CBSE Class 7 Science Exemplar: Nutrition in Animals NCERT Solutions
This resource provides comprehensive NCERT Solutions for CBSE Class 7 Science Exemplar, Chapter 2: Nutrition in Animals. It covers essential concepts related to the digestive system, including the types of teeth and their functions, the role of the oesophagus, stomach acid, and the process of digestion. The solutions explain how different food components react with iodine, the functions of various organs in the alimentary canal, and the mechanism that moves food down the digestive tract. These detailed explanations and step-by-step answers are designed to help students grasp complex biological processes, clarify doubts, and prepare effectively for their examinations by reinforcing their understanding of nutrition in animals.
Quick info
| Board | CBSE |
|---|---|
| Class | Class 7 |
| Subject | Science Exemplar |
| Session | 2026 |
| Language | English |
| Type | NCERT Solutions |
| Chapter | Chapter 2 |
Chapter summary
Chapter 2 of the CBSE Class 7 Science Exemplar focuses on Nutrition in Animals. The NCERT Solutions provided here break down key concepts such as the identification of starch in food items using iodine, the different types of human teeth (incisors, canines, premolars, molars) and their specific roles in digestion, and the organs involved in the alimentary canal that do not perform digestive functions. It also explains the muscular action that propels food and the crucial role of stomach acid in eliminating harmful bacteria. These solutions offer a clear understanding of the digestive process in animals.
Learning outcomes
- Identify the presence of starch in food items using the iodine test.
- Differentiate between the structure and function of various human teeth.
- Recognize organs in the alimentary canal that are not involved in digestion.
- Explain the role of stomach acid in killing bacteria.
- Describe the muscular mechanism that moves food through the alimentary canal.
Topics covered
Paper topics
- Nutrition in Animals
- Digestion Process
- Types of Teeth
- Functions of Teeth
- Iodine Test for Starch
- Alimentary Canal Organs
- Oesophagus Function
- Stomach Acid
- Peristalsis
- Water Absorption in Large Intestine
- Faeces Formation
- Food Processing
Important topics
- Types of Teeth and their Functions
- Role of Stomach Acid
- Mechanism of Food Movement (Peristalsis)
- Iodine Test for Starch
- Organs Not Involved in Digestion
PDF preview
Read page by page below. PDF is streamed from the official NCERT website — no download button on this page.
Questions and Solutions
Multiple Choice Questions
1. Given below from (i) to (iv) are some food items:
(i) Boiled and mashed potato
(ii) Glucose solution
(iii) A slice of bread
(iv) Mustard oil
Which of the above food items will give a blue-black colour when tested with iodine?
(a) (i) and (ii)
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (iii) and (iv)
Explanation: Food items (i) Boiled and mashed potato and (iii) A slice of bread are rich in starch. When iodine solution is added to starch, it reacts to produce a characteristic blue-black color. Glucose solution (ii) is a simple sugar and does not contain starch, and mustard oil (iv) is a fat, neither of which will give a blue-black color with iodine.
2. Which of the following pairs of teeth differ in structure but are similar in function?
(a) Canines and incisors.
(b) Molars and premolars.
(c) Incisors and molars.
(d) Premolars and canines.
Explanation: Our teeth are specialized for different functions in chewing food. Incisors are the front teeth used for cutting. Canines are pointed teeth used for tearing food. Premolars and molars are located at the back of the mouth and are broader, designed for grinding and crushing food. While premolars and molars have distinct structures, their primary shared function is the efficient grinding of food before swallowing.
3. Read carefully the terms given below. Which of the following set is the correct combination of organs that do not carry out any digestive functions?
(a) Oesophagus, Large Intestine, Rectum
(b) Buccal cavity, Oesophagus, Rectum
(c) Buccal cavity, Oesophagus, Large Intestine
(d) Small Intestine, Large Intestine, Rectum
Explanation: The oesophagus is a tube that transports food from the mouth to the stomach; it does not digest food. The large intestine primarily absorbs water and electrolytes from the remaining indigestible food matter and transmits the useless waste material from the body. The rectum stores faeces before they are eliminated. Therefore, these organs do not perform digestive functions.
4. The swallowed food moves downwards in the alimentary canal because of:
(a) force provided by the muscular tongue.
(b) the flow of water taken with the food.
(c) gravitational pull.
(d) the contraction of muscles in the wall of food pipe.
Explanation: The movement of food down the alimentary canal is achieved through a process called peristalsis. This involves the rhythmic contraction and relaxation of the smooth muscles present in the walls of the oesophagus and other parts of the digestive tract, which propels the food forward.
5. The acid present in the stomach:
(a) kills the harmful bacteria that may enter along with the food.
(b) protects the stomach lining from harmful substances.
(c) digests starch into simpler sugars.
(d) makes the medium alkaline.
Explanation: The stomach secretes hydrochloric acid, which creates a highly acidic environment (pH 1.5-3.5). This acidity is crucial for killing ingested microorganisms, such as bacteria, that might be present in the food, thus preventing infections. While the acid also helps in activating pepsin for protein digestion, its primary role among the given options is to act as a barrier against harmful pathogens.
Common mistakes
- Confusing the functions of different types of teeth.
- Misidentifying organs that do not participate in digestion.
- Incorrectly explaining the action of stomach acid.
- Not understanding the peristaltic movement of the food pipe.
Revision tips
- Review the iodine test for starch and its results.
- Memorize the names and functions of all types of teeth.
- Understand the pathway of food and the role of each organ.
- Focus on the specific functions of stomach acid and peristalsis.
Practice MCQs
Q1. Which of the following food items will turn blue-black when tested with iodine solution?
Explanation: Boiled and mashed potato and a slice of bread contain starch, which reacts with iodine to produce a blue-black color. Glucose solution and mustard oil do not contain starch.
Q2. Which pair of teeth have different structures but similar functions in chewing food?
Explanation: Molars and premolars are both involved in grinding and crushing food, although they have slightly different structures. Incisors are for cutting, and canines are for tearing.
Q3. Which set of organs in the alimentary canal do not perform any digestive functions?
Explanation: The oesophagus transports food, the large intestine absorbs water, and the rectum stores faeces. None of these organs actively digest food.
Q4. The downward movement of food in the alimentary canal is primarily due to:
Explanation: The contraction and relaxation of muscles in the wall of the oesophagus and other parts of the alimentary canal, a process called peristalsis, propels food downwards.
Q5. What is the main function of the acid present in the stomach?
Explanation: Hydrochloric acid in the stomach creates an acidic environment that kills most of the harmful bacteria and other microorganisms that may be ingested with food.
Frequently asked questions
What is the purpose of the iodine test mentioned in the solutions?
The iodine test is used to detect the presence of starch in food items. A blue-black color indicates that starch is present.
How do molars and premolars differ from incisors and canines in terms of function?
Molars and premolars are primarily used for grinding and crushing food, while incisors are for cutting and canines are for tearing food.
Which organs in the digestive system do not actively digest food?
The oesophagus, large intestine, and rectum are mentioned as organs that do not carry out digestive functions; they are involved in transport, water absorption, and waste storage, respectively.
What causes food to move down the food pipe?
Food moves down the food pipe (oesophagus) due to the rhythmic contraction and relaxation of the muscles in its walls, a process known as peristalsis.
Why is the acid in the stomach important?
The acid in the stomach, primarily hydrochloric acid, is crucial for killing harmful bacteria that may enter with food and for creating an optimal environment for digestive enzymes.
Are these solutions aligned with the CBSE Class 7 Science curriculum?
Yes, these solutions are specifically designed for the CBSE Class 7 Science Exemplar, Chapter 2: Nutrition in Animals, providing accurate and relevant content for students.
Content reviewed by the NCERT Help team. Editorial Team and update policy
NCERT Solutions PDF PDF on NCERT Help. URL unchanged for search indexing.