Question

Out of the given characters, which ones are present in birds and not mammals?

I- Hollow or pneumatic bones

II- Respiration by lungs

III- Four chambered heart

IV- Absence of teeth

• A. I only
• B. I and II only
• C. I and III only
• D. I and IV only
• E. I, II and III

Answer 1

The correct option is D I and IV only

Hollow or pneumatic bones are present only in birds.

Respiration by lungs occurs in both birds and mammals.

Four-chambered heart is present in both birds and mammals.

Teeth are present only in mammals, not in birds.

So, the features that are present in birds and absent in mammals are hollow bones and absence of teeth. Hence, 'I and IV' is the right option.