Assertion (A): The spinal nerves are 31 pairs in number.
Reason (R): Spinal nerves only have sensory neurons in them.

P is a cell (or group of cells) in the human body which is sensitive to a particular type of stimulus and conveys the messages to CNS through nerves Q. On the other hand, R is a part of the human body which can respond to a stimulus according to the instructions sent from the CNS through nerves S.

Name the nerves Q.

The two glands A and B which occur in pairs are present in the endocrine system of humans. The pair of glands A is found only in females whereas the pair of glands B occurs only in males. The glands A make and secrete two hormones C and D whereas glands B make and secrete only one hormone E. In addition to hormones, glands A make gametes E whereas glands B make gametes G.

What are hormones C and D?

There are two similar glands P which is located on the top of two similar organs Q in the human body. The glands P are often called glands of emergency, and they secrete a hormone R into the bloodstream. The hormone R is secreted in large amounts when a person is frightened. It brings about temporary changes in the body which allow a lot of substance S from the liver to go into the blood to provide a lot of energy in a very short time. This helps the person concerned to fight back or run away from the frightening situation.

What are P, Q, R and S?

The gland A is attached to the windpipe in the human body. The gland A makes and secretes a hormone B which controls the metabolism of carbohydrates, fats and proteins in the body. The non-metal element C is necessary for the formation of hormone B. The deficiency of C in the diet can cause a deficiency of hormone B in the body leading to a disease D in which the neck of a person appears to be swollen. People are advised to use salt E in cooking food to avoid disease D.

What is the element C? (Iodine/ Calcium/ Magnesium)