III is the major enzyme responsible, and the result is the product of a replicated copy of DNA c. it requires the two ribosomal subunits to be together before it can proceed d. it uses special enzyme called reverse transcriptase to produce a DNA "copy" of RNA e. it results in an RNA molecule that is complimentary to a relatively short stretch of DNA

e. it results in an RNA molecule that is complimentary to a relatively short stretch of DNA

The strands that make up DNA are antiparallel. This means that: a. one strand contains only pyrimidines, the other contains only purines b. the twisting nature of DNA creates a non-parallel arrangement of strands. c. one strand os positively charged, the other is negatively charged d. base pairings create unequal spacing between the two DNA strands e. one strand runs in the 5' to 3' direction, the other strand runs in the 3' to 5' direction

e. one strand runs in the 5' to 3' direction, the other strand runs in the 3' to 5' direction

Which of the following is true of prokaryotic(bacterial) DNA replication, but not of eukaryotic DNA replication? a. each DNA strand serves as a template for a new strand b. the two DNA strands("old" and "new") are complementary c. enzymes are required for replication d. the two DNA strands are antiparallel e. there is a single origin of replication

e. there is a single origin of replication

What is an anticodon part of? A. DNA B. tRNA C. mRNA D. ribosme E. peptidyl transferase enzyme

B. tRNA

Where were the genes in your mitochondria inherited from? A. All came from your mother. B. Half from your mother, half from your father. C. All came from your father.

A. All came from your mother.

In which direction does DNA polymerase III READ a DNA template strand? A. 3' to 5' B. 5' to 3' C. It depends on which strand is being copied.

A. 3' to 5'

Which of the following enzymes "proofreads" each base as it is added to a growing DNA strand? A. DNA polymerase III B. helicase C. ligase D. topoisomerase E. amylase

A. DNA polymerase III

Which of the following is true regarding DNA replication? A. Each daughter cell contains one parental strand and one newly synthesized strand. B. Each daughter cell contains two newly synthesized strands. C. One daughter cell contains two parental strands, the other contains two newly synthesized strands. D. Each daughter cell contains two DNA strands that are made of bits and pieces of old and new strands. E. Each daughter cell contains half the DNA as the parent cell.

A. Each daughter cell contains one parental strand and one newly synthesized strand.

Prokaryotic DNA does not have telomeres. Why not? A. Their DNA is a circular molecule. B. They don't need them because they don't live very long anyway. C. They have enzymes that can spontaneously lengthen shortened DNA. D. They have less DNA than eukaryotes. E. They don't even have DNA, so how could they have telomeres?

A. Their DNA is a circular molecule.

A man who carries an X-linked allele will pass it on to: A. all of his daughters. B. half of his daughters. C. all of his sons. D. half of his sons. E. all of his children.

A. all of his daughters.

Once transcribed, eukaryotic pre-messenger RNA typically undergoes substantial alteration that includes: A. excision of introns. B. fusion into circular forms known as plasmids. C. linkage to histone molecules. D. union with ribosomes. E. fusion with other newly transcribed mRNA.

A. excision of introns.

People with red hair usually have freckles. This can best be explained by: A. linkage. B. reciprocal translocation. C. independent assortment. D. sex-influenced inheritance. E. nondisjunction.

A. linkage.

DNA belongs to which class of biological polymers? A. nucleic acids B. polysaccharides C. proteins D. chromosomes E. triglycerides

A. nucleic acids

Which of the following is NOT needed for DNA replication? A. ribosomes B. nucleotides C. DNA template strands D. enzymes E. all of the above are needed.

A. ribosomes

In eukaryotic cells, transcription cannot begin until: A. the two DNA strands have completely separated and exposed the promoter. B. the appropriate transcription factors have bound to the promoter. C. the 5' caps are removed from the mRNA. D. the DNA introns are removed from the template. E. The repressor protein is off the operator.

B. the appropriate transcription factors have bound to the promoter.

DNA polymerase III adds new nucleotides to a growing strand in which direction? A. 3' to 5' B. 5' to 3' C. It depends on which strand is being copied.

B. 5' to 3'

Which of the following is not directly involved in the process known as translation? A. mRNA B. DNA C. tRNA D. ribosomes E. none of the above are directly involved in translation

B. DNA

DNA polymerase III can only add nucleotides to a pre-existing strand with a free 3' end. During DNA replication, this problem is solved by: A. RNA polymerase B. RNA primers C. single-strand binding proteins D. DNA ligase E. Okazaki fragments

B. RNA primers

What are the coding segments contained within a eukaryotic gene called? A. introns B. exons C. codons D. replicons E. transposons

B. exons

Which of the following enzymes "unzips" the double helix during DNA replication? A. primase B. helicase C. single-strand binding proteins D. DNA polymerase III E. ligase

B. helicase

When a ribosome first attaches to a mRNA molecule, one tRNA binds to the ribosome. The initiator tRNA that recognizes the initiation codon binds to the: A. amino acid (A site) of the ribosome only. B. peptide site (P site) of the ribosome only. C. large ribosomal subunit only. D. second tRNa before attaching to the ribosome. E. Original DNA.

B. peptide site (P site) of the ribosome only.

Which of the following does NOT occur during the termination phase of translation? A. A stop codon moves into the A site. B. The newly formed polypeptide is released. C. A tRNA with the next amino acid enters the P site. D. The two ribosomal subunits separate. E. Translation stops.

C. A tRNA with the next amino acid enters the P site.

Which of the following enzymes are necessary for the removal of an RNA primer, and the repair of the "nick" that results? A. helicase and DNA polymerase I B. DNA polymerase I and primase C. DNA polymerase I and ligase D. primase and ligase E. DNA polymerase I only

C. DNA polymerase I and ligase

Which of the following descriptions best fits the class of molecules known as nucleotides? A. a nitrogenous base and a phosphate group only. B. a nitrogenous base and a five-carbon sugar only. C. a nitrogenous base, a phosphate group, and a five-carbon sugar. D. a five-carbon sugar, a phosphate group, and a purine. E. a pyrimidine, a purine, and a phosphate group.

C. a nitrogenous base, a phosphate group, and a five-carbon sugar.

Where on DNA is the attachment site for RNA polymerase? A. structural gene region B. initiation sequence C. promoter D. operator E. regulator

C. promoter

A recessive allele on the X chromosome is responsible for red-green color blindness in humans. A woman with normal vision whose father is color-blind marries a color-blind male. What is the probability that this couple's son will be color-blind? A. 0% B. 25% C. 50% D. 75% E. 100%

C. 50%

Down's syndrome in humans is an example of: A. polyploidy B. chromosomal inversion C. aneuploidy D. chromosomal deletion E. tetraploidy

C. aneuploidy

DNA is replicated so a cell can: A. produce proteins necessary for its survival. B. replace its old worn-out DNA. C. divide. D. carry out vital metabolic processes. E. all of the above.

C. divide.

A eukaryotic cell lacking telomerase would: A. be unable to take up DNA from the surrounding solution. B. be unable to identify and correct mismatched nucleotides in its daughter DNA strands. C. experience a gradual reduction of chromosome length with each replication cycle. D. have a greater potential to become cancerous. E. incorporate one extra nucleotide for each Okazaki fragment added.

C. experience a gradual reduction of chromosome length with each replication cycle.

A Barr body is normally found in the nucleus of which kind of human cell? A. unfertilized egg cells only B. sperm cells only C. somatic cells of a female only D. somatic cells of a male only E. both male and female somatic cells

C. somatic cells of a female only

When a double-stranded DNA molecule is heated, it denatures into two single-stranded molecules. The reason for this is that: A. the proteins associated with the double helix are denatured and can no longer hold the DNA strands together. B. the heat cause the helix to straighten, breaking the connections between the bases. C. the heat breaks the hydrogen bonds holding the bases together in the center of the molecule but does not affect the covalent bonds of the backbone. D. the heat denatures the bases, preventing them from hydrogen-bonding with each other. E. the heat causes the phosphate groups to ionize, preventing them from hydrogen-bonding to the bases.

C. the heat breaks the hydrogen bonds holding the bases together in the center of the molecule but does not affect the covalent bonds of the backbone.

A fragment of one chromosome breaks off and attaches to a nonhomologous chromosome. This is a(n): A. deletion B. duplication C. translocation D. inversion E. polyploid event

C. translocation

During translation, chain elongation continues until what happens? A. No further amino acids are needed by the cell. B. All tRNAs are empty. C. The polypeptide is long enough. D. A stop codon is reached. E. The ribosomes run off the end of mRNA.

D. A stop codon is reached.

The elongation of the leading strand during DNA synthesis: A. progresses away from the replication fork. B. occurs in the 3' to 5' direction. C. produces Okazaki fragments. D. depends on the action of DNA polymerase III. E. does not require a template strand.

D. depends on the action of DNA polymerase III.

Which of the following represents a similarity between RNA and DNA? A. the presence of a double-stranded helix. B. the presence of uracil. C. the presence of an OH group on the 2' carbon of the sugar. D. nucleotides consisting of a phosphate, sugar, and nitrogenous base. E. repair systems that correct genetic code errors.

D. nucleotides consisting of a phosphate, sugar, and nitrogenous base.

A particular prokaryotic protein is 300 amino acids long. Which of the following is the number of nucleotides in the DNA that codes for this protein? A. 3 B. 100 C. 300 D. 900 E. 1800

D. 900

A cell's DNA is slightly damaged by UV radiation, forming a thymine dimer. How would this damage be repaired? A. It can't. B. By removing just the thymine dimer and replacing it with two new bases. C. By synthesizing an entirely new strand and discarding the old one. D. By removing a small segment which includes the thymine dimer and filling the gap with new nucleotides. E. By producing an entirely new, double-stranded DNA molecule.

D. By removing a small segment which includes the thymine dimer and filling the gap with new nucleotides.

Which of the following is NOT true of a codon? A. It consists of three nucleotides. B. It may code for the same amino acid as another codon does. C. It never codes for more than one amino acid. D. It extends from one end of a transfer RNA molecule. E. It is the basic unit of the genetic code.

D. It extends from one end of a transfer RNA molecule.

Human males exhibit more sex-linked genetic disorders than females. Why? A. Males have more chromosomes than females, so there is a greater chance of their receiving a mutant allele. B. Male hormones cause the expression of most sex-linked disorders. C. Many sex-linked disorders are carried on the Y chromosome. D. Males have only one X chromosome, so any male receiving a mutant allele will express the trait. E. Females are just lucky.

D. Males have only one X chromosome, so any male receiving a mutant allele will express the trait.

There is good evidence for linkage when: A. two genes occur together in the same gamete. B. a gene is associated with a specific phenotype. C. two genes work together to control a specific characteristic. D. genes do not segregate independently during meiosis. E. two characteristics are caused by a single gene.

D. genes do not segregate independently during meiosis.

The information carried by DNA is in its: A. complementary pairing of bases. B. different five-carbon sugars. C. sugar-phosphate backbone. D. sequence of bases. E. side groups of nitrogenous bases.

D. sequence of bases.

Vermilion eyes is a sex-linked recessive characteristic in fruit flies. If a female having vermilion eyes is crossed with a wild-type male, what proportion of the F1 males will have vermilion eyes? A. None B. 25% C. 50% D. 75% E. 100%

E. 100%

As a ribosome translocates along an mRNA molecule by one codon, which of the following occurs? A. The tRNA that was in the A site moves into the P site. B. The tRNA that was in the P site moves into the A site. C. The tRNA that was in the P site departs from the ribosome. D. The tRNA that was in the A site departs from the ribosome. E. Both a and c are correct.

E. Both a and c are correct.

Which of the following is true of RNA but NOT DNA? A. Consists of nucleotide monomers. B. Contains the purines adenine and guanine. C. Contains the pyrimidine cytosine. D. Exists as a double-helix. E. Is a single-stranded molecule.

E. Is a single-stranded molecule.

The "problem" of replicating the lagging strand during DNA A. replication forks. B. helicases. C. base pairing. D. DNA ligase. E. Okazaki fragments.

E. Okazaki fragments.

Which of the following mutations would be most likely to have a harmful effect on an organism? A. a base-pair substitution. B. a deletion of three bases near the middle of a gene. C. a single base deletion near the middle of an intron. D. a single base deletion close to the end of the coding sequence. E. a single base insertion near the start of the coding sequence.

E. a single base insertion near the start of the coding sequence.

A frameshift mutation could result from: A. a base insertion only. B. a base deletion only. C. a base substitution only. D. deletion of three consecutive bases. E. either an insertion or a deletion of a base.

E. either an insertion or a deletion of a base.

The frequency of crossing over between any two linked genes is: A. more likely if they are recessive. B. difficult to predict. C. determined by their relative dominance. D. the same as if they were not linked. E. proportional to the distance between them.

E. proportional to the distance between them.

Prokaryotic DNA replication begins simultaneously at many origins of replication. True False

False

The sex that produces two kinds of gametes is the homogametic sex. True False

False