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Examine the amino acid sequences from three organisms (A, B, and C). Which two organisms are the most closely related?

Organism A: Val-Ser-Thr-Val

Organism B: Leu-Ala-Leu-Ala

Organism C: Val-Ser-Asp-Met

(1 point)
Responses

B & C
B & C

A & B
A & B

A & C
A & C

They are all equally related.
They are all equally related.

11 answers

To determine which two organisms are the most closely related based on their amino acid sequences, we can compare the sequences for similarities.

  • Organism A: Val-Ser-Thr-Val
  • Organism B: Leu-Ala-Leu-Ala
  • Organism C: Val-Ser-Asp-Met

Looking at the sequences:

  • Organisms A and C share the first two amino acids (Val-Ser), while B has completely different amino acids (Leu-Ala).
  • Organism C has an Asp in the third position instead of Thr from A, but this is still a partial similarity.
  • Organisms A and B do not have any amino acids in common at any position, meaning they are not related based on the sequences provided.

Based on this examination, Organisms A and C are the most closely related due to the similarity in the first two amino acids (Val and Ser).

Therefore, the best response is:

A & C

A scientist is attempting to build a cladogram that shows the evolutionary closeness of three organisms in relation to humans. After doing DNA analysis, they determine that the organisms share the following percentages of DNA:

Organism A and humans share 85% of their DNA.

Organism B and humans share 80% of their DNA.

Organism C and humans share 90% of their DNA.

Based on this information, which order should they go on the cladogram (from least related to most related)?

(1 point)
Responses

C, A, B, humans
C, A, B, humans

C, B, A, humans
C, B, A, humans

A, B, C, humans
A, B, C, humans

B, A, C, humans
B, A, C, humans

To create a cladogram that shows the evolutionary closeness of the organisms to humans based on the percentages of shared DNA, we can analyze the data:

  • Organism A shares 85% of DNA with humans.
  • Organism B shares 80% of DNA with humans.
  • Organism C shares 90% of DNA with humans.

The order of relatedness, from least related to most related, based on DNA similarity is:

  1. Organism B (80% shared DNA) - least related
  2. Organism A (85% shared DNA)
  3. Organism C (90% shared DNA) - most related
  4. Humans

So, the correct order from least related to most related is:

B, A, C, humans

A cladogram shows the evolutionary relationship between humans, chimpanzees, and gorillas. The cladogram currently shows humans and chimpanzees with a more recent common ancestor compared to gorillas. Which piece of evidence, if true, would most likely weaken this hypothesis?(1 point)
Responses

Fossils of humans appear in deeper sedimentary rock layers compared to fossils of chimpanzees.
Fossils of humans appear in deeper sedimentary rock layers compared to fossils of chimpanzees.

The cells of the eye in embryos of gorillas and humans follow a similar pattern of development while chimpanzee embryos are different.
The cells of the eye in embryos of gorillas and humans follow a similar pattern of development while chimpanzee embryos are different.

DNA sequence analysis of the hemoglobin alpha gene shows that humans and chimpanzees have a more similar sequence to each other than they do to the gorilla’s DNA sequence.
DNA sequence analysis of the hemoglobin alpha gene shows that humans and chimpanzees have a more similar sequence to each other than they do to the gorilla’s DNA sequence.

Amino acid analysis of the cytochrome c protein shows significant differences in the sequence of amino acids between humans and gorillas.
Amino acid analysis of the cytochrome c protein shows significant differences in the sequence of amino acids between humans and gorillas.

To assess which piece of evidence would most likely weaken the hypothesis that humans and chimpanzees have a more recent common ancestor compared to gorillas, we need to consider how each piece of evidence affects the relationships proposed by the cladogram.

  1. Fossils of humans appear in deeper sedimentary rock layers compared to fossils of chimpanzees.

    • This evidence would suggest that humans diverged earlier than chimpanzees, potentially supporting the hypothesis in question, rather than weakening it.

  2. The cells of the eye in embryos of gorillas and humans follow a similar pattern of development while chimpanzee embryos are different.

    • This evidence would imply a closer developmental relationship between humans and gorillas than with chimpanzees, which could weaken the hypothesis that humans and chimpanzees are more closely related.

  3. DNA sequence analysis of the hemoglobin alpha gene shows that humans and chimpanzees have a more similar sequence to each other than they do to the gorilla’s DNA sequence.

    • This evidence supports the hypothesis that humans and chimpanzees have a more recent common ancestor since they have more similar DNA than with gorillas.

  4. Amino acid analysis of the cytochrome c protein shows significant differences in the sequence of amino acids between humans and gorillas.

    • This would also suggest a larger evolutionary distance between humans and gorillas, which would not weaken the hypothesis regarding humans and chimpanzees.

Among these options, the second statement—"The cells of the eye in embryos of gorillas and humans follow a similar pattern of development while chimpanzee embryos are different."—would most likely weaken the hypothesis that humans and chimpanzees have a more recent common ancestor compared to gorillas.

Thus, the correct response is:

The cells of the eye in embryos of gorillas and humans follow a similar pattern of development while chimpanzee embryos are different.

The forelimbs of bats and humans have a very similar bone structure even though they appear very different on the outside. These structures are known as __________ because they result from species evolving __________.

Which of the following answer choices correctly completes the above statement?

(1 point)
Responses

analogies; similar adaptations in similar environments
analogies; similar adaptations in similar environments

homologies; from the same common ancestor
homologies; from the same common ancestor

analogies; from the same common ancestor
analogies; from the same common ancestor

homologies; similar adaptations in similar environments
homologies; similar adaptations in similar environments

The forelimbs of bats and humans have a similar bone structure because they both derive from a common ancestry, despite their different appearances and functions. This similarity in structure due to shared evolutionary history is described as homologous structures.

Therefore, the correct completion of the statement is:

homologies; from the same common ancestor.

So the complete statement is:

"The forelimbs of bats and humans have a very similar bone structure even though they appear very different on the outside. These structures are known as homologies because they result from species evolving from the same common ancestor."

All vertebrate embryos have a tail and gill slits at some point during embryonic development. What does this suggest about vertebrates?(1 point)
Responses

These species share a common ancestor.
These species share a common ancestor.

The embryos of these species require these structures to survive.
The embryos of these species require these structures to survive.

These species have the exact same DNA sequence.
These species have the exact same DNA sequence.

These species evolved in similar environments.
These species evolved in similar environments.

The presence of a tail and gill slits in all vertebrate embryos at some point during embryonic development suggests that these species share a common ancestor. This characteristic indicates a shared evolutionary heritage and is an example of embryonic development revealing evolutionary relationships among different species.

Therefore, the correct response is:

These species share a common ancestor.

Fossil A is found closer to the surface compared to Fossil B. Which of the following conclusions can be made based on this statement?(1 point)
Responses

Fossil B is most likely older than Fossil A.
Fossil B is most likely older than Fossil A.

The species of Fossil A existed at the same time as the species of Fossil B.
The species of Fossil A existed at the same time as the species of Fossil B.

The species of Fossil A evolved from the species of Fossil B.
The species of Fossil A evolved from the species of Fossil B.

Fossil A is from an older species than Fossil B.
Fossil A is from an older species than Fossil B.

The principle of stratigraphy states that in undisturbed sedimentary rock layers, the oldest layers (and therefore the oldest fossils) are found at the bottom, and newer layers (and newer fossils) are found closer to the surface. Given that Fossil A is found closer to the surface than Fossil B, it can be concluded that:

Fossil B is most likely older than Fossil A.

This is the most reasonable conclusion based on the provided information.