Deck 5: Variation Among Individuals

Question 1

Genes that are derived from a common ancestral sequence,and are separated by a speciation event such as the RNASE1 gene in douc langur monkeys and the RNASE1 gene in humans,are described as ________.

A) duplicated genes
B) orthologous genes
C) homologous genes
D) paralogous genes
E) derived genes

Answer 1

B

Question 2

Which of the following is NOT one of the types of variation that occurs within individuals?

A) genetic variation
B) environmental variation
C) normalizing variation
D) genotype-by-environment variation

Answer 2

C

Question 3

What DNA modifications characterize epigenetic marks?

Answer 3

Attachment of methyl groups to cytosine nucleotides in DNA,or other similar chemical modifications to DNA.

Question 4

An organism that develops different phenotypes in different environments is said to exhibit what trait?

Question 5

What does one call a mutation that occurs in a DNA sequence that changes the amino acid specified by that sequence?

Question 6

In DNA,the substitution of a purine for a purine or a pyrimidine for a pyrimidine is called a(n)________.

A) inversion
B) transmutation
C) transversion
D) transition
E) in-kind substitution

Question 7

The genetic code,which specifies the three-letter codons that specify particular amino acids,is said to be redundant because ________.

A) amino acid sequences are produced by different alleles
B) it is observed in virtually all know organisms
C) one codon can code for more than one amino acid
D) phenotypic variation is observed depending on the codon usage
E) some amino acids are coded for by more than one codon

Question 8

A hypothetical population has two alleles for a gene: A and a.In a random sample of 50 individuals,20 are homozygous for a,20 are homozygous for A,and 10 are heterozygous.What is the frequency of A?

A) 20%
B) 40%
C) 50%
D) 60%
E) 80%

Question 9

In DNA,the substitution of a purine for a pyrimidine or a pyrimidine for a purine is called a(n)________.

A) inversion
B) transmutation
C) transversion
D) transition
E) substitution

Question 10

The haploid human genome contains approximately 3.2 billion base pairs.How many mutations,on average,does each individual inherit from each of the gametes that united to form the zygotes from which he or she grew?

A) 3
B) 36
C) 360
D) 3,600

Question 11

Organisms with more than two chromosome sets are said to be ________.

A) multiploid
B) polyploid
C) diploid
D) haploid
E) None of the above.

Question 12

Daphnia pulex grows protective armor upon sensing chemicals produced by the predatory phantom midge by the process of ________.

A) barrier defense
B) inducible defense
C) stimulatory defense
D) predatory defense

Question 13

Chromosome inversions often result from a multistep process that begins when radiation causes ________.

A) a duplication event, followed by reannealing of chromosomes
B) four double-stranded breaks in a chromosome
C) two double-stranded breaks in a chromosome
D) two single-stranded breaks in a chromosome

Question 14

Frequencies of inversions and/or allele frequencies often vary regularly when examined over a geographic area changing in either latitude or climate.This type of regular change is called a ________.

A) zonality
B) cline
C) gradient
D) biome

Question 15

The patterns of phenotypes an individual may develop upon exposure to different environments is called its ________.

A) predictability norm
B) variability norm
C) response norm
D) reaction norm

Question 16

What does one call a mutation that occurs in a DNA sequence,but leaves the resulting amino acid sequence unchanged?

Question 17

Many studies on genetic variation in humans have been done with the perception of taste.The chemical phenylthiocarbamide (PTC)has been used extensively in these studies.Although many individuals cannot taste PTC,many individuals find the taste of PTC to be ________.

A) umami
B) salty
C) sour
D) bitter
E) sweet

Question 18

The process of producing proteins from DNA involves two different steps.What is the term used to describe each step,and what happens during each of these steps?

Question 19

Genes that are duplicated within a genome and later diverge in function,such as the RNASE1 and RNASE1B genes in douc langur monkeys,are described as ________.

A) duplicated genes
B) orthologous genes
C) homologous genes
D) paralogous genes
E) derived genes

Question 20

According to the studies of Eyre-Walker and Keightley (2007),there appear to be four types of mutations observed in most organisms.Which of the following is NOT a type of mutation that is observed?

A) deleterious
B) lethal
C) neutral
D) additive
E) beneficial

Question 21

Explain the relationship between genotype and phenotype with respect to the ability in humans to taste phenylthiocarbamide (PTC),and the correlation of this ability to the type 2 taste receptors (TAS2Rs).How does the conformation of the TASTRs receptors affect the ability to sense the bitter taste of phenylthiocarbamide?

Question 22

Explain the function of retroposition (retroduplication)in gene duplication.Describe the cellular mechanism used for this method of gene duplication,and the manner in which these typically nonfunctional pseudogenes can become active,functional genes.

Question 23

Unequal crossing over often results in the formation of duplicate copies of existing genes.At what phase of meiosis can unequal crossing over occur,and why does this happen?

Question 24

In the mutation accumulation experiments of Dee Denvers and colleagues (2004)with Caenorhabditis elegans,deleterious mutations were observed to accumulate at a slow but steady rate when the populations were grown in a benign environment,with optimal temperature and humidity,minimal crowding of individuals,abundant food,and no predators or parasites.Control lines grown under normal conditions did not accumulate mutations at the same rate.After 240 generations,experimental lines that had accumulated substantial mutations were removed from the benign environment and these lines were propagated.Explain the results once the recovery lines were established,and how this experiment demonstrates the significance of natural selection in the evolutionary process.

Question 25

In experiments with Caenorhabditis elegans,deleterious mutations accumulate at a slow but steady rate when the populations are grown in as benign an environment as possible,with optimal temperature and humidity,minimal crowding of individuals,abundant food,and no predators or parasites.From what important evolutionary force do these conditions insulate C.elegans?

Question 26

Genes can be duplicated when a processed messenger RNA,from which introns have been spliced out,is reverse-transcribed to form a double-stranded DNA segment that is reintegrated into the main chromosome.What is the name for this process that may form nonfunctional pseudogenes?

Question 27

What is the term given to the average frequency of heterozygotes at all loci of an individual? This value can also be expressed as the fraction of genes that are heterozygous in the genotype of an average individual.

Question 28

Chromosome inversions often have a major impact on evolutionary processes.Describe the process and causes whereby chromosome inversions occur.Describe the effect chromosome inversions have on the process of meiosis,and provide a specific example of chromosome inversions discussed in the text.

Question 29

What is the term used to describe the smallest possible mutation in a DNA strand,which involves only one base?

Question 30

Organisms that exhibit different phenotypes in different environments are said to exhibit phenotypic plasticity.Using the tobacco hornworm,Manduca sexta,studied by Suzuki and Nijhout,describe the experiments done to illustrate the dependence of color on temperature.Be sure to explain the importance of using reaction norms in this type of study.