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.

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