Nutrition in Animals is Chapter 2 taken from JKBOSE and NCERT textbook of Science for students of Class 7th. In the previous post, I provided you with Questions and Answers for Chapter 1 Nutrition in Animals. This post is about Nutrition in Animals Class 7th Question Answers. Before we move on to solutions you must have your basics clear. So, let me begin by giving you a brief overview of what you have studied in this chapter.
Nutrition in Animals Class 7th Question Answers
Overview of Chapter
- Different ways of taking food.
- Digestion in Humans.
- Digestion in Grass Eating Animals.
- Feeding and Digestion in Amoeba.
All animals including human beings require food for obtaining energy for the growth and repair of damaged body parts. Plants can make their food through the process of photosynthesis while animals obtain their food from plants and other animals. The process of taking in food by an animal and its utilisation in the body is called animal nutrition. Nutrition in animals takes place in five steps:
- Ingestion.
- Digestion.
- Absorption.
- Assimilation.
- Egestion.
Different ways of taking food
Different types of animals show different modes or methods of taking food into their body. Every animal has some special structures (or organs) for taking food inside its body. Various modes of taking food from different animals are given below:
Digestion in Humans
The human digestive system consists of the alimentary canal and the associated glands. The various parts of the human digestive system are Mouth (Buccal Cavity), Oesophagus (Food Pipe), Stomach, Small Intestine, Large Intestine, Rectum and Anus. The process of digestion takes place as follows:
Food is taken into the body through the mouth. The process of taking food into the body is called ingestion. We chew the food with our teeth and break it down mechanically into small pieces. The food is also mixed with saliva released from salivary glands in our mouth. The saliva breaks down the starch into sugars. The food is swallowed after it is chewed properly. It then passes into the food pipe or oesophagus. Food is pushed down by the movement of the wall of the food pipe.
The swallowed food reaches the stomach via a food pipe. 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. The digestive juices break down the proteins into simpler substances. The food is partially digested in the stomach and then passes into the small intestine.
The small intestine is a highly coiled structure which receives secretions from the liver and the pancreas. Besides, its wall also secretes juices. The liver secretes bile juice which plays an important role in the digestion of fats. The pancreatic juices act on carbohydrates and proteins and change them to simpler forms partly digested food now reaches the lower part of the small intestine where the intestinal juice completes the digestion of all components of the food.
The digested food is now absorbed into the blood via walls of blood vessels in villi in the small intestine and is carried to various parts of the body with help of blood. The food when reaches the target organ or part is used to build complex substances. It is called assimilation.
The undigested food is passed into the large intestine where water is absorbed from it and the remaining undigested waste passes into the rectum and remains there as semi-solid faeces. This faecal matter is removed from the body through the anus. This process is called egestion.
Digestion in Grass Eating Animals.
Herbivorous animals such as cows, buffaloes, etc eat grass. These animals quickly swallow the grass and store it in a part of the stomach called the rumen. The food is not chewed completely. Rumen possesses cellulose-digesting bacteria which break down the food by fermentation. This partially digested food or grass present in the rumen of cows is called cud.
This cud is brought back into the mouth of the cow from the rumen into small lumps and the animal chews it again. This process is called rumination and animals are called ruminants.
When this cud is thoroughly chewed in the mouth of the cow, it is swallowed again. This time the chewed cud does not go back to the rumen but enters into the other compartments of the cow’s stomach and then into the small intestine for complete digestion and absorption of food. The cellulose-digesting bacteria are not present in the body of human beings, therefore human beings and other carnivores cannot digest cellulose present in plant food items.
Feeding and Digestion in Amoeba.
When Amoeba senses their food, it pushes out pseudopodia around the food particle and engulfs it. The two pseudopodia join around the food particle and trap the food particle with a little water forming a vacuole around the food, thus the food gets trapped. Digestive juices present inside the vacuole act on the food and break it into simpler substances. This digested food is then absorbed and used for the growth, maintenance and multiplication of Amoeba. The undigested food residue is expelled outside by the vacuole.
Nutrition in Animals Class 7th Questions
Exercises
- Fill in the blanks:
a) The main steps of nutrition in humans are _______, _______, _______, _______ and _______.
b) The largest gland in the human body is the _______.
c) The stomach releases hydrochloric acid and _______ juice which act on the food.
d) The inner wall of the small intestine has many finger-like outgrowths called _______.
e) Amoeba digests their food in the _______.
Ans.
a) The main steps of nutrition in humans are ingestion, digestion, absorption, assimilation and egestion.
b) The largest gland in the human body is the liver.
c) The stomach releases hydrochloric acid and gastric juice which act on the food.
d) The inner wall of the small intestine has many finger-like outgrowths called villi.
e) Amoeba digests their food in the food vacuole.
- Mark “T” if the statement is true and “F” if it is false:
a) Digestion of starch starts in the stomach. (False)
b) The tongue helps in mixing food with saliva. (True)
c) The gall bladder temporarily stores bile. (True)
d) The ruminants bring back swallowed grass into their mouth and chew it for some time. (True)
- Tick mark (√) the correct answer in each of the following:
a) Fats are completely digested in the:
(i) Stomach
(ii)Mouth
(iii) Small intestine
(iv) Large intestine
Ans. Small Intestine
b) Water from the undigested food is absorbed mainly in the
(i) Stomach
(ii) Food pipe
(iii) Small intestine
(iv) Large intestine
Ans. Large Intestine
c) The process of taking food into the body is called:
(i) Digestion
(ii) Absorption
(iii) Ingestion
(iv) Assimilation
Ans. Ingestion
d) Which of the following is the largest gland in the human body
(i) Pancreas
(ii) Liver
(iii) Salivary gland
(iv) Thyroid
Ans. Liver
e) Finger-like projections called villi are present in
(i) Small intestine
(ii) Stomach
(iii) Rectum
(iv) Large intestine
Ans. Small intestine
f) Which of the following is a ruminant
(i) Amoeba
(ii) Man
(iii) Cow
(iv) Earthworm
Ans. Cow
- Match the items of Column I with those of Column II:
Ans.
5. What are villi? What are their location and function?
Ans. Villi are small finger-like projections or outgrowths present on the inner lining of the small intestine. They are present in the small intestine. The villi increase the surface area for the absorption of food. They have a network of blood vessels near the surface which help in the absorption of digested food.
6. Where is the bile produced? Which component of the food does it help to digest?
Ans. Bile is produced in the largest gland of the human body which is the liver and is temporarily stored in the gall bladder. It gets mixed with food in the small intestine and helps in the digestion of fats.
7. Name the type of carbohydrates that can be digested by ruminants but not by humans. Give the reason also.
Ans. Cellulose is a type of carbohydrate which can be digested by ruminants but not by humans because ruminants have a large sac-like structure called a rumen between the small intestine and large intestine. There are certain bacteria present in the rumen which are responsible for the digestion of cellulose.
8. Why do we get instant energy from glucose?
Ans. Glucose is a simple form of carbohydrate. It is easily absorbed by blood and hence provides instant energy to the body.
9. Which part of the digestive canal is involved in:
i) Absorption of food _________.
ii) Chewing of food _________.
iii) Killing of bacteria _________.
iv) Complete digestion of food _________.
v) Formation of faeces _________.
Ans.
i) Absorption of food small intestine.
ii) Chewing of food buccal cavity.
iii) Killing of bacteria stomach.
iv) Complete digestion of food small intestine.
v) Formation of faeces large intestine.
10. Write one similarity and one difference between the nutrition in amoeba and humans.
Ans. The similarity between nutrition in Amoeba and Humans.
Amoeba and humans both are heterotrophs. The digestion of food takes place in both organisms in which complex food is broken down into simpler forms.
Difference between nutrition in Amoeba and Humans.
The main difference in the nutrition of amoeba and humans is the complexity of their digestive systems. Human beings have well-developed complex digestive system while amoeba has only a food vacuole for the digestion of food.
- Match the items of Column I with suitable items from Column II:
Column I | Column II |
---|---|
(a) Salivary gland | i. Bile juice secretion |
(b) Stomach | ii. Storage of undigested food |
(c) Liver | iii. Saliva secretion |
(d) Rectum | iv. Acid release |
(e) Small intestine | v. Digestion is completed |
(f) Large intestine | vi. Absorption of water |
Ans.
Column I | Column II |
---|---|
(a) Salivary gland | iii. Saliva secretion |
(b) Stomach | iv. Acid release |
(c) Liver | i. Bile juice secretion |
(d) Rectum | ii. Storage of undigested food |
(e) Small intestine | v. Digestion is completed |
(f) Large intestine | vi. Absorption of water |
- Label Fig. 2.11 of the digestive system.
Ans.
- Can we survive only on raw, leafy vegetables/grass? Discuss?
Ans. No, we cannot survive only on raw, leafy vegetables/grasses because human beings do not have cellulose-digesting enzymes in our digestive system. Also, our bodies need carbohydrates and proteins to survive.
Leave a Reply