Question 1

A disadvantage of sexual recombination is that it

Accepted Answer

A)  breaks down combinations of beneficial alleles. 
B)  leads to Muller's ratchet. 
C)  hampers DNA repair. 
D)  permits the elimination of deleterious mutations. 
E)  decreases genetic variation. 
A)  breaks down combinations of beneficial alleles. 
B)  leads to Muller's ratchet. 
C)  hampers DNA repair. 
D)  permits the elimination of deleterious mutations. 
E)  decreases genetic variation.

Question 2

A field experiment is conducted to test for a heterozygote advantage in the survival of a mustard plant.When heterozygotes for the A locus are first crossed,the yield is 200 AA,400 Aa,and 200 aa ( i.e. ,a ratio of 1:2:1).In trial 1,35 AA,44 Aa,and 23 aa plants survive.In trial 2,25 AA,68 Aa,and 21 aa plants survive.In trial 3,27 AA,48 Aa,and 23 aa plants.Based on these results,which statement is true?

Accepted Answer

A)  Only trial 1 shows heterozygote advantage. 
B)  Only trial 2 shows heterozygote advantage. 
C)  Both trials 1 and 2 show heterozygote advantage. 
D)  Only trial 3 shows heterozygote advantage. 
E)  No trial shows heterozygote advantage. 
A)  Only trial 1 shows heterozygote advantage. 
B)  Only trial 2 shows heterozygote advantage. 
C)  Both trials 1 and 2 show heterozygote advantage. 
D)  Only trial 3 shows heterozygote advantage. 
E)  No trial shows heterozygote advantage.

Question 3

Use the following to answer questions :
A cricket has a diploid genome of 1.2 billion base pairs.Assume that there are about 200,000 individuals in the population and that the mutation rate is one per 100 million base pairs.
-About how many new mutations will occur in each generation of the population of crickets?

Accepted Answer

A)  1.2 
B)  12 
C)  200,000 
D)  1 million 
E)  2.4 million 
A)  1.2 
B)  12 
C)  200,000 
D)  1 million 
E)  2.4 million

Question 4

Which statement is true?

Accepted Answer

A)  Two different populations can have the same allele frequencies but different genotype frequencies. 
B)  Populations that are polymorphic have only one allele at a locus. 
C)  If an allele is fixed in a population,that population is polymorphic. 
D)  Allelic frequencies are measures of how a population's genetic variation is distributed among its members. 
E)  A population that is monomorphic has a great deal of genetic variation. 
A)  Two different populations can have the same allele frequencies but different genotype frequencies. 
B)  Populations that are polymorphic have only one allele at a locus. 
C)  If an allele is fixed in a population,that population is polymorphic. 
D)  Allelic frequencies are measures of how a population's genetic variation is distributed among its members. 
E)  A population that is monomorphic has a great deal of genetic variation.

Question 5

The percentage of the genome that encodes functional genes _______ as genome size increases.

Accepted Answer

A)  steadily increases 
B)  increases to a point,and then levels off 
C)  stays more or less the same 
D)  increases at first,and then declines 
E)  steadily decreases 
A)  steadily increases 
B)  increases to a point,and then levels off 
C)  stays more or less the same 
D)  increases at first,and then declines 
E)  steadily decreases

Question 6

A biologist is examining species of plants found in Thailand in the hope of finding a naturally occurring treatment for cancer.This scientist is engaged in

Accepted Answer

A)  an application of Muller's ratchet. 
B)  bioprospecting. 
C)  bioremediation. 
D)  bioinfomatics. 
E)  an application of the principles of convergent evolution. 
A)  an application of Muller's ratchet. 
B)  bioprospecting. 
C)  bioremediation. 
D)  bioinfomatics. 
E)  an application of the principles of convergent evolution.

Question 7

Which observation would provide the strongest evidence that most noncoding DNA is slightly deleterious?

Accepted Answer

A)  Species with larger population sizes have more noncoding DNA. 
B)  Species with smaller population sizes have more noncoding DNA. 
C)  Species with larger genomes lose DNA more slowly through mutational processes than those with smaller genomes. 
D)  Species with larger genomes lose DNA more quickly through mutational processes than those with smaller genomes. 
E)  There is an inverse relationship between the total amount of DNA in the genome and the percentage of the DNA that is noncoding. 
A)  Species with larger population sizes have more noncoding DNA. 
B)  Species with smaller population sizes have more noncoding DNA. 
C)  Species with larger genomes lose DNA more slowly through mutational processes than those with smaller genomes. 
D)  Species with larger genomes lose DNA more quickly through mutational processes than those with smaller genomes. 
E)  There is an inverse relationship between the total amount of DNA in the genome and the percentage of the DNA that is noncoding.

Question 8

If the frequency of an allele is 0.75,how many copies of this allele should be in a population of 300 diploid individuals?

Accepted Answer

A)  75 
B)  150 
C)  225 
D)  300 
E)  450 
A)  75 
B)  150 
C)  225 
D)  300 
E)  450

Question 9

You discover a population of mustard plants and find it to be at Hardy-Weinberg equilibrium with respect to the R locus.Suppose that there are two alleles at this locus and the frequency of one of those alleles (the r-6 allele)is 0.2.Of the individuals that carry at least one r-6 allele,what fraction are heterozygotes?

Accepted Answer

A)  1/9 
B)  1/5 
C)  1/3 
D)  4/5 
E)  8/9 
A)  1/9 
B)  1/5 
C)  1/3 
D)  4/5 
E)  8/9

Question 10

Synonymous substitutions are possible because

Accepted Answer

A)  most changes in DNA are either deleterious or selectively neutral. 
B)  mutation rates are high. 
C)  mutation rates are low. 
D)  most amino acids are specified by more than one codon. 
E)  most codons are specified by more than one amino acid. 
A)  most changes in DNA are either deleterious or selectively neutral. 
B)  mutation rates are high. 
C)  mutation rates are low. 
D)  most amino acids are specified by more than one codon. 
E)  most codons are specified by more than one amino acid.

Question 11

Due to various causes,including DDT poisoning,the population size of whooping cranes was reduced to about two dozen during the 1940s.The population size has since rebounded,and there are now hundreds of whooping cranes.Which would you not expect to see in the current populations of whooping cranes?

Accepted Answer

A)  Very low levels of genetic variation 
B)  Very few heterozygous individuals 
C)  Allele frequencies different from those of historical populations 
D)  Considerable genetic polymorphism 
E)  Genotypic frequencies different from those of historical populations 
A)  Very low levels of genetic variation 
B)  Very few heterozygous individuals 
C)  Allele frequencies different from those of historical populations 
D)  Considerable genetic polymorphism 
E)  Genotypic frequencies different from those of historical populations

Question 12

Which mode of selection operates when individuals at both extremes of the distribution have the highest fitness?

Accepted Answer

A)  Stabilizing selection 
B)  Directional selection 
C)  Positive selection 
D)  Disruptive selection 
E)  Purifying selection 
A)  Stabilizing selection 
B)  Directional selection 
C)  Positive selection 
D)  Disruptive selection 
E)  Purifying selection

Question 13

A nonsynonymous mutation is also called a _______ mutation.

Accepted Answer

A)  silent 
B)  missense 
C)  disruptive 
D)  neutral 
E)  beneficial 
A)  silent 
B)  missense 
C)  disruptive 
D)  neutral 
E)  beneficial

Question 14

What was Darwin's explanation for the evolution of bright colors and other apparently useless (and potentially deleterious)but conspicuous characters in males of many species?

Accepted Answer

A)  Stabilizing selection 
B)  Genetic drift 
C)  Sexual selection 
D)  Disruptive selection 
E)  Gene flow 
A)  Stabilizing selection 
B)  Genetic drift 
C)  Sexual selection 
D)  Disruptive selection 
E)  Gene flow

Question 15

In most mammals,the main role of lysozymes is to

Accepted Answer

A)  perform foregut fermentation. 
B)  carry oxygen in the blood. 
C)  defend the body from bacteria. 
D)  assist in thermoregulation. 
E)  maintain a stable pH. 
A)  perform foregut fermentation. 
B)  carry oxygen in the blood. 
C)  defend the body from bacteria. 
D)  assist in thermoregulation. 
E)  maintain a stable pH.

Question 16

Which is not an example of adaptation?

Accepted Answer

A)  A plant population that is very resistant to drought due to the action of natural selection 
B)  The process by which a plant population became drought resistant 
C)  The increased ability (above baseline)of an individual plant to withstand further drought after it has received a heat shock,which causes the expression of specific proteins that enable more efficient use of water 
D)  A zebra that runs quickly to evade lions 
E)  A lion that runs quickly in order to catch zebra prey 
A)  A plant population that is very resistant to drought due to the action of natural selection 
B)  The process by which a plant population became drought resistant 
C)  The increased ability (above baseline)of an individual plant to withstand further drought after it has received a heat shock,which causes the expression of specific proteins that enable more efficient use of water 
D)  A zebra that runs quickly to evade lions 
E)  A lion that runs quickly in order to catch zebra prey

Question 17

The differential contribution of individuals to the next generation as a function of their different genotypes is known as _______.

Accepted Answer

The answer of The differential contribution of individuals to the...

Question 18

Muller's ratchet is the

Accepted Answer

A)  breaking down of adaptive combinations of genes by recombination. 
B)  elimination of deleterious mutations due to sexual reproduction. 
C)  accumulation of deleterious mutations in asexual lineages. 
D)  crossing over and independent assortment of chromosomes during meiosis. 
E)  maintenance of genetic variation via disruptive selection. 
A)  breaking down of adaptive combinations of genes by recombination. 
B)  elimination of deleterious mutations due to sexual reproduction. 
C)  accumulation of deleterious mutations in asexual lineages. 
D)  crossing over and independent assortment of chromosomes during meiosis. 
E)  maintenance of genetic variation via disruptive selection.

Question 19

The hypothesis of neutral evolution asserts that

Accepted Answer

A)  the rate of molecular mutation is influenced by natural selection. 
B)  most variability in the structure of molecules does not affect their functioning. 
C)  closely related species have more similar molecular structures than do distantly related species. 
D)  organisms evolved through neutral changes in their molecules. 
E)  mutations neither add nor subtract amino acids from molecules. 
A)  the rate of molecular mutation is influenced by natural selection. 
B)  most variability in the structure of molecules does not affect their functioning. 
C)  closely related species have more similar molecular structures than do distantly related species. 
D)  organisms evolved through neutral changes in their molecules. 
E)  mutations neither add nor subtract amino acids from molecules.

Question 20

Which statement is plausible explanation for the typically slow rates of evolution over the long term?

Accepted Answer

A)  Most populations have little genetic variation. 
B)  Natural selection is typically a stabilizing phenomenon. 
C)  Directional selection is commonplace. 
D)  Genetic drift counters the effects of selection,particularly in large populations. 
E)  Mutation rates are very high. 
A)  Most populations have little genetic variation. 
B)  Natural selection is typically a stabilizing phenomenon. 
C)  Directional selection is commonplace. 
D)  Genetic drift counters the effects of selection,particularly in large populations. 
E)  Mutation rates are very high.

Exam 15: Processes of Evolution

A disadvantage of sexual recombination is that it

Which statement is true?

The percentage of the genome that encodes functional genes _______ as genome size increases.

A biologist is examining species of plants found in Thailand in the hope of finding a naturally occurring treatment for cancer.This scientist is engaged in

Which observation would provide the strongest evidence that most noncoding DNA is slightly deleterious?

If the frequency of an allele is 0.75,how many copies of this allele should be in a population of 300 diploid individuals?

Synonymous substitutions are possible because

Due to various causes,including DDT poisoning,the population size of whooping cranes was reduced to about two dozen during the 1940s.The population size has since rebounded,and there are now hundreds of whooping cranes.Which would you not expect to see in the current populations of whooping cranes?

Which mode of selection operates when individuals at both extremes of the distribution have the highest fitness?

A nonsynonymous mutation is also called a _______ mutation.

What was Darwin's explanation for the evolution of bright colors and other apparently useless (and potentially deleterious)but conspicuous characters in males of many species?

In most mammals,the main role of lysozymes is to

Which is not an example of adaptation?

The differential contribution of individuals to the next generation as a function of their different genotypes is known as _______.

Muller's ratchet is the

The hypothesis of neutral evolution asserts that

Which statement is plausible explanation for the typically slow rates of evolution over the long term?

Introduction

The Chemistry and Energy of Life

Nucleic Acids, Proteins, and Enzymes

Cells: the Working Units of Life

Cell Membranes and Signaling

Pathways That Harvest and Store Chemical Energy

The Cell Cycle and Cell Division

Inheritance, Genes, and Chromosomes

DNA and Its Role in Heredity

From Dna to Protein: Gene Expression

Regulation of Gene Expression

Genomes

Biotechnology

Genes, Development, and Evolution

Reconstructing and Using Phylogenies

Speciation

The History of Life on Earth

Bacteria, Archaea, and Viruses

The Origin and Diversification of Eukaryotes

The Evolution of Plants

The Evolution and Diversity of Fungi

Animal Origins and Diversity

The Plant Body

Plant Nutrition and Transport

Plant Growth and Development

Reproduction of Flowering Plants

Plants in the Environment

Fundamentals of Animal Function

Nutrition and Digestion

Breathing

Circulation

Muscle and Movement

Neurons, Sense Organs, and Nervous Systems

Nervous and Endocrine Control

Water and Salts: Excretion

Animal Reproduction

Animal Development

Immunology: Animal Defense Systems

Animal Behavior

The Distribution of Earths Ecological Systems

Populations

Ecological and Evolutionary Consequences of Interactions Within and Among Species

Ecological Communities

The Global Ecosystem

Filters