NCERT Solutions For Class 7 Science Chapter 2: Nutrition in Animals

Are you looking for NCERT Solutions for Class 7 Science Chapter 2? Extramarks offers detailed solutions to questions given at the end of this chapter for students’ reference. Students can access these solutions for free from the links provided below. The solutions provided here have been prepared by subject experts that have given special attention to providing accurate solutions in a step-by-step manner. Students can use these for their exam preparations, last-minute revisions, and for help with their assignments.

NCERT Solutions for Class 7 Science Chapter 2

Access NCERT Solutions for Class 7 Science Chapter 2 – Nutrition in Animals

Class 7 Science Chapter 2 Nutrition in Animals 

Students can access the NCERT Solutions for Class 7 Science Chapter 2 Nutrition in Animals for their future reference. To get the best of these resources, students should first read the chapter thoroughly and then try to attempt all the questions on their own. They can always use NCERT Solutions for their reference if they even get stuck on a question. These resources will also help students understand how to frame their answers during their exams.

Chapter 2 – Nutrition in Animals

Chapter 2 of Class 7 Science NCERT textbook teaches students about how different Animals get the nutrients that their bodies require for proper functioning and growth. Students learn about human & animal nutrition, digestion, simple organisms, the nutritional process, the digestive system, and the different stages involved in the digestive process.

2.1 Different Ways of Taking food

Unlike plants, animals cannot synthesise their own food. Rather, they depend on plants and other animals for the nutrients that their bodies require for proper functioning and growth. Food is consumed in various ways by various species. Bees and hummingbirds prefer to sip plant nectar. Human and other animal infants swallow their mothers' milk. Snakes pursue their prey and eat it entirely. Some aquatic creatures feed on food particles that float freely in the water.

2.2 Digestion in Humans

Food is ingested by humans through their mouths. After that, food particles get digested and utilised for various biological functions. Defecation occurs to get rid of unwanted and undigested food.

A continuous canal extends from the buccal cavity to the anus, allowing food to reach the stomach. This canal is divided into many portions, as follows:

  • The oral cavity 
  • The oesophagus, sometimes known as the food pipe
  • Stomach
  • The small intestine 
  • The large intestine terminates in the rectum.
  • Aneurysm

The digestive system, also known as the alimentary canal, comprises various components. Food is gradually digested and reaches our system as it passes through the canal's numerous compartments. The digestive process gets carried out by digestive fluids secreted in the inner walls of the stomach, small intestine, and other digestive glands such as the salivary glands, pancreas, and liver. Digestive fluid aids digestion by breaking down meal particles into smaller pieces.

The Mouth and Buccal Cavity

We take whatever food we ingest into our bodies through our mouths. Ingestion is the term for the process of bringing food into the body. Our teeth assist us in chewing and breaking down the ingested food into smaller pieces. Each tooth root has its socket, which gets inserted into the gums. We can divide Teeth according to their functions and appearance. These are the features:

  • Biting and cutting
  • Tearing and piercing
  • Grinding and chewing

Milk Teeth and Permanent Teeth

Milk teeth are the first set of teeth that appear in infants. They emerge in a child's mouth and fade out between the ages of six and eight. Each tooth is extracted from the root and replaced with a permanent tooth. These teeth may last a lifetime or fall out when a person reaches a certain age. Permanent teeth might fall out as a result of dental disorders.

Sweets and Tooth Decay

Bacteria are found in our mouths daily, although they are not always dangerous. These microorganisms may cause difficulties if we do not take care of our teeth and gums. They grow in an area between your teeth's gaps and fractures. As a result, brushing and flossing your teeth after each meal is essential. Bacteria cause damage to our teeth by generating acids, which are subsequently utilised to break down sugar from remaining food particles in the mouth. It is known as tooth decay. Untreated dental decay can cause severe toothaches and possibly tooth loss. Sugary meals like chocolates, candies, soft drinks, and other sugary beverages induce tooth damage. As a result, cleaning your teeth and using a tongue scraper to remove germs from the pores of your tongue is crucial.

The Food Pipe/Oesophagus

Food goes via a food pipe or oesophagus after we consume it. From the neck to the ends of the chest, the food pipe runs. In a nutshell, it connects our stomach to where our mouth ends. Food is forced down to the stomach through the food pipe due to movement in the wall. This motion is regular across the alimentary canal since the system continuously pushes the food lower. Our stomach may refuse to accept ingested food particles in some settings and types of food, resulting in vomiting.

The Stomach

In the alimentary canal, the stomach is a large section. It's a bag with a thick wall that resembles a flattened U. This section of the canal is the widest. Food enters our stomach through one end (the food pipe) and exits through the other side. The food particles pass through the aperture and into the small intestine. The stomach's inner lining secretes mucus, hydrochloric acid, and digestive fluids to extract the meal's nutrients. They are protein, glucose, minerals, water, and other substances. The mucous coating of the stomach protects it from bacteria, and the acid generated kills bacteria that enter with the meal.

Small Intestine

The small intestine is about 7.5 metres  in length. It is a tightly coiled tube. The gut's inner wall secretes liquid, which helps digest the remaining food. The liver produces bile. It gets then stored in the gallbladder, a significant sac. Bile is a crucial component of digestion, especially when it comes to lipids. The partially digested food gets subsequently transported to the lower intestine, where it completes the last stage of digestion.

Large Intestine

The large instance is slightly broad and short compared to the small intestine. It is around 1.5 metres long. It is in charge of absorbing water and salts from uneaten food particles. The rectum receives the undigested food in the form of waste. They're kept in the same way as semi-solid faeces are. The anus is then used to eliminate faecal waste from the body. The process is known as egestion.

Diarrhoea

Diarrhoea can happen when our digestive system fails. So you might get an infection, indigestion, or food poisoning. It is a somewhat regular occurrence among children, and in severe cases, it can be fatal. Excess salt and water loss from the body may be detrimental to our health.

Key Features of NCERT Solutions for Class 7 Science Chapter 1

The following are some key features that distinguish Extramarks from other online study platforms:

  • The language in the online material is simple and easy for Class 7 students to understand.
  • The solutions include thorough explanations along with examples and illustrations wherever required and are prepared by subject matter experts that have years of experience in their respective fields.

Q.1 Fill in the blanks:

(a) The main steps of nutrition in humans are __________, __________, __________, _________ and __________.
(b) The largest gland in the human body is __________.
(c) The stomach releases hydrochloric acid and ___________ juices which act on food.
(d) The inner wall of the small intestine has many finger-like outgrowths called _________.
(e) Amoeba digests its food in the ____________.

Ans-

(a) ingestion, digestion, absorption, assimilation, egestion
(b) liver
(c) digestive
(d) villi
(e) food vacuole

Q.2 Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) Digestion of starch starts in the stomach. (T/F)
(b) The tongue helps in mixing food with saliva. (T/F)
(c) The gall bladder temporarily stores bile. (T/F)
(d) The ruminants bring back swallowed grass into their mouth and chew it for some time. (T/F)

Ans-

(a) False
(b) True
(c) True
(d) True

Q.3 Tick (√) mark the correct answer in each of the following:

(a) Fat is completely digested in the
(i) stomach
(ii) mouth
(iii) small intestine
(iv) large intestine

(b) Water from the undigested food is absorbed mainly in the
(i) stomach
(ii) food pipe
(iii) small intestine
(iv) large intestine

Ans-

(a) Fat is completely digested in the: (iii) small intestine
(b) Water from the undigested food is absorbed mainly in the: (iv) large intestine

Q.4 Match the items of Column I with those given in Column II:

Column I
Food components
Column II
Product(s) of digestion
Carbohydrates Fatty acids and glycerol
Proteins Sugar
Fats Amino acids

Ans-

Column I
Food components
Column II
Product(s) of digestion
Carbohydrates Sugar
Proteins Amino acids
Fats Fatty acids and glycerol

Q.5 What are villi? What is their location and function?

Ans-

Thousands of minute finger-like projections or outgrowths found in the inner wall of small intestine are called villi. These increase the surface area for maximum and quick absorption of digested food from small intestine into the blood stream.

Q.6 Where is the bile produced? Which component of the food does it help to digest?

Ans-

Bile is produced in the liver. It acts upon the fat component of food and breaks down large-sized fat droplets into smaller ones.

Q.7 Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also.

Ans-

Cellulose is the type of carbohydrate that can be digested by ruminants and not by humans. It is so because a large sac-like structure called rumen is found in the ruminants between food pipe and small intestine; that contains numerous bacteria which can digest cellulose. Human alimentary canal does not contain such cellulose digesting bacteria and thus, cannot digest cellulose.

Q.8 Why do we get instant energy from glucose?

Ans-

We get instant energy from glucose because it is the simplest sugar that readily breaks down into water and carbon dioxide with the release of energy in a living cell. All the food components ultimately get converted into glucose.

Q.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) Small intestine
(ii) Buccal cavity
(iii) Stomach
(iv) Small intestine
(v) Large intestine

Q.10 Write one similarity and one difference between the nutrition in amoeba and human beings.

Ans-

1. Nutrition in Amoeba is similar to that of human beings because both comprise of five basic steps, which are ingestion, digestion, absorption, assimilation and egestion.

2. One of the important differences in the nutrition in Amoeba with that of human beings is the lack of alimentary canal and digestive organs. Amoeba being a single-celled organism contains organelles for performing different set of functions instead of organs and organ systems.

Q.11 Match the items of Column I with suitable items in 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
(vii) Release of faeces

Ans-

Column I Column II
(a) Salivary gland (iii) Saliva secretion
(b) Stomach (iv) Acid release
(c) Liver (i) Bile juice secretion
(d) Rectum (vii) Release of faeces
(e) Small intestine (v) Digestion is completed
(f) Large intestine (vi) Absorption of water

Q.12 Label Fig. 2.11 of the digestive system.

The well labeled diagram of the given figure is as follows:

Q.13 Can we survive only on raw, leafy vegetables / grass? Discuss.

Ans- No, we cannot survive only on raw, leafy vegetables and grass. It is so because main component present in such a diet is cellulose which cannot be digested by human beings. Cellulose can only be digested by certain bacteria which are present in the rumen of ruminant animals. These bacteria breakdown the cellulose and produce nutrients and energy for themselves and the ruminants. Therefore, only ruminants can survive on diet consisting of raw vegetables and grass.

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FAQs (Frequently Asked Questions)
1. Explain the location and function of villi in Chapter 2 of NCERT Solutions for Class 7 Science.

Villi are finger-like extensions or outgrowths of our digestive system’s small intestine. Villi increase the amount of surface area accessible for food absorption and digestion.

2. Where does bile come from? What part of the food does it aid in the digestion of?

The liver produces bile. It aids in the breakdown of fats.