Question 1

Explain how disruptive selection could lead to the development of two species from one original founding population.

Accepted Answer

Disruptive selection favors the extreme phenotypes of a population. Over time, this could lead to organisms so different that they are no longer able to reproduce with each other.

Question 2

Evolution by genetic drift is most obvious in:

Accepted Answer

A) large populations. 
B) aquatic organisms. 
C) small populations. 
D) invertebrate species. 
E) migratory species. 
A) large populations. 
B) aquatic organisms. 
C) small populations. 
D) invertebrate species. 
E) migratory species. C

Question 3

Explain how a recessive trait can be the most frequent phenotype in a population.

Accepted Answer

Selection pressures can cause genetic drift via directional selection. This could favor the organisms showing the recessive trait while removing the dominant allele from the gene pool.

Question 4

Imagine that a mutation for red eye color becomes very common in a population of flies because female flies in this population prefer to mate with red-eyed males. This is an example of:

Accepted Answer

A) directional selection. 
B) stabilizing selection. 
C) disruptive selection. 
D) sexual selection. 
E) genetic drift. 
A) directional selection. 
B) stabilizing selection. 
C) disruptive selection. 
D) sexual selection. 
E) genetic drift.

Question 5

Imagine that a species of bird with an intermediate beak size becomes two separate species with large and small beaks. This is an example of:

Accepted Answer

A) directional selection. 
B) stabilizing selection. 
C) disruptive selection. 
D) sexual selection. 
E) genetic drift. 
A) directional selection. 
B) stabilizing selection. 
C) disruptive selection. 
D) sexual selection. 
E) genetic drift.

Question 6

A population that maintains several different phenotypes displays ________.

Accepted Answer

balanced p

Question 7

Natural selection causes genetic changes in populations. True or False?

Accepted Answer

A) True 
 B)False

Question 8

Within a large population, if no mutations occur, no migration occurs, all matings are random, and each individual has an equal chance of reproducing, which of the following will probably happen?

Accepted Answer

A) Extinction will result. 
B) A bottleneck will occur. 
C) Natural selection will occur at the normal rate for that species. 
D) A change in allele frequency will lead to rapid evolution. 
E) No evolution will occur. 
A) Extinction will result. 
B) A bottleneck will occur. 
C) Natural selection will occur at the normal rate for that species. 
D) A change in allele frequency will lead to rapid evolution. 
E) No evolution will occur.

Question 9

Mutations:

Accepted Answer

A) can be helpful, neutral, or harmful to individuals. 
B) arise due to environmental pressures. 
C) are caused by natural selection. 
D) limit the potential for evolution. 
A) can be helpful, neutral, or harmful to individuals. 
B) arise due to environmental pressures. 
C) are caused by natural selection. 
D) limit the potential for evolution.

Question 10

Suppose a small population of deer is introduced to an island. All the original males have 6 to 10 points on their antlers, and the average male has 8 points. After several generations, if most males have antlers with 10 points and no males have 6 points, this is an example of ________ selection.

Accepted Answer

The answer of Suppose a small population of deer is...

Question 11

Genetic drift results in a change in gene frequencies because:

Accepted Answer

A) gene flow within the population is less than gene flow between populations. 
B) the population is so large that natural selection has little noticeable effect. 
C) the population size is so small that chance occurrences can alter gene frequencies. 
D) the population has not yet stabilized. 
A) gene flow within the population is less than gene flow between populations. 
B) the population is so large that natural selection has little noticeable effect. 
C) the population size is so small that chance occurrences can alter gene frequencies. 
D) the population has not yet stabilized.

Question 12

Male fish that display a bright blue color attract more mates as well as more predators. Maintaining that blue gene in the population is an example of:

Accepted Answer

A) the founder effect. 
B) a population bottleneck. 
C) coevolution. 
D) genetic drift. 
E) sexual selection. 
A) the founder effect. 
B) a population bottleneck. 
C) coevolution. 
D) genetic drift. 
E) sexual selection.

Question 13

Suppose a population of mostly sand-colored crabs migrates from a sand beach to a pebble beach and evolves a darker, speckled coloration that closely resembles the pebble beach. This is an example of:

Accepted Answer

A) directional selection. 
B) stabilizing selection. 
C) disruptive selection. 
D) sexual selection. 
E) genetic drift. 
A) directional selection. 
B) stabilizing selection. 
C) disruptive selection. 
D) sexual selection. 
E) genetic drift.

Question 14

Suppose that the only population of a certain reptile species lives on an African mountain. If you could prevent all movement of individuals out of this large but isolated population, which of the following describes the most likely future of this reptile population?

Accepted Answer

A) Evolution will promptly cease. 
B) The population will go extinct after a few generations because of inbreeding. 
C) Evolution will continue because of mutations, assortative mating, and genetic drift. 
D) The bottleneck effect will cause major evolutionary changes in the isolated population. 
E) The population will survive only as long as the environment remains constant. 
A) Evolution will promptly cease. 
B) The population will go extinct after a few generations because of inbreeding. 
C) Evolution will continue because of mutations, assortative mating, and genetic drift. 
D) The bottleneck effect will cause major evolutionary changes in the isolated population. 
E) The population will survive only as long as the environment remains constant.

Question 15

The elaborate courtship displays common among animals are the result of:

Accepted Answer

A) random mating. 
B) sexual selection. 
C) spontaneous mutations. 
D) stabilizing selection. 
E) disruptive selection. 
A) random mating. 
B) sexual selection. 
C) spontaneous mutations. 
D) stabilizing selection. 
E) disruptive selection.

Question 16

Antibiotic resistance is an example of ________ in bacteria.

Accepted Answer

The answer of Antibiotic resistance is an example of ________...

Question 17

In Central Africa, the frequency of the sickle-cell allele has remained stable over the years because the allele protects against malaria. In the United States, malaria was eradicated by eliminating the mosquito that spreads the disease. The decreasing frequency of the sickle-cell allele in African Americans since malaria was eliminated in the United States is an example of:

Accepted Answer

A) directional selection. 
B) stabilizing selection. 
C) disruptive selection. 
D) genetic drift. 
E) the founder effect. 
A) directional selection. 
B) stabilizing selection. 
C) disruptive selection. 
D) genetic drift. 
E) the founder effect.

Question 18

According to the Hardy-Weinberg principle, if 75% of the alleles in the gene pool are A1 and 25% are A2, what is the proportion of individuals with genotype A1A2 in this population?

Accepted Answer

A) 0)1875 
B) 0)5625 
C) 0)375 
D) 0)0625 
E) 0)025 
A) 0)1875 
B) 0)5625 
C) 0)375 
D) 0)0625 
E) 0)025

Question 19

Which of the following is an example of assortative mating?

Accepted Answer

A) A dominant male elephant mates with most females in a group, excluding other males from mating with the females. 
B) A female mouse chooses a mate because he is the same color that she is. 
C) A female sparrow chooses a mate because he attracts her by singing the correct song. 
D) A female sheep chooses a mate because he has previously mated with many females. 
E) A female lizard chooses to mate with the first male she encounters. 
A) A dominant male elephant mates with most females in a group, excluding other males from mating with the females. 
B) A female mouse chooses a mate because he is the same color that she is. 
C) A female sparrow chooses a mate because he attracts her by singing the correct song. 
D) A female sheep chooses a mate because he has previously mated with many females. 
E) A female lizard chooses to mate with the first male she encounters.

Question 20

Habitat loss, natural catastrophes, and/or excessive harvesting of a species often result in:

Accepted Answer

A) increased mutation rates. 
B) population bottlenecks. 
C) increased fitness of individuals. 
D) artificial selection. 
E) increased gene flow. 
A) increased mutation rates. 
B) population bottlenecks. 
C) increased fitness of individuals. 
D) artificial selection. 
E) increased gene flow.

Exam 15: How Populations Evolve

Explain how disruptive selection could lead to the development of two species from one original founding population.

Evolution by genetic drift is most obvious in:

Explain how a recessive trait can be the most frequent phenotype in a population.

Imagine that a mutation for red eye color becomes very common in a population of flies because female flies in this population prefer to mate with red-eyed males. This is an example of:

Imagine that a species of bird with an intermediate beak size becomes two separate species with large and small beaks. This is an example of:

A population that maintains several different phenotypes displays ________.

Natural selection causes genetic changes in populations. True or False?

Within a large population, if no mutations occur, no migration occurs, all matings are random, and each individual has an equal chance of reproducing, which of the following will probably happen?

Mutations:

Suppose a small population of deer is introduced to an island. All the original males have 6 to 10 points on their antlers, and the average male has 8 points. After several generations, if most males have antlers with 10 points and no males have 6 points, this is an example of ________ selection.

Genetic drift results in a change in gene frequencies because:

Male fish that display a bright blue color attract more mates as well as more predators. Maintaining that blue gene in the population is an example of:

Suppose a population of mostly sand-colored crabs migrates from a sand beach to a pebble beach and evolves a darker, speckled coloration that closely resembles the pebble beach. This is an example of:

Suppose that the only population of a certain reptile species lives on an African mountain. If you could prevent all movement of individuals out of this large but isolated population, which of the following describes the most likely future of this reptile population?

The elaborate courtship displays common among animals are the result of:

Antibiotic resistance is an example of ________ in bacteria.

According to the Hardy-Weinberg principle, if 75% of the alleles in the gene pool are A1 and 25% are A2, what is the proportion of individuals with genotype A1A2 in this population?

Which of the following is an example of assortative mating?

Habitat loss, natural catastrophes, and/or excessive harvesting of a species often result in:

An Introduction to Life on Earth

Atoms, Molecules, and Life

Biological Molecules

Cell Structure and Function

Cell Membrane Structure and Function

Energy Flow in the Life of a Cell

Capturing Solar Energy: Photosynthesis

Harvesting Energy: Glycolysis and Cellular Respiration

The Continuity of Life: Cellular Reproduction

Patterns of Inheritance

Dna: the Molecule of Heredity

Gene Expression and Regulation

Biotechnology

Principles of Evolution

The Origin of Species

The History of Life

Systematics: Seeking Order Amidst Diversity

The Diversity of Prokaryotes and Viruses

The Diversity of Protists

The Diversity of Plants

The Diversity of Fungi

Animal Diversity I: Invertebrates

Animal Diversity Ii: Vertebrates

Animal Behavior

Population Growth and Regulation

Community Interactions

How Do Ecosystems Work

Earths Diverse Ecosystems

Conserving Earths Biodiversity

Homeostasis and the Organization of the Animal Body

Circulation

Respiration

Nutrition and Digestion

The Urinary System

Defenses Against Disease

Chemical Control of the Animal Body: the Endocrine System

The Nervous System

The Senses

Action and Support: the Muscles and Skeleton

Animal Reproduction

Animal Development

Plant Anatomy and Nutrient Transport

Plant Reproduction and Development

Plant Responses to the Environment

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