Class 7 Science Chapter 2 Important Questions

Class 7 Science Chapter 2 Important Questions with answers of Nutrition in Animals updated for new academic session 2020-21. Class 7 Science Chapter 2 Extra Questions cover all the keywords, notes based on NCERT Books and all important questions given as intext questions.

If a student go through all these questions, it means he has covered Chapter 2 of Class 7 Science with all keywords and all important topics. It contains many extra questions other than NCERT Solutions.

Class 7 Science Chapter 2 Important Questions 2020-21

Class:7
Subject:Science
Contents:Important Questions & Explanations

Class 7 Science Chapter 2 Extra Questions 2020-21

Class 7 Science Chapter 2 Important Questions are given below for academic session 2020-21. These questions cover all the keywords, explanations of chapter 2 of class 7 science and frequently asked questions in school exams or class tests. This section provides a complete revision of Class 7 Science Chapter 2. More questions will be added as per suggestions revived.

7th Science Chapter 2 Important Questions Set – 1

What do you mean by animal nutrition?

Animals get their food from plants, either directly by eating plants or indirectly by eating animals that eat plants. Animal nutrition includes nutrient requirement, mode of intake of food and its utilisation in the body.

Write different modes of taking food in any five animals.

The mode of taking food into the body varies in different organisms. Bees and humming-birds suck the nectar of plants, infants of human and many other animals feed on mother’s milk. Snakes like the python swallow the animals they prey upon. Some aquatic animals filter tiny food particles floating nearby and feed upon them.

“The food passes through various compartments in the human body”- name them.

The food passes through a continuous canal which begins at the buccal cavity and ends at the anus. The canal can be divided into various compartments: (1) the buccal cavity, (2) food-pipe or oesophagus, (3) stomach, (4) small intestine, (5) large intestine ending in the rectum and (6) the anus.

What do you mean by digestive system in human body?

The human digestive system consists of the alimentary canal and secretory glands. It consists of the (i) buccal cavity, (ii) oesophagus, (iii) stomach, (iv) small intestine, (v) large intestine ending in rectum and (vi) anus. The main digestive glands which secrete digestive juices are (i) the salivary glands, (ii) the liver and (iii) the pancreas.
The inner walls of the stomach and the small intestine, and the various glands associated with the canal such as salivary glands, the liver and the pancreas secrete digestive juices. The digestive juices convert complex substances of food into simpler ones. The digestive tract and the associated glands together constitute the digestive system.

Ingestion

Food is taken into the body through the mouth. The process of taking food into the body is called ingestion.

7th Science Chapter 2 Important Questions Set – 2

Define the term Milk TEETH and PERMANENT TEETH.

The first set of teeth grows during infancy and they fall off at the age between six to eight years. These are termed milk teeth. The second set that replaces them are the permanent teeth.

Write the different types of teeth found in human beings.

Incisors (number 8) for cutting and biting. Canines (number 4) for piercing and tearing. Premolars (number 8) and molars (number 12) for chewing and grinding.

What is the role of tongue in human body?

The tongue is a fleshy muscular organ attached at the back to the floor of the buccal cavity. It is free at the front and can be moved in all directions. We use our tongue for talking. Besides, it mixes saliva with the food during chewing and helps in swallowing food. We also taste food with our tongue. It has taste buds that detect different tastes of food.

What do you mean by the tooth decay?

Normally bacteria are present in our mouth but they are not harmful to us. However, if we do not clean our teeth and mouth after eating, many harmful bacteria also begin to live and grow in it. These bacteria break down the sugars present from the leftover food and release acids. The acids gradually damage the teeth. This is called tooth decay. If it is not treated in time, it causes severe toothache and in extreme cases results in tooth loss.

Digestion

The components of food such as carbohydrates are complex substances. These complex substances cannot be utilised as such. So, they are broken down into simpler substances. The breakdown of complex components of food into simpler substances is called digestion.

7th Science Chapter 2 Important Questions Set – 3
How does the food pipe or oesophagus help to taking food for digestive system in human beings?

The swallowed food passes into the food-pipe or oesophagus. The food-pipe runs along the neck and the chest. Food is pushed down by movement of the wall of the food-pipe. Actually, this movement takes place throughout the alimentary canal and pushes the food downwards.

What is ‘villus’ in human body? Write the role of the villus in digestive system.

The inner walls of the small intestine have thousands of finger-like outgrowths. These are called villi (singular villus).
The villi increase the surface area for absorption of the digested food. Each villus has a network of thin and small blood vessels close to its surface. The surface of the villi absorbs the digested food materials. The absorbed substances are transported via the blood vessels to different organs of the body where they are used to build complex substances such as the proteins required by the body.

Write down the role of stomach in digestive system.

The stomach is a U-shaped, thick-walled bag. The inner lining of the stomach secretes mucous, hydrochloric acid and digestive juices. The mucous protects the lining of the stomach. The acid kills many bacteria that enter along with the food and makes the medium in the stomach acidic and helps the digestive juices to act. The digestive juices break down the proteins into simpler substances.

What is egestion?

The faecal matter is removed through the anus from time-to-time. This is called egestion.

Absorption and Assimilation

After the stomach, the partly digested food reaches the lower part of the small intestine where the intestinal juice completes the digestion of all components of the food. The digested food can now pass into the blood vessels in the wall of the intestine. This process is called absorption.
The inner walls of the small intestine have thousands of finger-like outgrowths. These are called villi (singular villus). The surface of the villi absorbs the digested food materials. The absorbed substances are transported via the blood vessels to different organs of the body where they are used to build complex substances such as the proteins required by the body. This is called assimilation.

7th Science Chapter 2 Important Questions Set – 4
What do you mean by the term RUMEN, RUMINATION and RUMINANTS’?

Grass-eating animals (cows, buffaloes etc.) chewing continuously even when they are not eating. Actually, they quickly swallow the grass and store it in a part of the stomach called rumen.
Here the food gets partially digested and is called cud. But later the cud returns to the mouth in small lumps and the animal chews it. This process is called rumination. So, these animals are called ruminants.

Why do we not able to digest cellulose like cattle?

The cellulose of the food is digested by the action of certain bacteria which are not present in humans.

What is an ‘amoeba’?

Amoeba is a microscopic single-celled organism found in pond water. Amoeba has a cell membrane, a rounded, dense nucleus and many small bubble-like vacuoles in its cytoplasm.

What do you mean by Pseudopodia?

Amoeba constantly changes its shape and position. It pushes out one, or more finger-like projections, called pseudopodia or false feet for movement and capture of food.

Nutrition in Amoeba

Amoeba feeds on some microscopic organisms. When it senses food, it pushes out pseudopodia (which is false feet) around the food particle and engulfs it. The food becomes trapped in a food vacuole.
Digestive juices are secreted into the food vacuole. They act on the food and break it down into simpler substances. Gradually the digested food is absorbed.

7th Science Chapter 2 Important Questions Set – 5
What is the use of acid in stomach?

The inner lining of stomach secretes mucus, hydrochloric acid and digestive juices. Out of these HCL kills any bacteria that may enter the stomach with food and makes the medium acidic.
Mucus protects the stomach lining from HCL and digestive juices break down proteins in food into simpler substances.

Can we survive only on raw, leafy vegetables or gram? Discuss.

Raw leafy vegetables and grass are rich in cellulose, a type of carbohydrate. Many animals, including humans, cannot digest cellulose, because they do not have enzymes and certain types of bacteria which can digest cellulose. We cannot survive by taking vegetables in raw form. That’s why we boil or cook vegetables which breaks down cellulose into simple carbohydrates. We can only survive by taking in vegetables in boiled or cooked form.

Ruminants such as cow and buffaloes swallow their food hurriedly and then sit restfully and chew their food. Can you give reason, why?

Ruminants such as cows and buffaloes swallow their food hurriedly and store it in a part of the stomach called rumen. The cellulose of the food is digested here by the action of certain bacteria which are not present in humans.
Later, this partially digested food (cud) is returned to the buccal cavity of the animals in small lumps and animal it sitting restfully to complete the process of digestion. This process is called rumination.
The thoroughly chewed cud is swallowed again to other compartment of stomach and then into small intestine for complete digestion and absorption.

What is the function of enzymes present in the saliva?

The salivary gland present in mouth secretes saliva. It contains the enzyme amylase (ptyalin) that breaks down into simple sugars. Only about 30% starch digestion takes place in the mouth.

Nutrition in Amoeba and Human beings

Similarity: The basic process of digestion of food and release of energy is the same in amoeba as well as in human beings. In amoeba, digestive juices are secreted into the food vacuole. They act on the food and break it down into simpler substances. Gradually, the digested food is absorbed. Similarly, in human beings various digestive juices (mouth, stomach, intestine etc.) act on food and break it down to simpler substances.
Differences: The digestion process in amoeba is simple while in human beings it is a complex process. The process of ingestion and egestion are also quite different. Amoeba engulf its food by surrounding the food particles with its pseudopodia. The undigested food which is largely carbon dioxide gas is expelled out by the vacuole. Which is human beings, the food (which is complex substances) is taken inside the mouth and undergoes a complex process of digestion and absorption. Finally, the undigested food is expelled out in the form of faeces.

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