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

1. Fill in the blanks:

a). The main steps of digestion in humans are _______, _______, _______, _______ and _______.

Ans: ingestion, digestion, absorption, assimilation and egestion.

b). The largest gland in the human body is _______.

Ans: Liver.

c). The stomach releases hydrochloric acid and _______ juice which acts on food.

Ans: Gastric.

d). The Inner wall of the small intestine has many finger-like outgrowths called_______.

Ans: Villi.

e). Amoeba digests its food in the _______.

Ans: Food vacuole.

2. Mark ‘T’ if the Statement Is True and “F” if It Is False.

a). Digestion of starch starts in the stomach.

Ans: F

Digestion of starch starts from the mouth.

b). The tongue helps in mixing food with saliva.

Ans: T

c). The gallbladder temporarily stores bile.

Ans: T

d). The ruminants bring back swallowed grass into their mouth and chew it for some time.

Ans: T

3. Tick () Mark the Correct Answers in Each of the Following:

a). Fat is completely digested in the 

1. Stomach 

2. mouth

3. Small intestine

4. large intestine.

Ans: (iii) Small intestine.

Fats are completely digested in the small intestine because it gets bile from the liver through the gallbladder which is responsible for fat digestion.

b). Water from the undigested food is absorbed mainly in the

1. Stomach

2. mouth

3. Small intestine 

4. large intestine.

Ans: (iv) Large intestine.

As it takes several hours for the food to travel to enter the large intestine through the digestive tract, the water from the undigested food should be cleaned, this process takes place in the large intestine.

4. Match the Item of Column I With Those Given in Column II.

Ans:

The food components we take contain carbohydrates, proteins, and fats, which are then broken down by the digestive system into digestible ones such as sugar, amino acids, and fatty acids, glycerol respectively.

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

Ans:

1. The finger-like projections present in the inner wall of the small intestine are called villi.

2. Villi serves the function of increasing the surface area of the small intestine for absorption of digested food. 

6. Where is the Bile produced? Which component of the food does it digest?

Ans:

1. Bile is produced by the liver. The gallbladder is where it is stored temporarily.

2. Fat is the component of food that is digested by bile juices.

7. Name the carbohydrate that can be digested by ruminants but not human beings. Give reason also.

Ans: Cellulose can be digested by ruminants but not by human beings. Because ruminants have a large sac-like structure called rumen between the esophagus and the small intestine. The cellulose of the food is digested here by the action of certain bacteria which are not present in humans.

8. Why do we get instant energy from glucose?

Ans: Glucose is the simplest carbohydrate that undergoes oxidation and   can be broken easily to give a high energy molecule that provides energy for cells and the bloodstream by which we get instant energy 

9. Which part of the digestive canal is involved in:

• Absorption of food ------------. 

• Chewing of food -------------. 

• Killing of Bacteria ---------- 

• Complete digestion of food -----------. 

• Formation of feces -----------. 

Ans: 

• small intestine 

• buccal cavity 

• stomach 

• small intestine 

• large intestine 

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

Ans: Similarity: Both humans and amoeba require food for the cellular processes. Difference: Amoeba takes food by pseudopodia and digests it in there while humans eat food which gets digested at different parts of the digestive tract. 

11. Match the items of Column I With Suitable Items in Column II.

Ans:

12. Label fig. 2.2 of the Digestive System. 

(Image will be uploaded soon)

Ans:

(Image will be uploaded soon)

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

Ans:

1. No, we cannot survive only on raw, leafy vegetables/grass, because to live a healthy life we should have a balanced diet with all the nutrients.

2. Raw vegetables and grasses only provide fibers that are not enough for the body. So, these green leafy vegetables will not serve the purpose.

Class 7 Science Chapter 2 Nutrition in Animals – Free PDF Download

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The NCERT Solutions of Chapter 2 of CBSE Class 7 Science given in this free downloadable PDF will benefit the students in understanding how to frame an answer in the exams, and it will also explain the concepts of animal nutrition in a better and comprehensive way. The detailed summary of the chapter at the end with key points to remember will come in handy when students look for quick revision.

So, download these NCERT Solutions For Class 7 Science Chapter 2: Nutrition in Animals today for better knowledge and performance. 

2.1 Different Ways of Taking Food

NCERT Science Class 7 Chapter 2 PDF download for Nutrition in Animals Class 7 will allow students to focus on how food is consumed. Different organisms have specific ways of consuming food. When it comes to bees and hummingbirds, they prefer sucking the nectar of plants. In terms of humans and other mammals, infants feed on mothers’ milk. Snakes find their prey and swallow them entirely. Among the aquatic animals, some of them find little food particles freely floating in the water and feed on them.

2.2 Digestion in Humans

Human beings consume their food with the help of the mouth. The food particles are then digested and utilized for various bodily functions. The ingested food that remains undigested gets defecated. What exactly happens after the food is chewed and swallowed? 

The food enters the stomach through a continuous canal that starts at the buccal cavity and ends at the anus. This canal is divided into several parts which include:

• The buccal cavity

• Food pipe or Esophagus

• Stomach

• Small intestine

• Large intestine ending in the rectum

• The anus

These parts together make the alimentary canal or the digestive tract. When the food travels through the different compartments of the canal, it gradually gets digested and reaches our system. The digestion process is done through secretion of digestive juices from the inner walls of the stomach, small intestine and other glands that are associated with the digestion process including salivary glands, pancreas and the liver. The digestive juice makes the digestion process easier by breaking the food particles into simpler forms. Now, let’s find out what happens to the food in the various parts of the digestive tract?

The Mouth and Buccal Cavity

Whatever food we eat, it is taken into the body through our mouth. This process of taking the food into the body is known to be ingestion. The teeth in our mouth help in chewing and further break down mechanically to form tiny particles. Each root of a tooth has a separate socket that goes right into the gums. Even teeth are categorized based on their functionalities and appearance. These functionalities are:

• Cutting and biting

• Piercing and tearing

• Chewing and grinding

Milk Teeth and Permanent Teeth

The first set of teeth that grow during infancy are known as milk teeth. They fall off between the age of six to eight years. Each tooth comes off from the root randomly to replace it with a permanent tooth. These sets of teeth may last the entire life or fall off when an adult becomes old enough. Permanent teeth may also come off due to dental diseases.

Sweets and Tooth Decay

Usually, bacteria can be found in our mouths, but they are not always harmful. However, if we do not take care of our teeth and gums, these bacteria can start creating ill effects. They tend to find a good place and grow between the gaps and crevices of your teeth.

Therefore, it is crucial to thoroughly clean and floss your mouth after every meal. The bacteria harm our teeth by releasing acids, which is used for breaking down sugar from the leftover food particles inside the mouth. This process is called tooth decay. If it’s overlooked, over time, tooth decay can cause severe toothache or loss of the tooth.

Chocolates, candies, soft drinks and other sugar products are the sources of causing tooth decay. Therefore, it is pivotal to clean your teeth with a brush and also use a tongue scraper for cleaning accumulated bacteria from the pores of the tongue. Using dental floss is also a good consideration to extract trapped food particles between two teeth. Make sure not to put unwashed or dirty fingers inside your mouth.

The Food Pipe/Esophagus

After the food is swallowed, it passes through a food pipe or esophagus. The food pipe starts from the neck to the ends of the chest. Basically, it connects our stomach with the neck. In the food pipe, through the movement in the wall, food is pushed down to the stomach. Actually, this movement is very common in the entire alimentary canal as the system continuously tends to push the food downwards. Sometimes, based on specific situations and types of food, our stomach does not accept the ingested food particles and this causes vomiting.

The Stomach

The stomach is known to be a large compartment in the alimentary canal. It is a thick-walled bag that looks like a flattened U. This part is the broadest in the entire canal. Our stomach receives food from one end (food pipe) and releases it to the other. The other opening leads the food particles to the small intestine. There is the inner lining of the wall inside the stomach and secretes mucus, hydrochloric acid and digestive juices to extract the contents from the food, for example, protein, carbohydrates, minerals, water, and others. The internal lining of the stomach is protected by the mucus, and the acid released is responsible for killing different types of bacteria which enter along with the food. The digestive juice naturally digests the core contents of the food. It further helps to break proteins in a simpler version of substances.

Small Intestine

The small intestine is known to be the tube that is extremely coiled and measures around 7.5 meters long. The secretion from the liver and pancreas reaches into the small intestine. Also, the inner wall of the intestine secretes juice to digest the remaining part of the food. The liver secretes bile, which is stored in a large sac known as the gallbladder. Bile is an important part of digestion, especially when it comes to fats. The half-digested food then reaches to the lower part of the intestine to complete the last stage of digestion.

Absorption in the Small Intestine

All digested food passes through the wall of the intestine to enter our blood vessels. This is known as absorption. The inner wall of the intestine is filled with finger-like outgrowths called villi. They are responsible for increasing the surface area to absorb the digested food.

Large Intestine

The large instance is a bit wider and shorter when compared with the small intestine. It measures about 1.5 meters long. It is responsible for absorbing water and salts from the undigested food particles. The undigested food, in the form of waste, passes to the rectum. They are stored like semi-solid feces. Fecal matters are then removed out of the body through the anus. The procedure is called egestion.

Diarrhea

Sometimes when our digestive system fails, it leads to diarrhea. This may trigger an infection, indigestion or food poisoning. This is a very common case in children, and under severe conditions, it may turn out to be fatal. The excessive loss of salt and water from the body can be harmful to us.

Key Points at a Glance

Let us look into some of the important takeaways of the chapter.

• Animal nutrition encompasses nutrient requirements, food consumption methods, and food usage in the body.

• The gastrointestinal tract and secretory glands make up the human digestive system.

• The salivary glands, the liver, and the pancreas are the parts of the glandular system that secrete digestive juices.

• Digestive enzymes are also produced by the stomach and intestinal tract walls.

• Carbohydrate digestion, such as starch digestion, begins in the buccal cavity.

• Protein digestion begins in the stomach.

• In the small intestine, bile, pancreatic juice and digestive juice accomplish the digestion of all ingested elements.

• The small intestine absorbs the digested food through the blood vessels.

• The large intestine absorbs water and salts from the undigested material.

• Through the anus, the unabsorbed leftovers are ejected from the body as faeces.

• Ruminants are grazing animals such as cows, buffaloes, and deer.

• They quickly ingest and retain their green diet in the rumen. The meal eventually returns to the animal's mouth, where it is chewed.

• The meal is ingested by the amoeba using its false feet, or pseudopodia. The food vacuole is where the meal is processed.

NCERT Solutions Class 7 Science Chapters

• Chapter 1 - Nutrition in Plants

• Chapter 3 - Fibre to Fabric

• Chapter 4 - Heat

• Chapter 5 - Acids

• Chapter 6 - Physical and Chemical Changes

• Chapter 7 - Weather

• Chapter 8 - Winds

• Chapter 9 - Soil

• Chapter 10 - Respiration in Organisms

• Chapter 11 - Transportation in Animals and Plants

• Chapter 12 - Reproduction in Plants

• Chapter 13 - Motion and Time

• Chapter 14 - Electric Current and Its Effects

• Chapter 15 - Light

• Chapter 16 - Water: A Precious Resource

• Chapter 17 - Forests: Our Lifeline

• Chapter 18 - Wastewater Story

Additional Materials for CBSE Class 7 Science 

• CBSE Class 7 Important Questions

• CBSE Class 7 Revision Notes

• CBSE Class 7 Exemplar Solutions

Key Features of NCERT Solutions for Class 7 Science Chapter 1

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