Ans: Food is a basic necessity for all living organisms to survive. It is because food provides energy to all living organisms to do their life activities. Food also helps them to grow and build their bodies
Q. What is nutrition?
Ans: The mode of taking food by an organism and utilizing it by the body is called nutrition.
Q. What are the modes of nutrition?
Ans: There are two modes of nutrition in organisms. They are autotrophic and heterotrophic nutrition
The mode of nutrition in which organisms make their own food is called Autotrophic Nutrition and eg. Green plants.
The mode of nutrition in which organisms depend on others for their food, is called Heterotrophic nutrition. E.g. All animals, including human beings.
Q. Why the sun is called the ultimate source of energy for all forms of life?
Ans: In the absence of the sun, there would be no photosynthesis. Hence, there would not be any food. In the absence of food, life would be impossible on earth. So, the sun is the ultimate source of energy for all forms of life.
For full Study visit:
CBSE NCERT Class 7 Science Nutrition in Plants