iclicker / blackboard questions (exam 2)

Question 1

which of the following statements is incorrect?

a) All cells in a body have the same genes.
b) All cells in a body express the same genes.
c) All cells in a body have the same proteins
d) A and C.
e) All of the above.

Answer 1

a) All cells in a body have the same genes.

Question 2

Most chemical reactions in a cell are performed by:

a) nucleic acids
b) lipids
c) amino acids
d) proteins
e) carbohydrates

Answer 2

d) proteins

Question 3

Which of the following statements is correct?

a) microRNAs bind DNA and block transcription.
b) microRNAs bind ribosomal RNA and block translation.
c) microRNAs bind mRNA and block translation
d) A and C.
e) All of the above.

Answer 3

c) microRNAs bind mRNA and block translation

Question 4

Chromosome inversions are important to evolution because they result in:

a) new genes.
b) rapid speciation.
c) new alleles.
d) supergenes.
e) all of the above.

Answer 4

d) supergenes

Question 5

Compute the genotype frequencies and allele frequencies for the wild type (+) and mutant type (Δ32) alleles for the CCR5 gene in the population with the following genotype distribution:
+/+ – 441 +/Δ32 – 81 Δ32/Δ32 – 18
What is the allele frequency of the wild type (+)?
a) 0.09
b) 0.11
c) 0.48
d) 0.89
e) 0.97

Answer 5

d) 0.89

Question 6

Which of the following is evidence that the internal structure of the
forelimb is homologous between birds and bats?
a) Both have forelimbs adapted for flight.
b) The same bone structure is present in Tiktaalik, the nearest sister taxon to tetrapods, indicating that it was shared by the common ancestor of tetrapods.
c) There are many differences in the wings of birds and bats, such as feathers and reduction of digits in birds and a skin membrane supported by digits in bats.
d) The forelimbs of birds and bats are in no way homologous.
e) The fact that seals and turtles both have forelimbs that are adapted as

Answer 6

b) The same bone structure is present in Tiktaalik, the nearest sister
taxon to tetrapods, indicating that it was shared by the common
ancestor of tetrapods.

Question 7

At the time Origin of Species was published, what was the main objection to Darwin’s theory among the scientific community?
a) Blending inheritance would tend to dilute out any beneficial traits
over time.
b) Change in species over time was not widely accepted by scientists.
c) They could not agree whether they were descended from monkeys on their grandmother’s or grandfather’s side.
d) Most scientists thought the earth was only about six thousand years old and there had not been time for natural selection to work.
e) The scientific community did not accept the idea of inheritance of

Answer 7

a) Blending inheritance would tend to dilute out any beneficial traits
over time.

Question 8

Darwin’s biological views were influenced by:

a) the writings of Gregor Mendel.
b) the concept of uniformitarianism promoted by Lyell.
c) the estimate of the age of the earth by Archbishop Ussher
d) the theory of plate tectonics.
e) earlier work by Thomas Henry Huxley.

Answer 8

b) the concept of uniformitarianism promoted by Lyell

Question 9

Cystic fibrosis is a recessive condition that affects about 1 in 2,500 babies in the Caucasian population of the United States. Assuming this population is in HWE, please calculate the frequency of the dominant and recessive alleles and the genotype frequencies for both homozygotes and heterozygotes.

What percentage of the US population are carriers for cystic fibrosis (but do not have the disease)?

a) 98%
b) 0.04%
c) 2%
d) 96%
e) 4%

Answer 9

e) 4%

Question 10

Genetic drift changes allele frequencies in finite populations due to

a) differential reproductive success
b) assortative mating
c) mutation
d) migration
e) dumb luck

Answer 10

e) dumb luck

Question 11

A population with 200 individuals has two alleles for a gene: A1
and A2 with allele frequencies of p1 = 0.73 and p2 = 0.27. Neither has a selective advantage and the mutation rate is 0.0001. What is the probability that A2 will become fixed in the population?
a) 0.00027
b) 0.00073
c) 0.073
d) 0.27
e) 0.73

Answer 11

d) 0.27

Question 12

If genetic drift is the only evolutionary mechanism operating in a
population, it will always lead eventually to:
a) loss of genetic diversity, but only in small populations.
b) highly predictable change in allele frequencies.
c) higher fitness of individuals in the population.
d) the random loss of all but one allele.
e) extinction of a species.

Answer 12

d) the random loss of all but one allele.

Question 13

When we say that the genetic code is redundant, we are referring to the fact that ___________.

a) some genes affect more than one trait
b) some codons code for more than one amino acid.
c) humans have more DNA than is ever transcribed and translated
d) some amino acids are coded for by more than one codon
e) some genes have multiple alleles

Answer 13

d) some amino acids are coded for by more than one codon

Question 14

Evidence that the human hemoglobin gene family evolved via gene duplication includes:

a) correspondence in the length and positions of exons and introns among globin genes.
b) high sequence similarity among globin genes.
c) similarity in function among the globin genes.
d) the presence of pseudogenes – nonfunctional loci that are structurally similar to the functional loci.
e) All of the above are evidence that the globin gene family evolved by gene duplication.

Answer 14

e) All of the above are evidence that the globin gene family evolved by gene duplication

Question 15

The most important source of new genes is probably ___________ the underlying mechanism for this is ___________.

a) point mutations/errors during DNA replication
b) polyploidy/duplication of the genome
c) gene duplication/unequal crossing over
d) genetic linkage/chromosome inversions

Answer 15

c) gene duplication/unequal crossing over

Question 16

what is the definition of….

transition

A. A change of a purine to a purine, or a pyrimidine to a pyrimidine
B. A mutation that destroys the function of the resulting gene product
C. A change of a purine to a pyrimidine, or vice versa
D. Reversal of the orientation of a large stretch of DNA
E. A mutation in a single base pair
F. Addition or loss of a small number of base pairs

Answer 16

C. a change of a purine to a pyrimidine, or vice versa

Question 17

what is the definition of….

transition

A. A change of a purine to a purine, or a pyrimidine to a pyrimidine
B. A mutation that destroys the function of the resulting gene product
C. A change of a purine to a pyrimidine, or vice versa
D. Reversal of the orientation of a large stretch of DNA
E. A mutation in a single base pair
F. Addition or loss of a small number of base pairs

Answer 17

A. A change of a purine to a purine, or a pyrimidine to a pyrimidine

Question 18

what is the definition of….

Indel

A. A change of a purine to a purine, or a pyrimidine to a pyrimidine
B. A mutation that destroys the function of the resulting gene product
C. A change of a purine to a pyrimidine, or vice versa
D. Reversal of the orientation of a large stretch of DNA
E. A mutation in a single base pair
F. Addition or loss of a small number of base pairs

Answer 18

F. Addition or loss of a small number of base pairs

Question 19

what is the definition of….

point mutation

A. A change of a purine to a purine, or a pyrimidine to a pyrimidine
B. A mutation that destroys the function of the resulting gene product
C. A change of a purine to a pyrimidine, or vice versa
D. Reversal of the orientation of a large stretch of DNA
E. A mutation in a single base pair
F. Addition or loss of a small number of base pairs

Answer 19

E. a mutation in a single base pair

Question 20

what is the definition of….

loss-of-function mutation or knock-out mutation

A. A change of a purine to a purine, or a pyrimidine to a pyrimidine
B. A mutation that destroys the function of the resulting gene product
C. A change of a purine to a pyrimidine, or vice versa
D. Reversal of the orientation of a large stretch of DNA
E. A mutation in a single base pair
F. Addition or loss of a small number of base pairs

Answer 20

B. A mutation that destroys the function of the resulting gene product

Question 21

what is the definition of….

chromosomal inversion

A. A change of a purine to a purine, or a pyrimidine to a pyrimidine
B. A mutation that destroys the function of the resulting gene product
C. A change of a purine to a pyrimidine, or vice versa
D. Reversal of the orientation of a large stretch of DNA
E. A mutation in a single base pair
F. Addition or loss of a small number of base pairs

Answer 21

D) reversal of the orientation of a large stretch of DNA

Question 22

The most important evolutionary consequence of chromosomal inversions is:

a) polyploidy.
b) they prevent selection from acting on the alleles within the inverted region, thereby increasing genetic diversity.
c) they prevent groups of alleles from being separated by crossing-over, allowing them to be inherited as single “supergenes.”
d) that they reduce the rate of point mutations in the alleles within the inversion.

Answer 22

c) they prevent groups of alleles from being separated by crossing-over, allowing them to be inherited as single “supergenes.”

Question 23

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 typhus than are the dominant homozygotes. Evidence in favor of this hypothesis includes which of the following findings?

A) 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.
B) Salmonella typhi bacteria manipulate their host cells, causing them to express more CFTR protein on their membranes.
C) 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.
D) 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.
E) All of the choices above are correct.

Answer 23

E) All of the choice above are correct

Question 24

If a population is in Hardy-Weinberg equilibium, the Hardy-Weinberg equilibrium principle yields which of the following conclusions?

A) The allele frequencies in a population will not change over time.
B) If the allele frequencies in a population are given by p and q, the genotype frequencies are given by p2and q2.
C) If the allele frequencies in a population are given by p and q, the genotype frequencies are given by p2, 2 pq and q2.
D) The first and second choices are correct.
E) The first and third answers are correct.

Answer 24

E) The first and third answers are correct.