Question

Assertion :Medulla is considered as respiratory center in animals. Reason: Rate of breathing is regulated by medulla, because of the changes in $O_2$ content of blood.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Both Assertion and Reason are incorrect.

Answer 1

The correct option is C Assertion is correct but Reason is incorrect.

• The respiratory center is located in the medulla oblongata and pons, in the brainstem. The respiratory center is made up of three major respiratory groups of neurons, two in the medulla and one in the pons. In the medulla, they are the dorsal respiratory group and the ventral respiratory group. Hence, Medulla is considered as the respiratory center in animals.
  
• Medulla oblongata detects the levels of oxygen and carbon dioxide concentrations and signals the muscles in the heart, the lungs and diaphragm to increase or decrease the breathing. The CO2 level is a major regulator of respiration. It is much more important than oxygen to maintain normal respiration. Even very small changes in carbon dioxide levels in the blood cause large increases in the rate and depth of respiration.
  

So, the correct answer is ' Assertion is correct but Reason is incorrect'.