Question 1

Which of the following best describes the Biological Species Concept?

Accepted Answer

A group of populations that are reproductively isolated from other such groups and can interbreed in nature.

Question 2

A botanist discovers a new plant species that reproduces only by cloning itself. Which limitation of the Biological Species Concept is most relevant in this scenario?

Accepted Answer

It cannot define species boundaries among asexually reproducing organisms.

Question 3

Two closely related bird species live in the same forest, but one sings at dawn and the other at dusk. Which isolating mechanism is responsible for preventing interbreeding?

Accepted Answer

Temporal isolation

Question 4

A researcher observes that the sperm of one sea urchin species cannot fertilize the eggs of another, even though they are released into the same water at the same time. What is the specific reproductive barrier at work?

Accepted Answer

Gametic incompatibility

Question 5

Which of the following is an example of postmating reproductive isolation?

Accepted Answer

A horse and a donkey mate to produce a mule, which is sterile.

Question 6

Why do postmating barriers, such as hybrid inviability or infertility, impose an evolutionary cost?

Accepted Answer

They result in wasted reproductive effort, as offspring cannot survive or reproduce.

Question 7

Which scenario best illustrates allopatric speciation?

Accepted Answer

A population of insects splits into two groups after a river forms, and each group evolves independently.

Question 8

Polyploidy is a common mechanism of speciation in plants. Which statement best explains why polyploidy can lead to instantaneous speciation?

Accepted Answer

Polyploid individuals cannot interbreed with the original population due to differences in chromosome number.

Question 9

Which of the following is NOT a condition that typically promotes adaptive radiation?

Accepted Answer

A stable environment with little ecological change.

Question 10

A population of beetles is split by a newly formed canyon. Over generations, each group accumulates different mutations. Which evolutionary process is primarily responsible for their divergence?

Accepted Answer

Genetic drift

Question 11

Which of the following best explains why species with highly specialized diets are at greater risk of extinction?

Accepted Answer

They cannot survive if their specific food source disappears.

Question 12

A small population of birds colonizes a remote island with many unoccupied niches. Over time, this population evolves into several distinct species, each adapted to a different food source. What is this process called?

Accepted Answer

Adaptive radiation

Question 13

Which of the following is the primary driver of contemporary extinction events?

Accepted Answer

Habitat destruction

Question 14

A population of fish in a lake is divided by a dam, preventing gene flow. After many generations, the two groups can no longer interbreed even if the dam is removed. Which process has occurred?

Accepted Answer

Allopatric speciation

Question 15

Which of the following equations best represents the probability $$P of $$two populations remaining genetically identical after $$n$$ generations, assuming no gene flow and random mutation rate $$\mu$$ per generation?

Accepted Answer

$$P = (1 - \mu)^n$$

Question 16

Which scenario best illustrates ecological isolation as a premating barrier?

Accepted Answer

Two species of lizards live in the same region, but one inhabits trees while the other lives on the ground.

Question 17

A liger is the offspring of a male lion and a female tiger. Although ligers are healthy, they cannot produce offspring. Which reproductive barrier does this illustrate?

Accepted Answer

Hybrid infertility

Question 18

Which of the following is a real-world example of temporal isolation?

Accepted Answer

Two species of orchids release pollen at different times of day, preventing cross-pollination.

Question 19

Which of the following best explains why morphological similarity is not always a reliable indicator of species boundaries?

Accepted Answer

Organisms that look alike may not interbreed, and those that look different may belong to the same species.

Question 20

A species of snail is found only on a single small island. Which factor makes this species especially vulnerable to extinction?

Accepted Answer

Localized distribution

The Origin of Species: Mechanisms, Speciation, and Extinction

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