Mechanisms of Evolution (Revised) - Quizs

Definition: fitness

• ability to survive and reproduce in a specific environment

• organisms with traits well suited to their environment survive and reproduce at a greater rate

• a growing population causes a scarcity of resources

• differences in the DNA sequence

Answer explanation

The correct choice defines fitness as the ability to survive and reproduce in a specific environment, which captures the essence of how well an organism can thrive in its surroundings.

Mutations are important because they bring about

• death of the organism in which they develop

• genetic variation needed for a population to evolve

• benefits for the individual, not for the population

• Hardey-Weinberg equilibrium within a population

Answer explanation

Mutations introduce genetic variation, which is essential for evolution. This variation allows populations to adapt to changing environments, making the correct answer 'genetic variation needed for a population to evolve'.

This is the pattern of natural selection where BOTH of the extreme versions of a trait are more advantageous than the average, so a population evolves in both directions away from the average

• Directional Selection

• Disruptive Selection

• Stabilizing Selection

• Radical Selection

Answer explanation

Disruptive Selection occurs when both extreme traits are favored over the average, leading to a population evolving in both directions from the mean. This contrasts with Directional and Stabilizing Selection, which favor average traits.

A drastic reduction in the size of a population that can change allele frequencies is called

• the bottleneck effect

• the founder effect

• the gene flow effect

• the Thanos effect

Answer explanation

The bottleneck effect occurs when a significant reduction in population size leads to a loss of genetic diversity and changes in allele frequencies. This is the correct answer as it directly describes the drastic reduction in population size.

What is biological fitness defined as?

• The ability to perform physical exercises for a long duration

• The ability to survive and pass on one's genes in a given environment

• The ability to compete in nature without human help

• The ability to adapt to any environment quickly

Answer explanation

Biological fitness refers to an organism's ability to survive and reproduce in its environment, ensuring the continuation of its genes. This definition highlights the importance of both survival and reproduction.

Which of the following is an example of directional selection?

• Birds with average-sized beaks are more successful than those with very large or very small beaks.

• In a population of moths, darker moths are more likely to survive in a polluted environment.

• Fish with both very large and very small fins are more likely to survive than those with average-sized fins.

• In a population of plants, those with medium height are more likely to survive than those with very tall or very short stems.

Answer explanation

Directional selection favors one extreme phenotype over others. In this case, darker moths survive better in polluted environments, illustrating how a specific trait (dark coloration) enhances survival.

Insects become resistant to pesticides very quickly, sometime in one generation. If an insect is resistant to the chemical, most of the offspring will also be resistant. Considering that insect generations can be a matter of weeks, insects in an area can become immune to a chemical within months.

• Mutation

• Natural Selection

• Genetic Drift

• Gene Flow

Answer explanation

Natural selection explains how insects quickly develop resistance to pesticides. Those with resistance survive and reproduce, passing on the trait to their offspring, leading to rapid population-wide immunity.

Which type of selection favors one extreme phenotype?

• Balancing selection

• Disruptive selection

• Directional selection

• Stabilizing selection

Answer explanation

Directional selection favors one extreme phenotype by increasing its frequency in the population, while other phenotypes are selected against. This leads to a shift in the population's traits towards that extreme.

Which of the following is NOT a mechanism of evolution?

• Random mating

• Natural selection

• Gene Flow

• Mutation

• Genetic Drift

Answer explanation

Random mating is not a mechanism of evolution; it refers to the way individuals pair up without regard to genetic traits. In contrast, natural selection, gene flow, mutation, and genetic drift actively influence evolutionary change.

What happens to new traits that HELP organisms survive over time?

• Nothing

• That trait becomes MORE COMMON in the population

• That trait becomes LESS COMMON in a population

• Equally common

Answer explanation

New traits that help organisms survive are favored by natural selection. Over time, these beneficial traits become more common in the population as individuals with these traits are more likely to survive and reproduce.