As water vapor , the water droplets in the air grow heavier. Water falls from clouds in the form of , , , or hail.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products

the most common type of reef is the fringing reef. this type of reef grows seaward directly from the shore. they form borders along the shoreline and surrounding islands.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.

in addition to being able to metabolize, grow, digest food, and excrete wastes, what other functions must an organism perform if it is to survive? survival also depends on the ability to maintain one's boundaries, to move, to respond to stimuli, and to reproduce. oxygen is a survival need.