Q5
1 markMCQSection A

Which one of the following statements is correct about the human circulatory system?

Life Processes
Transportation in Human Beings

Options

(A)Blood transports only oxygen and not carbon dioxide.
(B)Human heart has five chambers.
(C)Valves ensure that the blood does not flow backwards.
(D)Both oxygen-rich and oxygen-deficient blood gets mixed in the heart.
Official Answer

The correct option is C.

valvesprevent backflowone-way flow

Marking Scheme

  • 11 mark for selecting the correct option (C).

Hint

Identify the anatomical structures in the circulatory system that act like one-way doors to prevent the backflow of blood.

Quick Oral Answer

Valves ensure that blood flows in only one direction, preventing any backward flow when the heart contracts.

Analysis & Explanation

Option C is correct because valves are specialized muscular structures present in the heart (between atria and ventricles) and in veins. They act as one-way gates to ensure that blood flows only in one direction and does not flow backwards when the heart chambers contract or when blood flows under low pressure.


  • Option A is incorrect because blood transports both oxygen (bound to hemoglobin in red blood cells) and carbon dioxide (mainly in dissolved form in plasma).
  • Option B is incorrect because the human heart has four chambers (two atria and two ventricles), not five.
  • Option D is incorrect because the human heart is completely divided into left and right sides by a muscular septum, which prevents the mixing of oxygen-rich (oxygenated) and oxygen-deficient (deoxygenated) blood to maintain high circulatory efficiency.

Common Mistakes

  1. 1Students sometimes confuse the number of chambers in the human heart with other vertebrates (like amphibians or reptiles which have 3 chambers).
  2. 2Believing that blood only carries oxygen, forgetting that carbon dioxide is also transported by blood back to the lungs.

Interesting Facts

The sound of your heartbeat ('lub-dub') is actually the sound of these heart valves snapping shut!

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2020?

This question carries 1 mark in the CBSE Class 10 Science 2020 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Life Processes" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Transportation in Human Beings" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2020 paper?

This is a MCQ question from Section A in the CBSE Class 10 Science 2020 paper.