Chapter 15 and 16 Study Guide Answers
Section 15-1
VOCABULARY REVIEW
1. Evolution is the development of new types of
organisms from preexisting types of organisms
over time.
2. Natural selection is a process in which organisms
best suited to their environment reproduce more
successfully than other organisms.
MULTIPLE CHOICE
1. d 2. c 3. a 4. d 5. c
SHORT ANSWER
1. Since acquired traits are not genetically determined,
they cannot be passed on to offspring.
Therefore, they cannot cause a population to
change over generations.
2. Darwin extended Malthus’ ideas to populations of
all organisms and reasoned that the environment
limits the populations of all organisms by causing
deaths or limiting births.
3. Evolution is the change of populations of organisms
over time; natural selection is the mechanism
by which evolution occurs.
4. Lamarck would have said that the ancestors of
modern-day giraffes had short necks but stretched
their necks as they tried to reach leaves in trees; so,
their descendants were born with longer necks.
Darwin would have said that in a population of
ancestral giraffes, some had slightly longer necks
than others; the long-necked giraffes were better
able to feed on tree leaves and as a result produced
more offspring. Over time, the proportion of longnecked
giraffes in the population increased.
STRUCTURES AND FUNCTIONS
The bird in B appears to have greater fitness, since it
has produced more offspring.
Section 15-2
VOCABULARY REVIEW
1. A homologous structure is an anatomical structure
that occurs in different species and originated by
heredity from a structure in a common ancestor;
analogous structures have closely related functions
but are not derived from the same ancestral
structure.
2. A fossil is the evidence or remains of a preexisting
organism; the principle of superposition states
that if a sequence of sedimentary rock strata have
been undisturbed, the oldest strata will be at the
bottom of the sequence and younger strata will be
on top. The relative age of the strata is usually
determined by comparing the fossils contained in
the strata.
3. The relative age of a fossil or rock is simply an
indication of whether the fossil or rock is younger
or older than another fossil or rock; the absolute
age of a rock is the rock’s age in years.
MULTIPLE CHOICE
1. b 2. c 3. b 4. a 5. a
SHORT ANSWER
1. A biologist would concentrate on homologous features,
since they originated in a shared ancestor.
2. The animal evolved from an ancestor in which
that structure was functional.
3. In biogeography studies, similar animals that seem
to be closely related are adapted to different environments
in nearby areas. Also, in areas that are
widely separated animals that seem to be unrelated
are observed to have similar adaptations to
similar environments in the separate areas.
4. Fossils show that a group of organisms, such as
marine mammals, have changed over time to
adapt to different environments.
5. The environment will not select for or against
organisms that have a particular structure unless
that structure affects the organisms’ fitness.
STRUCTURES AND FUNCTIONS
a, youngest fossil; b, mammal fossils; c, first dinosaurs;
d, first land plants; e, trilobites; f, oldest fossil
Section 15-3
VOCABULARY REVIEW
1. the evolution of Caribbean anole lizards
2. Examples may include different breeds of dogs,
cats, cattle, or food crops.
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Modern Biology Study Guide Answer Key
3. some flowers and insects; animals and microbes
4. the evolution of Caribbean anole lizards with similar
adaptations on separate islands
5. Two examples are the evolution of the Galápagos
finches and the evolution of domestic dogs.
6. evolution of resistance to pesticides by insect populations,
of plants to herbicides, and evolution of
resistance to antibiotics by disease-causing
bacteria
MULTIPLE CHOICE
1. b 2. c 3. a 4. d 5. a
SHORT ANSWER
1. Adaptive radiation occurs when a new population
in a new environment, such as an island, undergoes
divergent evolution until the descendant populations
fill many parts of the environment.
2. Answer will vary, but could include the lizards
moving to an area where the trees are still healthy,
or they could adapt to live in another part of the
environment, such as living in small shrubs or on
the ground. The lizards could also go extinct if
they could not move to another area or adapt to
the new environment.
3. Answers will vary, but could include domestic
dogs, domestic cats, cattle, sheep, and pigs for
animals and corn, wheat, fruit trees, such as
apples or oranges, and flowers, such as roses or
orchids.
4. The long-lived species would be more likely to
become extinct after a sudden environmental
change. The short-lived species, with large numbers
of offspring, would be more likely to adapt to the
changing environment. The short-lived species can
adapt more easily because of the larger pool of
genetic variations available in the larger population.
STRUCTURES AND FUNCTIONS
divergent evolution; approximately 16 million years
ago; the galago
Section 16-1
VOCABULARY REVIEW
1. Population genetics is the study of evolution from
a genetic point of view.
2. A gene pool is the total genetic information available
in a population.
3. Allele frequency is the frequency of a certain allele
among all alleles of the same gene in a population.
4. Phenotype frequency is the frequency of individuals
with a particular phenotype in a population.
5. Hardy-Weinberg genetic equilibrium is a condition
in which the allele frequencies in a population
remain the same from generation to generation.
MULTIPLE CHOICE
1. b 2. c 3. b 4. d 5. a
SHORT ANSWER
1. Individuals represented by the two ends are those
with extreme variations of a specific trait.
2. Variations arise through mutation, recombination
during meiosis, and the random pairing of gametes
during fertilization.
3. (1) No net mutations occur; (2) individuals neither
enter nor leave the population; (3) the population
is large; (4) individuals mate randomly; and (5)
selection does not occur.
4. no, because those genes are not available for the
next generation
STRUCTURES AND FUNCTIONS
Phenotype frequencies: red = 0.625 0.625 = 0.391;
white = 0.375 0.375 = 0.141; pink = 1 – 0.391 – 0.141 =
0.468. Allele frequencies: R = 0.391 (0.468 2) =
0.625; r = 0.141 (0.468 2) = 0.375.
Section 16-2
VOCABULARY REVIEW
1. Immigration is the movement of individuals into a
population. Emigration is the movement of individuals
out of a population.
2. Gene flow is the movement of genes from one population
to another. Genetic drift is a change in allele
frequencies in a population due to random events.
3. Random mating is mating that occurs without
regard to genetic makeup. Assortative mating is
mating based on similarity of characteristics.
4. In stabilizing selection, individuals with the average
form of a trait have the highest fitness. In
directional selection, individuals with one extreme
form of a trait have the highest fitness.
MULTIPLE CHOICE
1. c 2. d 3. a 4. c 5. b
SHORT ANSWER
1. mutations, gene flow, genetic drift, nonrandom
mating, and natural selection
2. By producing totally new alleles for a trait, mutations
can change allele frequencies.
3. Matings with some degree of kinship may occur,
increasing the chance of offspring with disorders
caused by recessive genes.
4. The bright coloration may increase a male’s
chances of being selected for mating by a female.
5. Genetic homozygosity leaves no variation for natural
selection to act on. Therefore, a new disease
could wipe out the entire population.
6. directional selection; the cow would not eliminate all
white flowers because the allele for white flowers is
also carried by plants with pink flowers, which are
not eaten. Crosses between plants with pink flowers
would continue to produce some plants with white
flowers.
STRUCTURES AND FUNCTIONS
a, disruptive; b, directional; c, stabilizing
Section 16-3
VOCABULARY REVIEW
1. Morphology is the internal and external structure
and appearance of an organism.
2. Geographic isolation is the physical separation of
members of a population.
3. Punctuated equilibrium is a pattern of species
formation in which periods of sudden speciation
are preceded and followed by long periods with
little speciation.
MULTIPLE CHOICE
1. d 2. a 3. b