Campbell Biology Terms

Just the glossary

5′ cap

A modified form of guanine nucleo-tide added onto the 5′ end of a pre-mRNA molecule.

ABC hypothesis

A model of flower formation identifying three classes of organ identity genes that direct formation of the four types of floral organ.

abiotic

Nonliving; referring to the physical and chemical properties of an environmen

abortion

The termination of a pregnancy in progress

abscisic acid (ABA)

A plant hor-mone that slows growth, often antagonizing the actions of growth hormones. Two of its many effects are to promote seed dormancy and facilitate drought tolerance

absorption

The third stage of food processing in animals: the uptake of small nutrient molecules by an organism’s body.

absorption spectrum

The range of a pigment’s ability to absorb various wavelengths of light; also a graph of such a range.

abyssal zone