9. a molecule shaped like a spiral staircase (double helix) is a typical of
a. deoxyribonucleic acid
b. ribonucleic acid
d. both a and b
10. ATP is important to living organisms because it
a. stores hereditary information
b. stores energy from food to be used by cells
c. has two extra sugar groups
d. both b and c
11. Which of the following is true about the relationship between energy and chemical reactions?
a. For a chemical reaction to occur, energy must be taken in or given up
b. Energy input is required to carry out a chemical reaction
c. Chemical bonds are always broken by energy absorption in a chemical reaction
d. Energy-absorbing reactions don't occur in chemical reactions
I know it's not d but I'm not sure which one it is...
12. An enzyme
a. is not used up when catalyzing a reaction
b. lowers the activation energy of a reaction
c. bonds with a substrate molecule at the enzyme's active site
d. all of the aboce
13. High magnification and good resolution
a. are different names for the same thing
b. are both needed to make small objects easier to see
c. make the object itself larger
d. both a and b
14. Surface area is an important factor in limiting cell growth because
a. the cells may become too large to remove enough wastes
b. materials cannot enter the cell if it is too large
c. the cell can burst if the membrane becomes too large
d. waste products cannot leave the cell if it is too small