Biology

Exocrine and Endocrine glands : These glands are secretory sites of the body. They are of two kinds—the exocrine and the endocrine glands. The exocrine glands convey their secretion to the place of their action via ducts whereas the endocrine glands secrete the active chemical messengers, the hormones and pour their secretion into the blood […]

Every living organism is sensitive and responds to changes in the external and internal environment of the body. The external and internal stimuli are received by varied types of receptors or sense organs. Every sense organ is supplied with the sensory nerve fibres which convey these stimuli to the C.N.S. These sense organs are grouped

Nervous system is responsible for complete control and co-ordination of the body and mind.Co-ordination : For the evolution of multicellular organism, it became absolutely necessary to develop certain system which may co-ordinate the functions among the different cells tissues and organs and may exchange the information between the changes in external environment and internal cellular

Skeleton systems are of following two types—Exoskeleton : This system remains on the surface of the body such as scales in fishes; wings, claws and feathers in birds; hair, teeth, horn and nail in mammals.Endoskeleton : This provides the main base and shape to the man. It is made up of bone and cartilage.Bones(a) Replacing

Nutrition : Nutrition is defined as the process in which breakdown of complex food materials into simpler substances and its subsequent absorption in the body takes place.Nutrients : The organic and inorganic substances which the living organism collects from the nature to carry out all the basic activities of the body are called nutrients.Minerals :

Locomotion : It is the act of movement which includes walking, running, crawling, hoping, flying or swimming freely, either on land or in liquid or in gaseous medium.Movement : It refers to the act of certain parts of the body in a particular direction.Types of muscle fibres(i) Skeletal muscle fibres.(ii) Smooth muscle fibres.(iii) Cardiac muscle

Excretion : It is the process that eliminates the waste products formed beacause of anabolism and catabolism of the body. Excretion involves the removal of nitrogeneous waste products from the body.Various waste products :Ammonia, urea, uric acid, bile pigments, excess salts and water are the waste products.Excretory organs : These are the organs which are

Circulatory System : It is a closed system of heart, arteries and veins which are used for transporting the blood to all parts of the body.Blood: It is a liquid connective tissue present in blood vessels inside the body. In its plasma the blood corpuscles or cells are floating.Plasma : It is a yellow straw

Respiration : Respiration is the process which involves the oxidation of food substances in the body to release energy. It is very important process.In respiration, there occurs exchange of gases, oxygen and carbon dioxide, between the body and the outside environment.Respiratory System : The various organs required for gaseous exchanges are said to form a

Enzymes : Enzymes are biocatalysts that accelerate the rate of biological reactions in our body. All reactions in the process of digestion of food are brought about by enzymes. They are similar to catalyst in chemistry in their action.Digestion : It is a hydrolytic process and is carried out by a number of enzymes. Digestion

Animal tissue : There are four types of tissue found in higher animals. These are: (i) epithelial tissue, (ii) connective tissue, (iii) muscular tissue and(iv) nervous tissue.Epithelial tissue : Epithelial tissues are those tissues that form the covering of outer and inner surfaces of various organs of the body. These tissues generally serve as a

Growth : Growth is an irreversible process for all living beings which is commonly accompanied by increase in size, weight and volume of the organism till maturity. In plants generally it takes place by the activity of apical, intercallary and lateral meristems.Cellular growth of every living organism involves three main aspects called phases of growth.(i)

Reproduction : Reproduction is the process in living organisms to produce more organisms exactly like themselves.Asexual reproduction : The process by which reproduction takes place without the fusion of gametes is called asexual reproduction.Zoospores : Zoospores are the motile spores provided with cilia or flagella and which can swim freely in water e.g., Ulothrix, Vaucheria,

Photosynthesis :(i) It is an anabolic process.(ii) Photosynthesis is a constructive process which forms new cell wall substances.(iii) Dry weight of plant increases.(iv) Energy is stored in the form of potential energy in glucose molecules. (1 mol of glucose C6H12O6 contains 686 kcal of energy).(v) Water, CO2 etc. produce glucose which is a complex material.

Plants are autotrophic. They need inorganic substances from outside and synthesize their own organic elements. Materials needed by the plant are chiefly obtained from the soil where they are present in the form of minerals. They are called mineral nutrients. Such a nutrition is called mineral nutrition. The criteria as to which elements should be