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Chapter 2 Evolutionary Mechanisms
Multiple Choice Questions
1) Most genes are located in the nucleus of the cell, but a few are found in the:
A) chromosomes
B) spindle
C) mitochondria
D) chiasmata
E) vacuoles
Answer: C
2) Variant forms of a particular gene are called:
A) hereditary variants
B) alleles
C) gene morphs
D) subgenes
E) adaptive variation
Answer: B
3) Structural genes are involved in such features as:
A) eye color and susceptibility to certain diseases
B) skin color and metabolism
C) energetic and biosynthetic activities of the body
D) susceptibility to certain diseases and metabolism
E) lifespan and body weight
Answer: A
4) Meiosis results in
A) haploid gametes
B) diploid gametes
C) diploid somatic cells
D) haploid somatic cells
E) none of the above
Answer: C
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5) Codons
A) are three adjacent nucleotide bases
B) code for the production of particular amino acids
C) contribute to protein synthesis
D) all of the above
E) none of the above
Answer: D
6) Not all DNA codes for protein production. Noncoding portions are called
A) intron sequences
B) exon sequences
C) blank DNA
D) messenger DNA
E) reserve DNA
Answer: A
7) Somatic cells
A) contain homologous chromosomes
B) have a haploid number of chromosomes
C) lack sex chromosomes
D) contain fewer mitochondria
E) all of the above
Answer: A
8) Person who carried out research important to the discovery of the composition and structure
of DNA
A) Friedrich Miescher
B) Hugo de Vries
C) Rosalind Franklin
D) Ernst Mayr
E) John Ridley
Answer: C
9) Regulatory genes control such features as
A) eye color and limb length
B) metabolic and biosynthetic activities of the body
C) metabolism and susceptibility to certain diseases
D) skin and hair color
E) none of the above
Answer: B
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10) Point mutations
A) usually involve a doubling of the DNA at a particular locus
B) usually involve increasing or decreasing the chromosome number
C) usually involve spontaneous changes in a gene’s DNA
D) only occur under experimental conditions
E) only occur in junk DNA
Answer: C
11) The term heritability refers to:
A) the degree of similarity between parent and child
B) the proportion of a phenotypic trait’s variance that is attributable to genetic variance
between individuals
C) the proportion of a population’s total phenotypic variation that is attributable to the
effects of the environment
D) the average phenotypic change between succeeding generations
E) those phenotypic traits that are immune to environmental influences
Answer: B
12) The total genetic material in a breeding population is called the
A) population genotype
B) genetic drift
C) dual inheritance
D) gene pool
E) deme
Answer: D
13) Which list best describes gene flow?
A) often accomplished by emigration; aids in the reproductive isolation of populations
B) leads to speciation; refers to breeding within a population
C) often works to prevent or reduce reproductive isolation between populations; promotes
genetic similarity between populations
D) a form of natural selection; generally impossible between species
E) associated with small populations, sometimes referred to as “founder’s effect”
Answer: C
14) The initial stimulus for allopatric speciation is thought to be the
A) geographic isolation of one or more populations from the main portion of the species
B) intensified gene flow between the populations of a species
C) spatial clustering of all members of a species
D) resumption of gene flow after a period of population separation
E) none of these
Answer: A
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15) For modern biologists, the defining feature of a species is usually
A) geographic isolation from other species
B) the phenotypic similarity of its members
C) phenotypic differences from other species
D) reproductive isolation from other species
E) greater than 50% genetic incompatibility
Answer: D
16) Stabilizing natural selection
A) preserves current gene frequencies and phenotypic norms
B) operates during periods of environmental stability
C) contributes to periods of evolutionary stasis in species
D) is not a permanent condition for species
E) all of the above
Answer: E
17) Genetic drift
A) involves the action of strong natural selection
B) works best in large populations with lots of genetic variation
C) involves chance fluctuations in a population’s gene frequencies
D) involves change over long periods of time in large populations
E) acts much like stabilizing selection on a species population
Answer: C
18) Harmful, unexpressed alleles within a species’ gene pool
A) increase the amount of incest that occurs
B) make up the genetic load
C) are eliminated by natural selection
D) quickly lead to geographic isolation for at least one population
E) make extinction more likely
Answer: B
19) H. J. Muller won the Nobel Prize in 1946 for his research
A) on chemical mutations in gold fish
B) X-ray -induced mutations in fruit flies
C) mapping the genes of the fruit flies
D) on human blood groups
E) mapping the double-helix structure of DNA
Answer: B
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20) Sexual selection may involve
A) competition among members of one sex for access to mates
B) differential choice by members of one sex for mates
C) the behaviors of various primate species
D) sexual dimorphism
E) all of the above
Answer: E
21) Phyletic transformation
A) is one of the major forms of speciation in nature
B) results in a strong increase in the number of contemporaneous species
C) is a form of pseudoextinction
D) is one circumstance under which extinction occurs
E) is the result of gene flow
Answer: C
22) Extinction has the effect(s) of
A) reducing both species diversity and the number of available ecological niches
B) eliminating only species with “bad genes”
C) increasing both species diversity and the number of “good genes” shared by all organisms
D) reducing species diversity and opening up ecological niches
E) creating progress in evolutionary patterns
Answer: D
23) Speciation among populations with the same or overlapping geographic ranges is called
A) sympatric speciation
B) parapatric speciation
C) allopatric speciation
D) chronospeciation
E) none of these
Answer: A
24) A group of organic compounds that act as the building blocks for proteins is called
A) nucleotides
B) amino acids
C) codons
D) exons
E) RNA
Answer: B
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25) A trait in its heterozygote condition affords protection against a disease such as a malaria is
called a
A) balanced polymorphism
B) genetic load
C) point mutation
D) hybridization
E) immunity
Answer: A
True/False Questions
26) Showing change in the composition of a population’s gene pool demonstrates that evolution
has occurred.
Answer: TRUE
27) According to the modern synthesis, populations evolve not individuals.
Answer: TRUE
28) Meiosis reduces the chromosome count in somatic cells to the haploid number.
Answer: FALSE
29) All of the genes within a cell are located on chromosomes in the nucleus.
Answer: FALSE
30) The genetic code consists of nucleotide triplets called a codon that codes for the production of
amino acids.
Answer: TRUE
31) There are genes for which the environment has no effect on the expression of the gene.
Answer: TRUE
32) Allopatric speciation usually starts with the intensification of gene flow between and isolated
population and the parent species.
Answer: FALSE
33) Directional natural selection occurs in response to environmental change and results in
modifications of the population’s collective phenotype.
Answer: TRUE
34) Evolution can proceed even if there is no genetic variability.
Answer: FALSE
35) A deme is another term for a species.
Answer: FALSE
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36) When used in genetics the term population refers to organisms that share at least some genes
Answer: FALSE
37) The gene and environment relationship is expressed as: genotype + environment = phenotype
Answer: TRUE
38) Mitochondria contain no genetic material
Answer: FALSE
39) About half of the DNA sequence codes for proteins while the other half codes for other
compounds
Answer: FALSE
40) Genetic flow is the most powerful genetic force for speciation
Answer: FALSE
Short Answer Questions
41) When like mate with mate it is called ________.
Answer: assortative mating
42) The ________ is a balanced polymorphism which gives some protection against malaria in
heterozygous individuals.
Answer: sickle-cell trait
43) ________ can be used to test if there are evolutionary changes taking place in a population.
Answer: Hardy-Weinberg theorem
44) Competition among members of one sex for access to members of the opposite sex is called
________.
Answer: sexual selection
45) ________ is the alteration of a whole species into a new species.
Answer: Phyletic transformation
46) ________ is speciation that begins with geographic isolation of at least one population from the
larger parent species.
Answer: Allopatric speciation
47) ________ are “species” that are made when an evolutionary continuum is arbitrarily divided to
time-defined units.
Answer: Chronospecies
48) A(n) ________ has a haploid number of chromosomes.
Answer: gamete
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49) ________ is often described as the father of genetics.
Answer: Gregor Mendel
50) A(n) ________ is a genetically identical organism reproduced from a single ancestral organism.
Answer: clone
Essay Questions
51) Compare and contrast genotype and phenotype. What is the relationship between the
genotype and phenotype?
52) Describe the process of gamete formation including the stages of meiosis.
53) How does sexual selection differ from natural selection?
54) Describe the process of allopatric speciation. Explain the contributions of natural selection,
isolation, gene flow, genetic drift, and adaptation to the production of new species.
55) In a population of 1000 people, 640 lack hair on the pinna of the ear and 360 people have hair
growing on the pinna which is the recessive trait. Assuming Hardy-Weinberg equilibrium,
what are the allele frequencies for the dominant and recessive traits?
