Chapter 15 and 16 Study Guide Answers



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

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