Question

Which among the following has an open circulatory system?

• A. i and ii
• B. iii and iv
• C. i and iii
• D. ii and iv

Answer 1

The correct option is A

i and ii

The correct option is A.

Explanation for correct answer:

Option A:

1. The open circulatory system refers to the circulatory system in which the body fluid runs openly through the body.
2. In this system, the body fluid is hemolymph instead of blood. Such organisms lack a closed system and have a hemocoel.
3. The hemocoel is a central body cavity that is found in invertebrate animals and has arteries that are open.
4. Arthropods have an open circulatory system that pumps blood into the hemocoel. The blood is a mix of blood and interstitial fluid known as the hemolymph.
5. Molluscs have an open circulatory system in which the hemolymph is transported via sinuses that lack epithelial walls.

Explanation for incorrect answer:

Option B:

1. Annelids have a close circulatory system. The blood is circulated through blood vessels and capillaries.
2. Coelenterata lacks a specialized circulatory system as they rely on diffusion for the transport of particles. Their circulatory system is a closed type.

Option C:

Annelids have a close circulatory system. The blood is circulated through blood vessels and capillaries.

Option D:

Coelenterata lacks a specialized circulatory system as they rely on diffusion for the transport of particles. Their circulatory system is a closed type.

Final answer: Arthropoda and Mollusca have an open circulatory system.