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Difficulty: EasyEvolutionary Trends in Plants and Animal Systems

As vertebrates evolved from aquatic habitats to terrestrial environments, their circulatory systems underwent structural adaptations to increase oxygen delivery efficiency. Which of the following correctly compares the heart chambers of fishes and amphibians?

  1. Fishes possess a two-chambered heart, whereas amphibians possess a three-chambered heart.Answer
  2. B
    Fishes possess a three-chambered heart, whereas amphibians possess a two-chambered heart.
  3. C
    Fishes possess a two-chambered heart, whereas amphibians possess a four-chambered heart.
  4. D
    Fishes possess a single-chambered heart, whereas amphibians possess a four-chambered heart.

Answer

Fishes possess a two-chambered heart, whereas amphibians possess a three-chambered heart.
In the evolutionary trend of vertebrate circulatory systems, fishes represent the primitive state with a two-chambered heart (one atrium and one ventricle) that pumps blood through a single circuit. Amphibians represent an intermediate evolutionary stage toward land adaptation, possessing a three-chambered heart (two atria and one ventricle) that supports double circulation.

Step-by-Step Solution

1
Identify the circulatory structure of fishes
Fishes have a 2-chambered heart consisting of one atrium and one ventricle, operating via single circulation.
Aquatic respiration via gills requires a single circuit pump.
2
Identify the circulatory structure of amphibians
Amphibians have a 3-chambered heart consisting of two atria and one ventricle, operating via double circulation.
Transition to lungs and skin for gas exchange requires double circulation to separate oxygenated and deoxygenated blood streams into the heart.
3
Compare the two taxa to determine the correct evolutionary trend
The progression is from a 2-chambered heart in fishes to a 3-chambered heart in amphibians.
Evolutionary complexity increases from lower aquatic vertebrates to higher terrestrial vertebrates.

Key Concept

Evolutionary trends in vertebrate heart chamber complexity
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Topics

Evolutionary Trends in Plants and Animal Systems

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