AP Biology Practice Quiz: Introduction to Natural Selection

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 15 questions to check your progress.

Question 1 of 15

According to the provided text, what is the role of natural selection in the process of evolution?

A)It is a minor, infrequent event.B)It is the final outcome of evolution.C)It is a major mechanism of evolution.D)It is the sole cause of genetic mutation.

All Questions (15)

According to the provided text, what is the role of natural selection in the process of evolution?

A) It is a minor, infrequent event.

B) It is the final outcome of evolution.

C) It is a major mechanism of evolution.

D) It is the sole cause of genetic mutation.

Correct Answer: C

The content explicitly states that 'Natural selection is a major mechanism of evolution.'

Based on Darwin's theory as described, what is the direct consequence of competition for limited resources within a population?

A) Guaranteed survival for all individuals.

B) Differential survival.

C) An increase in available resources.

D) The immediate creation of new species.

Correct Answer: B

The text states that 'competition for resources leads to differential survival,' where some individuals are more likely to survive than others.

How is the concept of 'evolutionary fitness' measured?

A) By an organism's physical strength and speed.

B) By an organism's lifespan.

C) By an organism's reproductive success.

D) By an organism's complexity.

Correct Answer: C

The provided content specifies that 'Evolutionary fitness is measured by an organism's reproductive success.'

A population of plants experiences a sudden and prolonged increase in rainfall, an abiotic environmental change. How might this affect the population's evolution?

A) Evolution will stop until the environment stabilizes.

B) All plants will be equally affected, leading to no evolutionary change.

C) The rate and direction of evolution may be altered.

D) The population will develop favorable traits instantly.

Correct Answer: C

The text explains that 'Fluctuations in biotic and abiotic environments can affect the rate and direction of evolution,' indicating that such a change can alter the evolutionary path of the population.

Which factor is identified as a primary cause of the differential survival described in Darwin's theory?

A) Random chance alone.

B) Competition for resources.

C) Geographic isolation.

D) The desire of organisms to change.

Correct Answer: B

The content clearly states that 'competition for resources leads to differential survival.'

An individual possessing a 'favorable phenotype' is more likely to survive and reproduce. This directly contributes to which of the following?

A) Lower genetic variation in the next generation.

B) A decrease in the population size.

C) Higher evolutionary fitness.

D) Increased competition for resources.

Correct Answer: C

Since evolutionary fitness is measured by reproductive success, and individuals with favorable phenotypes are more likely to reproduce, these individuals have higher evolutionary fitness.

How does natural selection primarily affect a population over many generations?

A) It causes all individuals to become identical.

B) It leads to an increase in the frequency of individuals with favorable phenotypes.

C) It prevents any changes to the population's genetic makeup.

D) It ensures that the population size remains constant.

Correct Answer: B

Natural selection affects populations by allowing individuals with favorable phenotypes to survive and reproduce more successfully, which increases the prevalence of those traits in subsequent generations.

The introduction of a new, highly effective predator into an ecosystem represents a change in the biotic environment. What is the most likely impact on a prey population according to the principles of natural selection?

A) The rate of evolution in the prey population will be unaffected.

B) The prey population will go extinct immediately.

C) The direction of evolution will shift, favoring genetic variations that aid in predator evasion.

D) All individuals in the prey population will simultaneously develop new defense mechanisms.

Correct Answer: C

The text states that fluctuations in the biotic environment can affect the rate and direction of evolution. The new predator creates a selective pressure that favors different genetic variations (e.g., camouflage, speed), thus changing the direction of evolution.

Which statement best summarizes a key aspect of natural selection?

A) Individuals with favorable traits are more likely to survive and reproduce.

B) All individuals in a population have an equal chance of reproducing.

C) Environments remain stable to allow for gradual evolution.

D) Reproductive success is determined by an organism's age.

Correct Answer: A

This is a direct summary of the concept from the text: 'individuals with favorable phenotypes are more likely to survive and reproduce.'

The idea that environmental fluctuations can select for 'different genetic variations in each generation' implies that:

A) A trait considered favorable in one generation may not be in another.

B) Evolution is a predictable process with a fixed endpoint.

C) Genetic variation within a population tends to decrease over time.

D) The environment causes specific, needed mutations to occur.

Correct Answer: A

If the environment selects for different variations in different generations, it means the definition of a 'favorable phenotype' is dependent on the current environmental conditions and can change over time.

While natural selection acts on the survival and reproduction of individuals, its long-term evolutionary consequences are measured at what level?

A) The individual organism.

B) The ecosystem.

C) The population.

D) The family unit.

Correct Answer: C

The content specifies that natural selection 'affects populations.' The cumulative effect of individual survival and reproduction leads to changes in the characteristics of the entire population over time.

In a forest where the only available food for a species of squirrel is nuts with very hard shells, which of the following individuals would have the highest evolutionary fitness?

A) A squirrel that is very fast but cannot crack the nuts.

B) A squirrel with slightly stronger jaws that can crack the nuts and produces many offspring.

C) A squirrel that lives for a very long time but is sterile.

D) A squirrel that is large but has weak jaws.

Correct Answer: B

This individual has a favorable phenotype (strong jaws) for the environment, allowing it to survive, and it demonstrates high reproductive success, which is the measure of evolutionary fitness.

A particular genetic variation in a fish population allows for survival in water with low oxygen levels. If an abiotic event like thermal pollution reduces oxygen levels in their lake, what is the expected outcome?

A) The rate of evolution will slow down as the population adapts.

B) All fish will be equally likely to survive the change.

C) The fish with the pre-existing low-oxygen tolerance will have greater reproductive success.

D) The entire fish population will migrate to a new lake.

Correct Answer: C

The abiotic change creates a selective pressure. Individuals with the favorable genetic variation are more likely to survive and reproduce, thus having greater evolutionary fitness and passing that trait on.

Which of the following describes one of the fundamental causes of natural selection?

A) Populations are static and do not change.

B) Resources in any given environment are unlimited.

C) Individuals vary in their phenotypes, and some are more favorable than others.

D) All organisms produce only one offspring.

Correct Answer: C

The concept that individuals have 'favorable phenotypes' that make them 'more likely to survive and reproduce' is a core cause of natural selection. This implies variation exists within the population.

The phrase 'survival of the fittest' is often used to describe natural selection. Based on the provided content, what is the most accurate interpretation of 'fittest'?

A) The individual that is the strongest and most aggressive.

B) The individual that lives the longest life.

C) The individual that is best adapted to the environment and has the most offspring.

D) The individual that is the most intelligent.

Correct Answer: C

The content defines evolutionary fitness by 'reproductive success' and notes that individuals with 'favorable phenotypes' for their environment are more likely to survive and reproduce. Therefore, 'fittest' refers to the one who reproduces the most in a given environment.