A serological reaction in which an anti-serum is reacted against an antigen other than the one used in its preparation. Heterophile reaction Antigen-antibody reaction, in which the antibody was not specifically elicited by the antigen to which it binds. Heterosis Increased growth, vigour or yield frequently shown in the F1 generation of a cross. The condition in which fungi produce compatible male and female gametes on physiologically distinct mycelia. Heterotrophic Refers to organisms that are dependent upon outside sources for growth, being incapable of synthesising required organic materials from inorganic sources.
Heterotrophs obtain their food from other organisms, living or dead.
Heteroxenous Living within more than one host during a parasite's life. Heterozygous Having a dominant and a recessive gene of a pair in the same cell or organism. An organism can be heterozygous for one or several genes. High-volume See spray vii. Hilum The scar on a seed which marks the point of its attachment to the pod or seed stalk.