Many scientists classify viruses as non-living. the single, most important reason why viruses are classified as non-living is that they

answer: b)  

are not composed of cells.

explanation:

b. the carbon cycle ensures living things have a source of hydrogen

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