The statements given below have some parts printed in bold face. In case these parts are incorrect rewrite these in correct form.

1. All mammals are ectothermal.
2. Hibernation is also known as summer sleep.
3. Human body temperature normally is 98.6°F (37°C).
4. Vigorous activity in a cold day overheats you.
5. The principal heat-regulating centre is located in the thyroid.
6. Increased body heat causes vasoconstriction.
7. Facial hair in humans contributes to sex differences.

If for some reason the sebaceous glands fail to function:

1. the body will not be able to regulate the body temperature
2. the skin will turn darker with more melanin
3. the hairs will fail to grow
4. the skin will turn dry and rough

Which one of the organs listed below, functions in regulating our body temperature most actively?

1. Heart
2. Lungs
3. Skin
4. Stomach

Sweat glands are situated in :

1. Epidermis
2. Dermis
3. Both
4. None of these