Question 19 - MCQs from NCERT Exemplar - Chapter 6 Class 10 - Life Processes

Single circulation i.e., blood flows through the heart only once during one cycle of passage through the body, is exhibited by

(A) Labeo, Chameleon, Salamander

(B) Hippocampus, Exocoetus, Anabas

(C) Hyla, Rana, Draco

(D) Whale, Dolphin, Turtle

Answer

The organisms which have a two chambered heart show single circulation.

This means that blood flows through the heart only once during one cycle of circulation in the body.

Usually the aquatic organisms have two-chambered hearts.

Now, let’s go through the options:

• Labeo, Chameleon, Salamander- While labeo is a fish, chameleon is a reptile and salamanders are amphibians both with 3 chambered hearts . Hence this is not the correct option
• Hippocampus, Exocoetus, Anabas- Hippocampus, Exocoetus and Anabas are all aquatic animals . Hence they have 2 chambered hearts and exhibit single circulation . 
• Hyla, Rana, Draco- Hyla, Rana, Draco are all different species of Frogs , which are amphibians and have 3 chambered hearts and  hence do not exhibit single circulation. 
• Whale, Dolphin, Turtle- Whales and Dolphins are mammals meaning they have 4 chambered hearts, while turtles are reptiles . They have 3 chambered hearts . Hence none of these exhibit single circulation. 

So, the correct answer is (b) Hippocampus (sea horse), Exocoetus and anabas