NCERT Class 11 Science — Chapter 5: Body Fluids and Circulation

mcqeasy

Unlike most reptiles, crocodiles possess a heart with:

Official previous-year question

Verified 1 Aug 2026.

Options

A5 chambers
B4 chambers
C2 chambers
D3 chambers

Did you get this right?

Solution

The correct option is 4 chambers.

Explanation

The evolution of the vertebrate heart involves a transition from a simple two-chambered structure to a complex four-chambered system. This evolution allows for the efficient separation of oxygenated and deoxygenated blood, which is crucial for sustaining higher metabolic rates.

Detailed Analysis:

Fish: Possess a 2-chambered heart (one atrium and one ventricle).
Amphibians: Possess a 3-chambered heart (two atria and one ventricle).
Reptiles (General): Most reptiles possess a 3-chambered heart consisting of two atria and one partially divided ventricle. The interventricular septum is incomplete, allowing some mixing of blood.
Crocodiles: Crocodiles are a significant exception among reptiles. They possess a 4-chambered heart with two distinct atria and two distinct ventricles, separated by a complete septum. This structure prevents the mixing of oxygenated and deoxygenated blood within the heart, similar to birds and mammals.

Key Takeaway:
While the typical reptilian heart is 3-chambered with an incomplete septum, crocodiles uniquely possess a 4-chambered heart.

Your note

More from Chapter 5: Body Fluids and Circulation

Consider the following statements about the ABO blood grouping: 1. It is based on surface antigens A and B on white blood cells. 2. Plasma contains natural antibodies against absent antigens. 3. Blood transfusion requires matching of blood groups. Which of the statements given above are correct?

medium

Which structural feature characterises mature mammalian RBCs?

medium

Assertion (A): The spleen is often referred to as the "graveyard of RBCs". Reason (R): The spleen acts as a filter of the blood, trapping blood-borne microorganisms.

medium

Consider the following statements regarding plasma: 1. It constitutes nearly 55% of blood. 2. Water forms about 90-92% of plasma. 3. Plasma proteins contribute around 6-8%. 4. Serum is plasma with clotting factors. Which of the statements given above are correct?

medium

Where are human Red Blood Cells (RBCs) primarily formed in adults?

medium

Keep practising Chapter 5: Body Fluids and Circulation

Work through every question from this NCERT chapter.

Browse all NCERT Class 11 Science chapters

The correct option is 4 chambers.

Explanation

Detailed Analysis:

Fish: Possess a 2-chambered heart (one atrium and one ventricle).
Amphibians: Possess a 3-chambered heart (two atria and one ventricle).
Reptiles (General): Most reptiles possess a 3-chambered heart consisting of two atria and one partially divided ventricle. The interventricular septum is incomplete, allowing some mixing of blood.
Crocodiles: Crocodiles are a significant exception among reptiles. They possess a 4-chambered heart with two distinct atria and two distinct ventricles, separated by a complete septum. This structure prevents the mixing of oxygenated and deoxygenated blood within the heart, similar to birds and mammals.

Key Takeaway:
While the typical reptilian heart is 3-chambered with an incomplete septum, crocodiles uniquely possess a 4-chambered heart.