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
Water Relations of a CellPermeability : During various biological activities, a large number of substances enter the cell and large amount goes out of cell. This is due to the permeability shown by the cell.Solute : A solute is a substance which is dissolved in a liquid.Solution : A liquid with dissolved solute in it
Organization of tissue of Primary Dicot root : Secondary GrowthGrowth in plants is caused by the activity of the apical meristems present in the apices of stems, branches and roots. The primary structure of the plant is given by apical meristem. Apart from the linear growth, there is a corresponding enhancement in the thickness of
Tissue : The group of cells with more or less similar structure and performing a definite function, is called a tissue.Organs : In most of the complex living beings group of tissues are combined to form organs. Stomach of vertebrate animals is an example of an organ. An organ, therefore, consists of a group of
Morphology : Various branches of botany are studied with the help of external morphology.A typical angiospermic plant is shown in the figure below. The RootRoot : The root is the descending prolongation of radicle which grows downward into the soil. It does not get light. It seeks moisture. It does not contain chlorophyll so does
Ecology : Ecology is concerned with the study of plants and animals in relation to their environment.Ecological SpectrumUnder the heading of ecological spectrum we have to study the following aspects :(1) Populations : In a given area we study plants and animals of one species. In other words population includes individuals of one particular species,
Multicellular organisms are called animals. They may be acellular also. Multicellular animals are heterotrophs. About ten million species of living animals are known. These species are different from each other in shape, size, structure and ways of living. All animals except porifers are motile and are provided with sensory or nervous sytem.Body Organisation of AnimalsBody
Main divisions of Plant kingdom are:1. Algae :(i) Chlorophyta (Green Algae)(ii) Phaeophyta (Brown Algae)(iii) Rhodophyta (Red Algae)2. Bryophyta (Liverworts and Mosses)3. Tracheophyta (Vascular plants)A brief description of these is given below—Algae : Algae have three main divisions, namely—Rhodophyta (red algae), Phaeophyta (brown algae), Chlorophyta (green algae).Algae is divided into three different kingdoms. They all lack
Characteristics of Fungi(1) Fungi are found everywhere. They are mostly terrestrial, but a few are aquatic.(2) These are heterotrophic. They live either as saprophytes, parasites or symbionts.(3) Fungi cells grow as elongated filaments called ‘hyphae’.(4) The cells of Fungi contains the usual, cell organelles, all similar to eukaryotes, except plastids. Cell wall is usually made
Protista : It is a kingdom of aquatic unicellular, eukaryotic micro organisms structure of Protista.(i) These are having a typical eukaryotic structure with a membrane bound nucleus.(ii) The cytoplasm of this kingdom has number of membrane bound organelles like mitochondria, golgi complex, endoplasmic reticulum, chloroplasts etc.(iii) Some protista for locomotion have flagella or cilia.(iv) The