Problem 4 - Campbell Biology

Question

DNA sequences in many human genes are very similar to the sequences of corresponding genes in chimpanzees. The most likely explanation for this result is that (A) humans and chimpanzees share a relatively recent common ancestor. (B) humans evolved from chimpanzees. (C) chimpanzees evolved from humans. (D) convergent evolution led to the DNA similarities.

Step-by-Step Solution

Answer

A

Step 1: Understand the Question

Identify the relationship between the DNA sequences of humans and chimpanzees based on genetic similarities.

Step 2: Analyze the Options

Read and analyze each of the provided explanations: (A) humans and chimpanzees share a relatively recent common ancestor. (B) humans evolved from chimpanzees. (C) chimpanzees evolved from humans. (D) convergent evolution led to the DNA similarities.

Step 3: Eliminate Incorrect Options

Determine which options do not logically explain the similarity in DNA sequences. (B) is incorrect because humans did not evolve directly from chimpanzees. (C) is incorrect because chimpanzees did not evolve directly from humans. (D) is incorrect because convergent evolution typically leads to similar traits, not similar DNA sequences.

Step 4: Select the Most Likely Explanation

Option (A) states that humans and chimpanzees share a relatively recent common ancestor. This is the most supported explanation based on evolutionary biology.

Key Concepts

Common Ancestor

Humans and chimpanzees share a common ancestor. This means that a long time ago, there was a population of organisms that eventually gave rise to both species. Over time, these species evolved in different directions.
However, because they both originated from this common ancestral population, they still share many similarities in their DNA sequences.
A common ancestor is a key concept in understanding the genetic similarities between different species.
This concept is central to the study of evolutionary biology, as it helps explain why we see patterns of similarities and differences in the biological world.

Evolutionary Biology

Evolutionary biology is the study of how life changes over time. It helps us understand why species look and behave the way they do today.
One essential idea in evolutionary biology is that all life on Earth is related. Through a process called evolution, species adapt to their environments. This leads to the diversity we see today.
Natural selection is a major mechanism of evolution. It acts on the genetic variation within a population, favoring traits that improve reproductive success.
By studying evolutionary biology, scientists can trace the lineage of organisms and determine how different species are connected through common ancestors.

DNA Sequence Comparison

DNA sequence comparison is a method used to examine the genetic material of different organisms. By comparing the sequences of DNA, scientists can determine how closely related different species are.
Humans and chimpanzees have very similar DNA sequences. About 98-99% of our DNA is identical to that of chimpanzees. This high level of similarity is evidence of our close evolutionary relationship.
DNA comparison is an important tool in genetics and evolutionary biology. It helps us uncover the history of life on Earth and understand the genetic basis of biology.

Genetic Similarity Explanation

The genetic similarity between humans and chimpanzees can be best explained by our shared ancestry. When species share a common ancestor, they inherit similar genetic material from that ancestor.
As generations pass, mutations and natural selection cause some genetic differences to accumulate. However, many parts of the DNA remain very similar, reflecting the shared history of the species.
This is why we can see such high levels of similarity between human and chimpanzee DNA. It is a testament to our recent common ancestor and the evolutionary processes that shaped both species.