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Transport in animals

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Question 33

An electrocardiogram (ECG) records the electrical activity of the heart over time. The grid on veterinary ECG recordings is calibrated such that 5 large grid squares correspond to exactly 1.0 s1.0\text{ s}1.0 s (meaning each large square represents 0.2 s0.2\text{ s}0.2 s).

The diagram below shows the resting ECG traces of three different mammals:

  • Mammal A: A domestic dog (Canis lupus familiaris), which has a typical resting heart rate between 70 and 120 bpm.
  • Mammal B: A domestic cat (Felis catus), which has a typical resting heart rate between 140 and 220 bpm.
  • Mammal C: A Thoroughbred horse (Equus caballus), which has a typical resting heart rate between 28 and 40 bpm.

Veterinary ECG traces

a.

Calculate the heart rate in beats per minute (bpm) for: (i) Trace P (ii) Trace Q

[3]
b.

Identify which mammal (A, B, or C) corresponds to:

  • Trace P
  • Trace Q
  • Trace R
[3]
c.

Explain how the heart of the Thoroughbred horse (Mammal C) adaptively maintains an adequate resting cardiac output to meet the oxygen demands of its large body mass, despite such a low resting heart rate.

[4]

Transport in animals Questions

  1. A Level
  2. /Biology
  3. /Transport in animals