Class 7 Science Chapter 2

Hiiii Important Main Point In Class 7 Science Chapter 2

1. Different Ways Of Taking Food

We have already studied about the nutrition in plants. This part of the content describes the nutritional needs and digestive system in human beings, along with other living beings. As we know that food is needed for every living organism. Plants can prepare their own food but animals cannot. But we know nutrition is required for every organism for energy. The food contains some nutrients like carbohydrate, protein, fat, vitamin and minerals which are required by our body for growth and development, called ‘Nutrition’. Generally, in the process of nutrition, food is taken as a complex substance and break down in simpler substances, called ‘Digestion’. After that, it is utilised by our body. You may have observed that different types of animals show different modes of nutrition. Such as, eagle tear flesh of prey, hummingbirds suck the nectar from the flower, mosquito and lice suck blood from other organisms. And amoeba capture and swallow tiny aquatic animals, snake-like python swallow others animal on the whole, human and many other animals feed on mother’s milk.

2. Digestion In Human

In this part of the content gives sufficient idea about the journey of food in human beings. As you learnt before in the process of digestion, food is breakdown in simple substances and after it is utilised by our body. The journey of our food starts from the buccal cavity (mouth) then it moves on food pipe or oesophagus and after it reaches to the stomach, small intestine and next to the large intestine and last the anus. Remember, tooth and digestive glands play an important role in our digestion.

3. Process Of Digestion

As you know, food is taken through the mouth with the help of teeth food is breakdown. You must know that our mouth has salivary glands. It secrets a juice, called saliva. We use our tongue for talking beside it mixes saliva with the food and helps in swallowing food. The swallowed food passes into the food pipe and reaches into the stomach. You know digestive juices and acids are present in the stomach which helps the food to digest due to some of the physical and chemical changes. Partially digested food reaches the small intestine where intestinal juices complete the digestion. You are surprised to know that our small intestine is 7.5 metres long and highly coiled. Similarly, our large intestine is about 1.5 metre-long, and it helps to remove waste material time-to-time through the anus.

4. Digestion In Grass Eating Animals

You may have observed that cows, buffaloes and other grass-eating animals chewing continuously, even when they are not eating. They quickly swallow the grass and store it in a part of a stomach, called ‘Rumen’. Hence, they are called ruminants. You may know that partially digested food or grass present in the rumen of a cow is called ‘Cud’. When this cud is thoroughly chewed in the mouth of the cow and swallowed again and reaches small intestine for complete digestion and absorption of food.

5. Feeding And Digestion In Amoeba

Have you ever seen amoeba? Your answer will be ‘no’. Do you know amoeba cannot see by naked eyes? Amoeba is single-celled microscopic organisms which are found in pond, lakes and other water sources. The body of amoeba has a finger-like projection called pseudopodia or false feet. It captures food and helps in locomotion of amoeba. Then the captured food break-down into simpler substances for digestion. This digested food is then absorbed and used for growth and maintenance by amoeba. In this way, you can see animals obtain their nutrients through a wide variety of feeding patterns. As nutrition is a must for a variety of reasons. Animals need the proper nutrition for growth, maintenance, transportation of materials and to provide energy for work and vital functions for their survival or existence.

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