When the sperm meets the egg during sexual reproduction, a zygote is formed. this single-cell zygote is the first step of a much more complex multi-cellular organism.

The reactions that occur in the ribosome, where amino acids are combined to form proteins are anabolic or catabolic?

Veins have a much lower blood pressure than arteries. which of these prevents backflow of blood in veins? a. pressure applied by the heart b. one–way valves in veins c. thin muscular walls of veins

The greenhouse effect a. something that has occurred for millions of years b. an unnatural phenomenon caused by humans that maintains earths temperature range. c. the results of the differences in the angle of the suns rays d. an unnatural phenomenon that causes heat energy to be radiated back into the atmosphere