The below mentioned article provides notes on plants and animals.
Man has always been impressed by the vastness and variety of living things. Life manifests itself in infinite numbers and diverse forms. Leaving aside the less known and submicroscopic viruses, the plants and animals are the two important kinds of living things.
Man himself is an animal, and so too are the hairy mammals, feather-clad birds, scaly reptiles, warty toads and the finned fishes (Fig. 9). The oysters, butterflies, starfishes, earthworms, roundworms, tapeworms, corals, sponges and the microscopic creatures that cause malaria in man are also animal (Fig. 10).
Familiar plants are those that yield maize, pea, mustard, tuberose, prickly pear, cocoanut palm and cycad (fig .11).Ferns mosses, liverworts, lichens, mushrooms, sea-weeds and pond-scums are also plants (Fig. 12).
The lowly microscopic forms such as green Chlamydomonus the colourless yeast, and the enormous assemblage of bacteria are plants too, which have interested man since Leeuwenhoek (1632-1723, Fig. 13) discovered them in the later part of the seventeenth century.
Why should plants and animals assume so many forms? Why should there be such wide variations in size, colour, shape, internal structure and mode of life? The only answer to this question can be found in the adaptation of each kind to the particular environment in which it lives.
Plants and animals are adapted perfectly to their own surroundings. This is effected by modification of forms and habit. They have to find their food and avoid their respective enemies. Failure to do this means extinction of the whole race.
The Indian leaf- butterfly Kallima is eaten by birds. They avoid their enemy by imitating the form and pattern of a leaf while resting on the twig of a plant (Fig. 14). Such phenomenon is very common in the living world and is known as mimicry.
Biology is a vast science. There has been a steady, yet rapid increase of knowledge about organisms during the last one hundred years. It is well-nigh impossible today for a single individual to be acquainted with the diverse aspects of modern biology in minute details.
For the sake of convenience, the science of life has been divided into botany and zoology. Botany (botane = a herb) deals with plants and zoology (zoon = an animal) is concerned with animals.
These two main branches are further subdivided into a number of sub-sciences according to the nature and kind of plants and animals that are involved. Thus bacteriology (bacterion = a little rod) is a branch of botany related to the study of microbes and entomology (entomon = an insect) is a part of zoology devoted to the insects.
Likewise, anthropology (anthropos—a man) is a special section of biological science which discusses the various races of mankind.
Higher plants are readily distinguished from higher animals but the distinction is not so sharply marked in some lowly organisms. For instance, the corkscrew-shaped microscopic Spirochaetes are claimed by the botanists as plants and by the zoologists as animals.