Class 7 Science
Food is the most important and basic thing for life. Carbohydrates, proteins, fats, vitamins and minerals are the components of food. These components are necessary for all living beings. All plants and animals require food for their growth and getting energy. The process of utilization of food by an animal to obtain energy for growth and development is known as nutrition. Plants make their food themselves but animals cannot. Hence, animals depend directly or indirectly on the plant.
Question 1: What are the components of food?
Answer: Carbohydrates, proteins, fats, vitamins and minerals are the components of food.
Question 2: What is nutrition?
Answer: The process of utilization of food by a living organism to obtain energy is called nutrition.
Question 3: Why is need of nutrition?
Answer: Animals do not make their food themselves which plants do. Animals eat plants or plant eating animals. Hence, animals are directly or indirectly depend on plants.
Mode of nutrition in plant
Auto means self and trophos means nourishment. Plants are called autotrophs because they make their food themselves. The making of food for themselves is called the Autotrophic nutrition. Autotrophic nutrition is found in green plants, and in some bacteria.
The word Heterotrophic is the combination of two words i.e. Hetero + Trophos. Hetero means ‘others’ and ‘trophos’ means nourishment. If organisms depend on others for their food, such a mode of nutrition is called Hetetrophic Nutrition.
Animals cannot make their food themselves. They depend for food upon plants. Therefore, nutrition in animals is called Hetetrophic Nutrition. Animals are known as Heterotrophs.
The uptake of nutrients by organism from dead and decaying matter in the form of solution is called the saprotrophic nutrition. The organisms which use saprotrophic mode of nutrition are called saprotrophs. For example: fungi.
Questions 1: What is autotroph?
Answer: Organisms that make their food themselves are called autotrophs.
Question 2: What is autotrophic mode of nutrition?
Answer: The mode of nutrition in which the organism makes its own food is called autotrophic mode of nutrition.
Question 3: Give some example of autotrophs.
Answer: All green plants, such as grass, mango, bougainvillea, etc. are the examples of autotrophs. Some bacteria also show autotrophic nutrition.
Question 4: What is heterotrophic mode of nutrition?
Answer: The mode of nutrition in which an organism takes food from another organism is called heterotrophic mode of nutrition. The nutrition in animals and non-green plants is the example of heterotrophic mode of nutrition.
Question 5: Give examples of Heterotrophs.
Answer: Animals and non green plants are the examples of heterotrophs.
Question 6: What are saprotrophs?
Answer: Organisms which get their nutrition from dead or decaying plants in liquid form are called saprotrophs.