1. Ageing : It is defined as the process which renders individuals more susceptible, as they grow older to various factors, external or internal, which may cause death.
  2. Ape : Largest tailless monkey (Catarrhina : Anthropoidea), a primate most nearly related to man, gibbon (byalobatidae) orangutan; gorilla and chimpanzee (Pongidae). The first two are found in Asia and the last two in Africa.
  3. Artificial selection : It is practiced for production of better varieties of crop plants and domestic animals by selective breeding.
  4. Behavioural isolation : Males of one animal species are unable to recognize the females of its own species as potential mate if kept separate for a long time.
  5. Chimpanzee : Anthropithecus troglodytes an ape, 1.5 metre tall, black coloured confined to central equatorial Africa, builds its abode in trees and is frugivorous.
  6. Closed system : A system in which there is no exchange of materials with the surroundings environment, is a closed system.
  7. Community : All the living organisms belonging to different species in an area, is called community.
  8. Genetic death : A sexually mature individual that is alive but is unable to breed and thus fails to transmit his or her genes to the next generation.
  9. Genetic drift : Random fluctuation of gene frequencies, from generation to generation, that occur in a small population.
  10. Gerontology : The study of ageing is termed gerontology.
  11. Gibbon : Tailless ape, body covered with black fur; face and ear hairless, arms longer than legs. It has seven species. These are found in the forests of Assam (India), Malaysia and Thailand.
  12. Gorilla : Giant ape, Gorilla, largest living anthorpod about two metres tall, having enormous body, long powerful arms and short legs, all covered with black hair, terrestrial and herbivorous, native to western Africa.
  13. Hominidae : Monogeneric family that includes only one species Homo sapiens (Primates, Mammalia, Chrodate). Fully erect posture, head erect with a slender neck, binocular or stereoscopic vision, large brain, legs longer than arms and sole of the foot lies on the ground while walking.
  14. Human being : Homo sapiens, sapiens share a common ancestry with monkeys and apes; evolved 24 million years ago. Bipedal gait and large brain are the distinctive characteristics. Besides, these humans make and use tools, speak particular language(s) and practice prolonged parental care.
  15. Life on other planets : Scientists believe that life may exist on some other planets. There are 1019 stars in the universe which seem to have planets and if only one in a billion planets have the appropriate conditions to mean sustain life, that would mean 1010 planets on which life can exist.
  16. Mammalian evolution : Mammals evolved from primitive reptiles in early Jurassic period (210 million years ago) when dinosaurs dominated the earth. After extinction of dinosaurs (Cretaceous period), mammals started developing and primitive mammals came into being only some 65 million years ago (Teritiary period).
  17. Neanderthal man : Extinct sub-species of man Homo sapiens neanderthalensis, Progeny of the Homo erectus that migrated from Africa and Europe and Asia, lived 500,000 to 30,000 years ago; had protruding face, receding forehead and low domed head. They were adapted to cold environment, fashioned animal skin into clothing.
  18. Open system : A system in which there is a continuous inflow of energy and materials and simultaneous removal of other materials is termed as open system.
  19. Orangutan : Pingo pymageases, large, rare ape, found in forests of Boreno and Sumatra, about 1.5 metre tall, body sparsely covered with long reddish brown hair, arms very long and legs short, aboreal and frugivorous, swinging from branch to branch with their long arms.
  20. Organic evolution : It is a process of change by which the primitive forms of life could develop into more complex forms. It is a continuous, slow and irreversible process of descent with modification.
  21. Photoautotrophic : Organisms which are able to synthesize the carbohydrates in the presence of sunlight.
  22. Population : A group of organism of the same species occupying a particular area.
  23. Primitive life : Unicellular microorganism probably came into being about 3600 million years ago. The earth’s atmosphere at the time was reducing and not oxidizing as it is today.
  24. Spontaneous generation : Theory that life arose from nonliving matter – microorganism from air too water, fish and frogs from mud, while insects were formed from plant juices.