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Difficulty: EasyVertebrates: Poikilothermic Classes (Pisces, Amphibia, Reptilia)

Which of the following circulatory structures is characteristic of the heart in an adult amphibian, such as a toad?

  1. A
    A two-chambered heart consisting of one atrium and one ventricle
  2. A three-chambered heart consisting of two atria and one ventricleAnswer
  3. C
    A four-chambered heart with completely divided ventricles
  4. D
    A single tubular heart without distinct internal chambers

Answer

A three-chambered heart consisting of two atria and one ventricle
The heart of an adult amphibian consists of three chambers: a right atrium that receives deoxygenated blood from the body, a left atrium that receives oxygenated blood from the skin and lungs, and a single ventricle that pumps blood out.

Step-by-Step Solution

1
Identify the taxonomic class of the subject organism
The toad belongs to the poikilothermic vertebrate class Amphibia.
Knowing the taxonomic class establishes the fundamental structural organization of the circulatory system.
2
Determine the heart chamber structure for adult amphibians
Adult amphibians have a 3-chambered heart (left atrium, right atrium, and one ventricle).
Deoxygenated blood enters the right atrium while oxygenated blood enters the left atrium, both emptying into a single ventricle.

Key Concept

Heart chamber configuration across poikilothermic vertebrate classes (Pisces: 2 chambers; Amphibia & Reptilia: 3 chambers).
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Topics

Vertebrates: Poikilothermic Classes (Pisces, Amphibia, Reptilia)

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