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Difficulty: MediumEvidence for Evolution: Comparative Biochemistry and Biogeography

In comparative serology, a higher degree of precipitation resulting from a reaction between human antiserum and the blood serum of another mammal indicates a more distant evolutionary relationship to humans.

Answer: Answer

Answer

False. A higher degree of precipitation in comparative serology indicates greater molecular similarity and therefore a closer evolutionary relationship.
The statement is false. In comparative serology, human antiserum produces the greatest amount of precipitate when mixed with serum from closely related primates (such as chimpanzees) because their serum proteins are nearly identical in structure to human serum proteins. The amount of precipitate decreases as the evolutionary distance between the species increases.

Step-by-Step Solution

1
Recall the biochemical principles behind comparative serological testing.
Antibodies produced against human serum proteins bind to homologous serum proteins present in other species, forming an insoluble precipitate.
Organisms that share a recent common ancestor possess proteins with similar amino acid sequences and antigenic determinants.
2
Relate the amount of precipitate to evolutionary similarity.
A larger volume of precipitate indicates a higher percentage of shared protein structures and greater immunological cross-reactivity.
More matching epitopes allow more antibody-antigen complexes to form and precipitate out of solution.
3
Evaluate the claim made in the statement.
The statement incorrectly claims that higher precipitation corresponds to a more distant evolutionary relationship.
Higher precipitation directly correlates with closer evolutionary kinship, making the statement false.

Key Concept

Comparative Serology as Evidence for Evolution
Estimated Time:1m 0s
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Topics

Evidence for Evolution: Comparative Biochemistry and Biogeography

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