Question

1. What is meant by common ancestry?
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20 points
all organisms have nothing in common
some organisms share similar DNA
only families share similar DNA
all things on Earth share a common ancestor that can be traced back to the earliest form of life.
2. Which of the following are considered homologous structures, and therefore most likely evolved from a common ancestor?
*
20 points
Bird wing and butterfly wing
Cat arm and whale fin
Dolphin fin and shark fin
Bird wing and bat wing
3. What aspect of comparative embryology supports evolutionary theory?
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20 points
All embryos develop differently
Early embryo stages look different across species
Adult organisms always resemble their embryonic form
Early developmental stages are similar among related species
4. What type of evidence do vestigial structures provide for evolution?
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18 points
They show current adaptations
They demonstrate increasing complexity
They represent remnants of ancestral traits
They prove rapid evolution
5. A scientist compares the amino acid sequences of four species to a similar protein produced by a human. The table shows the percentage of similarity in the amino acid sequence of each organism compared to the human sequence.

Organism
Amino acid sequence similarity to human:
Species 1 -85%
Species 2 - 48%
Species 3 -39%
Species 4 -57%

What statement best describes the relationship to humans?
*
20 points
Humans have the most distant evolutionary relationship to Species 4.
Humans have the closest evolutionary relationship to Species 1.
Humans have the fewest common ancestors with Species 1 and 4.
Humans do not have any common ancestors with Species 2 or 3.

Answer 1

1. All things on Earth share a common ancestor that can be traced back to the earliest form of life.
- Explanation: Common ancestry means organisms descend from earlier life forms, ultimately tracing back to a shared origin.

2. Cat arm and whale fin.
- Explanation: Both are modified forelimbs with the same basic bone structure, indicating homology from a common ancestor.

3. Early developmental stages are similar among related species.
- Explanation: Similar embryonic stages among related species reflect shared developmental pathways inherited from common ancestors.

4. They represent remnants of ancestral traits.
- Explanation: Vestigial structures are reduced or nonfunctional features that were functional in ancestors, providing evidence of evolutionary history.

5. Humans have the closest evolutionary relationship to Species 1.
- Explanation: Higher amino acid sequence similarity (85%) indicates a closer evolutionary relationship.