Question 1

A genetic change that caused a certain Hox gene to be expressed along the tip of a vertebrate limb bud instead of farther back helped to make possible the evolution of the tetrapod limb. This type of change is illustrative of

Accepted Answer

This genetic change is a clear example of a change in a developmental gene or its regulation that resulted in a modification in the spatial organization of body parts, in this case, the development of a limb. This is known as heterotopy, which refers to a mutation that changes the location of gene expression within an organism's developmental program.

Question 2

A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from lungs of an ancestral fish is an example of

Accepted Answer

The swim bladder evolved from the lungs of an ancestral fish, which is an example of exaptation. Exaptation is the process by which a structure or behavior that evolved in one context is used for a different function. In this case, the lungs of an ancestral fish were not initially evolved for buoyancy, but were later adapted for that purpose.

Question 3

Adaptive radiations can be a direct consequence of four of the following five factors. Select the exception.

Accepted Answer

Genetic drift is a random process that can result in changes in the frequency of alleles in a population, but it is not a factor that directly leads to adaptive radiations. The other four factors (vacant ecological niches, colonization of an isolated region with suitable habitat and few competitors, evolutionary innovation, and an adaptive radiation in a food source) can all provide opportunities for rapid diversification of a group of organisms through natural selection.

Question 4

Which of the following steps has not yet been accomplished by scientists studying the origin of life?

Accepted Answer

Formation of protobionts that use DNA to direct the polymerization of amino acids has not yet been accomplished by scientists studying the origin of life. While there have been efforts to create protobionts and ribozymes that can synthesize RNA and peptides, DNA-directed protein synthesis has not yet been achieved.

Question 5

Use the unlabeled clock diagram below to test your memory of the sequence of key events in the history of life on Earth described in this chapter by labeling the colored bars. As a visual aid to help you study, add labels that represent other significant events discussed in the chapter, such as the Cambrian explosion, origin of mammals, and Permian and Cretaceous mass extinctions.

Accepted Answer

The answer of Use the unlabeled clock diagram below to...

Quiz 25: The History of Life on Earth

A genetic change that caused a certain Hox gene to be expressed along the tip of a vertebrate limb bud instead of farther back helped to make possible the evolution of the tetrapod limb. This type of change is illustrative of

A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from lungs of an ancestral fish is an example of

Adaptive radiations can be a direct consequence of four of the following five factors. Select the exception.

Which of the following steps has not yet been accomplished by scientists studying the origin of life?