Why is a DNA molecule called a double helix?
A. Each nucleotide has two main parts: a base and a phosphate.
B. The sugar and phosphate parts are the same in all DNA molecules.
C. There are two kinds of nitrogen bases in a DNA molecule.
D. A DNA molecule always has two strands of nucleotides.

Animal bodies (and even plant bodies for that matter) are complex enough that life couldn't exist without enzymes. enzymes are usually large, complex biological catalysts that are expensive to make. enzymes speed up the rate of chemical reactions without being used up during the reaction (they can be reused many times). they are highly specific in the reactions they regulate. knowing what enzymes are and how they function, why does this explain why complex life forms could not exist if there were no enzymes.

Whay is the following best defines climate

Acceleration is a direct result of a.) balanced forces b.) unbalanced forces c.) gravity d.) velocity