Question

Which of the following organisms has the highest heart rate?
(a) Elephant
(b) Whale
(c) Man
(d) Mouse

Answer 1

Hint: As a general observation, it is seen that the number of beats in an organism is inversely proportional to its size i.e. smaller the animal higher is the heart rate, and the larger the animal lower is the heart rate.

Complete answer:
The mouse has the highest heart rate. A heartbeat defined as one complete cycle of contraction and relaxation of both ventricles. The number of times the heart of an animal beats in a minute is called its heart rate. Heart rate in a normal adult human is 72 beats per min i.e. heart if a normal adult human beats 72 times in a minute. The heart rate of an elephant is 25-35 beats per minute, that of a whale is 10-30 beats per minute and for a mouse, it is 450-750 beats per minute.
Heart rate is usually equal or close to the pulse which is measured from the radial artery. In a normal adult human, if the heart rate rises to 100 beats per minute in resting state, the condition is called Tachycardia. On the other hand, if the heart rate lowers to less than 60 beats per minute at rest, the condition is called Bradycardia. Abnormalities in heart rate are indications of some disorder.
So, the correct answer is ‘mouse’.

Note: Apart from the size of the organism, other factors such as the amount of oxygen present in the atmosphere, physical fitness, diet, drugs, hormonal and metabolic states of the body also have an influence on the heart rate of the organism.