Unlike dna, rna

a. pairs uracil with adenosine instead of thymine.
b. contains nitrogenous bases.
c. has deoxyribose as the sugar within its nucleotide components.
d. contains two strands wrapped in a helix.

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.

List charasteristics of athenosphere

15 ! come and answer! a(n) is the general term for an infectious disease that has spread across a city, region, or country.