Question

Vestigial structures are anatomical structures a. that have more than one function. b. that were functional in an ancestor but no longer have a useful function. c. that look similar in different species but have different functions. d. that have the same function in different species but have very different appearances. e. of the body wall.

Short answer

The correct answer to this multiple-choice question would be 'b. that were functional in an ancestor but no longer have a useful function.'

Step-by-step solution

Understand the term Vestigial Structures

Vestigial structures are parts of the body that are remnants of structures which had important functions in ancestral species but are no longer needed or functional. They don’t have a current function in the organism and are considered evidence of evolution.

Compare definition with the answer choices

In this step, the definition of Vestigial Structures would be matched with each option to see which one aligns best with the vestigial structures' definition.

Select appropriate answer

Now that the comparison with each definition has been made, choose the option that best matches the definition of vestigial structures. In this case, that would be option 'b. that were functional in an ancestor but no longer have a useful function.'

Key concepts

Anatomical Structures

Anatomical structures refer to the various parts and components that make up an organism's body. These include organs, tissues, bones, and other structures. The study of anatomy helps us understand how bodies are built and how they function. Some anatomical structures are crucial for survival, performing essential roles in various biological processes. Other anatomical structures, like vestigial structures, might not have a clear function. They offer insights into the evolutionary past of a species.

Vestigial structures are a fascinating example of anatomical structures that historically played important roles but have lost their original function. For example, the human appendix is considered vestigial. It is believed to have been part of the digestive system in ancestral species. Although less critical now, these structures are crucial to our understanding of evolutionary biology.

Evidence of Evolution

Vestigial structures serve as significant evidence of evolution, showcasing a lineage of common ancestry. The presence of these structures illustrates that organisms have remained connected through evolutionary changes over millions of years. This concept supports Charles Darwin's theory of natural selection and adaptation.

Consider the example of a whale's pelvis. These marine mammals have vestigial pelvic bones, a remnant from land-dwelling ancestors. Although whales no longer require these structures for walking, their presence highlights evolutionary transitions from land to water.

• Similar transitional evidence is seen in snakes, where the tiny remnants of hind limbs are indicative of their four-legged ancestors.
• Vestigial wings in flightless birds like ostriches demonstrate the loss of certain abilities as dictated by evolutionary pressures.

Ancestral Species

Ancestral species are the predecessor organisms from which modern-day species have evolved. These ancestors exhibit characteristics that have been passed down, modified, or sometimes lost through millions of years. Understanding ancestral species helps us decipher the evolutionary paths of current organisms.

Vestigial structures serve as clues in tracing back to ancestral species. By studying these structures, scientists can make inferences about the lifestyle and environment of these ancestors. For example, the vestigial tailbone in humans suggests our ancestors had tails, which were perhaps useful in a different ecological niche.

The process of evolution might render some ancestral traits unnecessary in new environments, leaving behind vestigial remnants. Such remnants illustrate the story of survival and adaptation aligned with the changing needs of descendants over time.