Biology

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

Monera : Monera is the most plentiful and smallest living organisms on the earth. These are found everywhere on land. They can be found in hot springs, underside ice bags and on the deep ocean floor, in the hottest and driest deserts as parasites on and in other life forms.Characteristics of Monera1. These are Prokaryotic

Two-Kingdom classification : In 1735, a well-known scientist Linnaeus divided all the living beings into two classes, namely all plants under the kingdom ‘Plantae’ and all the animals under ‘Animalia’.Three-kingdom classification : In 1866 Haeckel classified all living beings into three. Plants, Animals and third was Protista. Third was to give a place for primitive

Enzymes : Enzymes are proteins molecules which facilitate specific reactions towards equilibrium.These are commonly called organic catalysts.Substrates : The substrates are the molecules bound to and acted on by enzymes.Nature of enzymes : All enzymes are proteins, molecules. Most of them are composed of derivative proteins. The enzyme complex is called holoenzyme. It is composed

The cell is the basic unit of life.Cell : Cell is the basic unit of structure and function in living organisms.Cell Theory1. All living things are composed of cells.2. All cells arise from pre-existing cells.3. All cells in chemical composition and metabolic activities are alike.4. The function of an organism depends totally on the activities

Before the invention of microscope, the cell and its existence was not known to man. The study of cell biology has been inseparable from the evolution of the microscope. The 19th century was an era in which microscope contributed a lot to the extensive study of cell. The limit of resolution of an unaided human

Biology : Biology is the branch of science which deals with living things i.e. animals and plants.The word ‘Biology’ has been derived from two Greek words viz. bios meaning life and logos meaning study.There are three main studies in biology.(i) Botany : It deals with the study of plants.(ii) Zoology : It deals with the