1 RAJESH NAYAK IMPORTANT CHAPTERS FROM NCERT SCIENCE CONTENTS CLASS PHYSICS CHAPTER CHEMISTRY CHAPTER BIOLOGY CHAPTER 7 TH 4, 13, 14 & 15 5 & 6 1, 2, 10, 11 & 12 8 TH 11, 12, 13, 14, 15 & 16 3, 4, 5 & 6 2, 8, 9 & 10
2 RAJESH NAYAK SCIENCE-CLASS-VII CHAPTER-1-NUTRITION IN PLANTS Carbohydrates, proteins, fats, vitamins and minerals are components of food. These components of food are necessary for our body and are called nutrients. Nutrition is the mode of taking food by an organism and its utilisation by the body. The mode of nutrition in which organisms make food themselves from simple substances is called autotrophic (auto = self; trophos = nourishment) nutrition. plants are called autotrophs. Animals and most other organisms take in readymade food prepared by the plants. They are called heterotrophs (heteros =other). the bodies of living organisms are made of tiny units called cells. Cells can be seen only under the microscope. Some organisms are made of only one cell. The cell is enclosed by a thin outer boundary, called the cell membrane cell membrane. Most cells have a distinct, centrally located spherical structure called the nucleus. The nucleus is surrounded by a jelly-like substance called cytoplasm. Carbon dioxide from air is taken in through the tiny pores present on the surface of the leaves. These pores are surrounded by ‘guard cells’. Such pores are called stomata. The leaves have a green pigment called chlorophyll. It helps leaves to capture the energy of the sunlight. This energy is used to synthesise (prepare) food from carbon dioxide and water. Since the synthesis of food occurs in the presence of sunlight, it is called photosynthesis (Photo: light; synthesis : to combine). So we find that chlorophyll, sunlight, carbon dioxide and water are necessary to carry out the process of photosynthesis. During photosynthesis, chlorophyll containing cells of leaves in the presence of sunlight, use carbon dioxide and water to synthesize carbohydrates. During the process oxygen is released. The carbohydrates ultimately get converted into starch. The presence of starch in leaves indicates the occurrence of photosynthesis. The starch is also a carbohydrate. You often see slimy, green patches in ponds or in other stagnant water bodies. These are generally formed by the growth of organisms called algae. They contain chlorophyll which gives them the green colour. Algae can also prepare their own food by photosynthesis. The carbohydrates are made of carbon, hydrogen and oxygen. These are used to synthesise other components of food. proteins are nitrogenous substances which contain nitrogen. Soil has certain bacteria that convert gaseous nitrogen into a usable form and release it into the soil.