The energy to sustain intense physical activity is provided mostly by

Carbohydrates

Explanation:

In intense, long-lasting physical activity, the body often uses a balanced blend of fat and carbohydrates (at a higher rate).

The more intense the activity becomes, the more and more muscles tend to use carbohydrate as fuel because it has a faster metabolism. However, they have limited stock (muscle glycogen).

the answers are as following:

1. c. double helix, nucleosome, coil, supercoil, chromosome

2. b. g2 phase, preparation for mitosis

3. d. interphase consists of the g1, s, and g2 phases

4. c. metaphase

5. a. chromosomes are duplicated before cell division so that each new daughter cell has a complete set