7th Class

     Nutrition in Animals   Nutrition in animals is quite different from the nutrition in plants. The animals are heterotrophs because they cannot prepare their own food. They depend on plants and other animals for their nutritional requirement. Animals in fact, gather food from different sources. Big animals require huge amount of food for their nutritional needs.   Look at the flow chart of nutrition in animals  

     Digestion in Animals   Digestion of food in animals include mainly four stages, that is, ingestion, digestion, absorption and excretion. The process of taking food inside the body is called ingestion. The process, by which the food is broken down into small pieces by the digestive juice, is called digestion. The digested food is absorbed by the intestine, which is called absorption. Undigested food and waste materials from the body are released in the form of stool and urine. This process is called as excretion.    Look at the following picture of digestive system of herbivorous and carnivorous Animal:                                     Digestive system of a cow                                                           Digestive system of a lion              Digestive system of a more...

       Digestive system of Human   Human digestive system is consisted of many parts. Each of the parts has a distinct function to perform.   Look at the following picture of human digestive system                Oral or Buccal Cavity Our mouth is the first organ of the digestive system, which is known as oral or buccal cavity. When we eat food, the teeth part of our mouth breaks food into small pieces. Oral cavity contains a muscular organ called tongue. It helps in mixing the food with saliva secreted by salivary gland. Thus digestion of food begins in the mouth.              Esophagus Esophagus is a tube like structure, which brings food from mouth to more...

     Chemical Reactions   The chemical reaction is the process in which two substances combine and form a new substance. Chemical reactions are widely used for the formation of desired substances. The substances, which are initially involved in the chemical reaction are called reactants. And the substance, which we get after completion of chemical reaction, is known as products.   Look at the following chemical reaction of Hydrogen and Oxygen     In the above picture, molecules of hydrogen and oxygen combine together to form molecules of water.                Types of Reactions Types of reaction depend on nature of the combination of reactants and energy released or absorbed by the resulting chemical, after the reaction. There are three types of reaction, more...

      Chemical Bonding   Atoms of the elements lose and gain electrons to form new substances. The process, by which they form the new substances, is called chemical bonding. An atom of a substance is made up of three fundamental particles, i.e. electrons, protons and neutrons. Out of three particles, protons and electrons are charged whereas neutron does not possess any charge. Protons are positively charged and electrons are negatively charged. Two like charges repel each other and two unlike charges attract each other. Negatively charged electrons orbiting the nucleus, whereas protons are present in the nucleus. The atoms, which lose electrons in a chemical bonding is called positive ions or cations. The atoms, which gain electrons are called negative ions or anions. For example, reaction between sodium (Na) and chlorine  leads to the transfer of electrons from Na more...

     Dissolution of Solid   In a dissolution process, two substances are required. One is called solvent and the other is solute. The substance, which dissolves in another substance, is called solute and the substance in which the solute dissolves, is called solvent. In this process the quantity of the solvent is greater than the solute. The dissolution of salt in water is dissolution of solid in liquid. The dissolution of salt in water is due to the attraction of positive and negative charges. Water is the chemical compound of hydrogen and oxygen. Two molecules of hydrogen and one molecule of oxygen forms a molecule of water.   Look at the following picture of dissolution of salt in water   The dissolution of sugar in water is also dissolution of solid in liquid. The solid can more...

     Chemical Equations   Chemical equation is the symbolic representation of a chemical reaction. The reactants of the reaction are represented on the left hand side of the equation and products are represented on right hand side. The representation of reactants in an equation are in symbolic form. Plus sign between the reactants separates every reactant. On the right hand side, every product is also separated by plus sign. The arrow mark (read as yield) between the reactants and resulting elements is used to denote the net forward reaction. Following symbol is used between the reactants and products. = Symbol is used to denote a stoichiometric relation.  Symbol is used to denote the chemical reaction in both directions or reversible reaction.  Symbol is used to denote equilibrium. The physical state of the chemicals are more...

         Surrounding Affects the Living Things   Our earth is the third planet and only one capable of supporting life in the solar system. The distance between the Sun and the Earth is about, 14, 95, 65, 1,39 km. It varies slightly during the year. The variation of distance between the Earth and Sun is due to the angle of the earth axis, relative to the Sun. There are various kinds of species living on the Earth. All living organisms require food to survive and they obtain food from plants and animals. Therefore, all living organism, directly or indirectly depend on plants. The natural resources such as plants, animals, minerals, water and air are of two types, renewable resources and nonrenewable resources. Renewable resources are replaced by natural process. The water cycle is an example of renewable resource. Oxygen is obtained from more...

     Introduction   Plants require water, sunlight, carbon dioxide and minerals for making their food. These nutrients in the plants are converted into glucose by the process of photosynthesis. The growth rate of a plant mainly depends on the availability of nutrients in the soil on which the plant grows. Lack of nutrients in the soil cause improper growth and shorter life-span of the plant. There are two modes of nutrition’s in plants. These are autotrophs and heterotrophs. Heterotrophic plants are further classified into three groups, saprophytes, parasite and insectivores. The living organisms, which make their own food by photo syntheses with the help of chlorophyll present in their body, have autotrophs mode of nutrition. The living organisms, which are unable to make their own food and depend on the autotrophs for their nutritional needs, is said to have heterotrophs mode of nutrition. In more...

         Nutrition in a Non Green Plants (without chlorophyll)   We have studied about the involvement of chlorophyll in the process of photosynthesis. Whole process of photosynthesis depends on the presence of chlorophyll in the plant. The process of photosynthesis in general condition is not possible without chlorophyll. However, there are many plants in our surrounding which do not have chlorophyll such as, cuscuta, monotropa, etc. They all depend on heterotrophic mode of nutrition such as, saprophytic, parasitic and insectivorous.              Saprophytes Saprophytic plants live and grow on dead and decaying organic matters. It secretes enzyme to break down the complex organic compound into its simpler form for the absorption.   Look at the following picture of non-green (saprophytic) plants:         more...