Pome. A type of fruit characteristic of apples and pears. The flesh of the fruit develops from the receptacle of the flower, which completely encloses the fused carpels. After fertilization the carpels form the core of the fruit, which contains the seeds.

Pons. (pons Varolii). A thick tract of nerve fibres in the brain that links the medulla oblongata to the midbrain. Its function is to relay impulses between different parts of the brain.

Population. (in ecology). 1. 1. A group of individuals of the same species within a community. The nature of a population is determined by such factors as density, sex ratio, birth and death rates, migration, and immigration. (2) The total number of individuals of a given species or other class of organisms in defined area, e.g. the population of cows in India.

Pore. Any small opening in the skin or epidermis or any structure.

Portal vein. Vein carrying blood from a capillary network to another.

Porrect. Extending outward and forward.

Important technique in diagnosis of human pathogens and plant pathogenic viruses and the basis for serological identification of micro-organisms in general.

Precocial young. Mammals or birds born in a partially independent condition.

Preadaptation. The possession by an organism of characteristics that permit a move into a new Niche or habitat.

Predator. Animal that feed on other animals, i.e. is a secondary consumer; but excluding  a parasite.

Preformation. Hypothetical pre-existence of entire adult diversity of structure in the fertilized egg; embryonic development supposedly consisting merely of enlargement and manifestation of this structure.