Study Material and Notes of Ch 1 Nutrition in Plants Class 7th Science
Topics in the chapter
• Introduction
• Mode of nutrition in Plants
• Photosynthesis
• Heterotrophic Nutrition
→ Types of Heterotrophic Nutrition
• Digestion in Human Beings
Introduction
→ Carbohydrates, proteins, fats, vitamins and minerals are components of food which 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.
Mode of Nutrition in Plants
→ Plants prepare their own food by using raw materials like water, carbon dioxide and minerals.
→ The mode of nutrition in which organisms make food themselves from simple substances is called autotrophic nutrition.
→ Plants are autotrophs as they make their own food.
→ The autotrophs manufacture their own food, they are called producers.
Photosynthesis
→ Synthesis of food by plants using carbon dioxide and water in the presence of sunlight with the help of chlorophyll is called Photosynthesis.
→ Leaves are the food factories of plants and sites for the synthesis of food.
→ The green pigment called chlorophyll is present in leaves.
→ Chlorophyll traps solar energy, which is used to prepare food from CO2 and water. Sun is the ultimate source of energy.
→ Green plants absorb CO2 from atmosphere through tiny pores called stomata.
→ Stomata are present on the surface of leaves.
→ Water and minerals are absorbed from soil and are transported to leaves via tiny vessel-like
structures present in roots.
→ Chlorophyll, sunlight, CO2 and water are essential raw materials for photosynthesis.
→ Carbohydrates such as starch and oxygen are the product of photosynthesis.
→ Autotroph form the first link in the food chain and all organisms on the earth obtain the energy directly or indirectly from them.
Heterotrophic Nutrition
→ In this type nutrition, organisms derive energy from plants and animal sources.
• Herbivores: The heterotrophs that derive their energy directly from plants are called herbivores.
• Carnivores: Those who derive their energy indirectly by eating herbivores are called carnivores.
• Omnivores: They feed on both plants and animals. Example: bear, rat, man etc.
• Decomposers: They obtain nutrients by breaking down remains of dead plants and animals, includes some bacteria and fungi.
Types of Heterotrophic Nutrition
(i) Holozoic
(ii) Parasitic
(iii) Saprophytic
Digestion in Human Beings
• Digestion: Mechanical and chemical reduction of ingested nutrients.
→ Human digestive system consists of long alimentary canal.
→ Alimentary canal includes- mouth, pharynx, oesophagus, stomach, small intestine, and large intestine
NCERT Solutions of Nutrition in Plants