AP Bio CH 19 Quiz

2.

Drug-resistance mutations occur in bacteria

Only when they are exposed to the drug to which they become resistant.
More often when they are exposed to the drug.
At any time, even when they are not exposed to the drug.
Only when they are exposed to radiation or other mutagens.

Correct Answer

A. At any time, even when they are not exposed to the drug.

Explanation

Drug-resistance mutations can occur in bacteria at any time, even when they are not exposed to the drug. This is because mutations can happen spontaneously in the bacterial DNA, leading to the development of resistance to certain drugs. These mutations can occur due to various factors such as errors during DNA replication or exposure to environmental stressors. Therefore, bacteria can acquire drug resistance even in the absence of drug exposure, making the given answer the correct explanation.

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3.

Which of the following is true about genetic drift?

It is more likely to occur in a large population than in a small population.
It may lead to an allele's becoming fixed in a population when its alternative allele is lost from the population.
It increases the number of heterozygotes in a population.
It increases the level of rare alleles in a population.

Correct Answer

A. It may lead to an allele's becoming fixed in a population when its alternative allele is lost from the population.

Explanation

Genetic drift refers to the random changes in allele frequencies in a population over time. It is more likely to occur in small populations because chance events can have a greater impact on allele frequencies. When genetic drift occurs, it can lead to the loss of an allele from a population, causing the remaining allele to become fixed. This means that all individuals in the population will have the same allele for that particular gene. Therefore, the statement that genetic drift may lead to an allele's becoming fixed in a population when its alternative allele is lost from the population is true.

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4.

The bottleneck effect is thought to be responsible for the loss of variability and loss of fertility in the cheetah species.

True
False

Correct Answer

A. True

Explanation

The bottleneck effect refers to a phenomenon where a population undergoes a drastic reduction in size, resulting in a limited gene pool and decreased genetic diversity. In the case of cheetahs, it is believed that a bottleneck event occurred in their evolutionary history, leading to a significant decrease in their genetic variability. This reduction in genetic diversity can have negative consequences, including reduced fertility and increased vulnerability to diseases and environmental changes. Therefore, it is true that the bottleneck effect is thought to be responsible for the loss of variability and fertility in the cheetah species.

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5.

Industrial melanism in peppered moths in England is an example of stabilizing selection.

True
Fasle

Correct Answer

A. Fasle

Explanation

The statement is false because industrial melanism in peppered moths in England is actually an example of directional selection, not stabilizing selection. Stabilizing selection occurs when the extremes of a trait are selected against, leading to the average phenotype being favored. In the case of peppered moths, the dark-colored melanic form became advantageous in polluted industrial areas, leading to an increase in its frequency and a decrease in the light-colored form. This is a clear example of directional selection, where one extreme of the trait is favored over the other.

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6.

Gene mutation occurs at any time, without respect to the mutation's adaptive value or benefit to the organism.

True
False

Correct Answer

A. True

Explanation

Gene mutation occurs randomly and can happen at any time, regardless of whether it provides any advantage or benefit to the organism. This means that mutations can occur even if they do not improve the organism's ability to survive or reproduce. Therefore, the statement is true.

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7.

The Hardy-Weinberg equilibrium is usually met in most populations in changing environments.

True
False

Correct Answer

A. False

Explanation

The statement is false because the Hardy-Weinberg equilibrium assumes that certain conditions are met, such as a large population size, random mating, no migration, no natural selection, and no mutation. In reality, most populations are subject to changing environments which can disrupt these conditions and prevent the population from being in Hardy-Weinberg equilibrium. Therefore, the statement that the equilibrium is usually met in most populations in changing environments is incorrect.

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8.

An example of the founder effect is seen in populations such as the Amish in Pennsylvania, in which unusual genes are found in large numbers in the isolated population.

True
False

Correct Answer

A. True

Explanation

The statement is true because the founder effect refers to a situation where a small group of individuals founds a new population, resulting in a limited genetic diversity. In the case of the Amish population in Pennsylvania, their ancestors were a small group of individuals who migrated and settled in the area, leading to a restricted gene pool. As a result, certain unusual genes or genetic disorders can be found in high frequencies within the isolated population. This is a classic example of the founder effect.

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1

AP Bio Ch 19 Quiz

All the members of a single species that occupy a particular area at the same time are known as a

Quiz Preview

Drug-resistance mutations occur in bacteria

Which of the following is true about genetic drift?

The bottleneck effect is thought to be responsible for the loss of variability and loss of fertility in the cheetah species.

Industrial melanism in peppered moths in England is an example of stabilizing selection.

Gene mutation occurs at any time, without respect to the mutation's adaptive value or benefit to the organism.

The Hardy-Weinberg equilibrium is usually met in most populations in changing environments.

An example of the founder effect is seen in populations such as the Amish in Pennsylvania, in which unusual genes are found in large numbers in the isolated population.