Q.5RQ. - Biology

Question

Some animals use diffusion instead of a circulatory system. Examples include: 

a. birds and jellyfish 

b. flatworms and arthropods 

c. mollusks and jellyfish 

d. none of the above

Step-by-Step Solution

Answer

Diffusion is used by some animals instead of a circulatory system. None of the above are examples.

As a result, the correct option is (d).

This is due to the fact that birds, jellyfish, flatworms, arthropods, mollusks, and jellyfish all have a circulatory system.

Step 1: Introduction

1. Diffusion helps some animals to exchange water, nutrients, and gases in an efficient way. 
2. This process is helpful for animals containing very thin cell layers. 
3. But a complex organism needs a circulatory system for the transportation of materials.

Step 2: Explanation of the correct option

• The animals which use the diffusion process are jellyfish and sponges. 
• The cell walls of these are very few layers thick so they can easily use diffusion for the exchange of nutrients.
• Hence, the correct option is (d).

Step 3: Explanation of the incorrect options

• Birds have a closed circulatory system. In this, the blood is pumped by the heart through blood vessels. 
• Jellyfish use diffusion to exchange fluids. 
• Hence, option (a) is incorrect. 
• Flatworms do not breathe from the lungs, so they do not require any sort of circulatory system. 
• They breathe through their skin, and oxygen gas is transported with the help of diffusion. 
• Arthropods have an open circulatory system. 
• Hence, option (b) is incorrect.  
• Mollusks use an open circulatory system for the transportation of materials throughout their bodies. 
• Hence, option (c) is incorrect.