Halogen

Highly reactive gases forming group 7 of the periodic table.

Fly-By

The passage of a spacecraft near a planet, a moon or an asteroid.

Competent

Able to take up exogenous DNA and thereby be transformed.

Equilibrium

A stable situation in which products and reactants are balanced.

Homogenous Matter

Matter which is uniform in appearance and composition throughout.

Spermatid

The four products of meiosis in males that develop into sperm.

Clinal Selection

Selection that changes gradually along a geographic gradient.

Bias

Any factor that causes distortion of genetic predictions.

Categorical Trait

A trait in which phenotypes are expressed in categories.