Active Science Solutions for Class 7 Science Chapter 2 Food For Animals are provided here with simple step-by-step explanations. These solutions for Food For Animals are extremely popular among Class 7 students for Science Food For Animals Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Active Science Book of Class 7 Science Chapter 2 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Active Science Solutions. All Active Science Solutions for class Class 7 Science are prepared by experts and are 100% accurate.

Page No 20:

Question 1:

In which of the following organs will the digestion of starch take place?
(a) mouth
(b) stomach
(c) small intestine
(d) large intestine

Answer:

(a) mouth and (c) small intestine
In the mouth, the salivary amylase digests the starch, while in the small intestine, the pancreatic juice digests the starch.

Page No 20:

Question 2:

Which option shows the correct order involved in nutrition of animals.
1. egestion
2. ingestion
3. assimiltion
4. absorption
5. digestion

(a) 1-2-3-4-5
(b) 2-5-3-4-1
(c) 2-4-5-3-1
(d) 2-5-4-3-1

Answer:

(d) 2-5-4-3-1
Food is first ingested, it is then digested, absorbed, assimilated and, finally, thrown out of the body by egestion.



Page No 21:

Question 3:

Look at this diagram of the human digestive system with four organs labelled as A, B, C and D.
Figure

The Organs A, B, C and D are:
(a) A-oesophagus; B-large intestine; C-liver; D-stomach
(b) A-oesophagus; B-stomach; C-liver; D-large intestine
(c) A-oesophagus; B-liver; C-stomach; D-large intestine
(d) A-large intestine; B-stomach, C-liver; D-oesophagus

Answer:

(b) A-oesophagus; B-stomach; C-liver; D-large intestine

Page No 21:

Question 4:

Which one of the following is not heterotrophic?
(a) neem tree
(b) deer
(c) lion
(d) rabbit
      
  

Answer:

(a) neem tree
It is autotrophic as it can make its own food.

Page No 21:

Question 5:

Which one of the pairs given below is not correctly matched?
(a) gastric juice-pepsin
(b) bule-pancreas
(c) hydrochloric acid-stomach
(d) saliva-ptyalin

Answer:

(b) bile-pancreas
Bile is produced in the liver.

Page No 21:

Question 6:

What is common to the following:saliva, pancreatic juice, gastric juice
(a) All of them are organs of digestion.
(b) All of them contain enzymes that help in digestion.
(c) All of them help in digestion of fat.
(d) All of them are enzymes.

Answer:

(b) All of them contain enzymes that help in digestion.
Saliva has salivary amylase and gastric juice has pepsin, which are enzymes that aid in digestion.

Page No 21:

Question 7:

During a dental check up in school, the dentist asked a group of students to name the teeth from the back of the mouth to the front in the correct order. He got four different answers. Identify the one that shows the correct order.
(a) 3 incisors, 2 canines, 1 molar, 2 premolars.
(b) 2 incisors, 1 canine, 3 premolars, 2 molars.
(c) 2 molars, 3 premolars, 2 canines, 1 incisor.
(d) 3 molars, 2 premolars, 1 canine, 2 incisors.

Answer:

(d) 3 molars, 2 premolars, 1 canine, 2 incisors
The correct order of the teeth from the back of the mouth to the front is 3 molars, 2 premolars, 1 canine and 2 incisors.

Page No 21:

Question 8:

The process by which animals make use of the digestive food is called
(a) absorption.
(b) digestion.
(c) ingestion.
(d) assimilation.

Answer:

(d) assimilation
Assimilation is the process by which animals make use of the digestive food for their growth and development.

Page No 21:

Question 9:

The process of taking in food is also called
(a) ingestion.
(b) egestion.
(c) digestion.
(d) absorption.

Answer:

(a) ingestion
Ingestion is the process of taking in food.

Page No 21:

Question 10:

Describe the process of nutrition in
Amoeba.

Answer:

Nutrition in amoeba takes place in five steps:

During ingestion, Amoeba forms finger-like projections called pseudopodia that engulf the food and form a cavity called food vacuole. Digestion takes place in the food vacuole with the help of the digestive juices secreted by it. After digestion, food is absorbed and assimilated and the undigested food is egested out of its body.

Page No 21:

Question 11:

Explain why we cannot use our canine teeth for biting into apples or our incisors for chewing?

Answer:

Incisors are the sharp teeth in the front with chisel-like edges. Thus, they can be used for biting, but not for chewing. Canines are the large pointed teeth on the either side of the incisors. They cannot be used for biting as they are not present in the front.



Page No 22:

Question 12:

Differentiate between the process of ingestion in the Amoeba and human beings.

Answer:

Ingestion in Amoeba Ingestion in human beings
It ingests food by forming pseudopodia around it. Human beings ingest food through the mouth.

Page No 22:

Question 13:

Draw a labelled diagram of the alimentary canal in human beings.

Answer:

The human alimentary canal

Page No 22:

Question 14:

Find the odd one out from the following groups, giving reasons for your choice.
(a) bile, gastric juice, liver, pancreatic juice
(b) canine, molar, incisors, rumen
(c) stomach, roughage, intestine, liver

Answer:

(a) Liver is the odd one out as it is an organ, while the others are digestive juices.
(b) Rumen is the odd one out as it is a digestive organ, whereas the others are types of teeth.
(c) Roughage is the odd one out as it is food fibre, whereas the others are digestive organs.

Page No 22:

Question 15:

How is the process of digestion in ruminants different from that in human beings?

Answer:

The process of digestion in ruminants is different from that in human beings. They have three extra chambers in their stomach before the true stomach. The first chamber is the biggest and is called the rumen. In the rumen, food is made soft and pulpy with the help of cellulose digesting microbes. This partly digested food is brought back to the mouth and mixed with saliva from time to time. This is called rumination. After the food is swallowed again, it passes through the 3 chambers before it enters the actual stomach. After that, the digestion is same as that in human beings.

Page No 22:

Question 16:

It was found that the astronauts in a space ship had no difficulty in swallowing food even if they were upside down. Can you explain why? Can you swallow food when you are upside down on earth? Explain your answer.

Answer:

Food always passes down the gut, irrespective of our position. Food is pushed downwards from the oesophagus by the rhythmic contraction of the muscles of the oesophagus. This movement is called peristalsis, which does not allow the food to flow in the reverse direction. This is why we can swallow food when we are upside down on the Earth. Similarly, astronauts in a spaceship have no difficulty in swallowing food even if they are upside down.

Page No 22:

Question 17:

Give the functions of each of the following.
stomach, small intestine, large intestine, rumen in ruminants, saliva, bile, hydrochloric acid

Answer:

Stomach: Here, the digestion of proteins takes place.

Small intestine: Here, complete digestion of fats, carbohydrates and proteins take place. The food is also absorbed here.

Large intestine: It absorbs water and salts from the undigested food material.

Rumen in ruminants: It is the first chamber of the stomach in which food is made soft and pulpy.

Saliva: It has enzymes that partly digest the carbohydrates.

Bile: It helps in the digestion of fats.
 
Hydrochloric acid: It provides the acidic medium for the action of pepsin in the stomach.

Page No 22:

Question 18:

Why is the stomach wall not digested by its own enzymes?

Answer:

The wall of the stomach is lined with mucus, which protects the stomach from being digested by its own enzymes.

Page No 22:

Question 19:

Arrange the following in the order in which they are found in the alimentary canal.
small intestine, mouth, anus, large intestine, duodenum, oesophagus, stomach

Answer:

The correct order in which the given organs are found in the alimentary canal is:
mouth, oesophagus, stomach, duodenum, small intestine, large intestine and anus

Page No 22:

Question 20:

Define the following: enzyme, digestion, assimilation, constipation.

Answer:

Enzyme is a biological catalyst that helps reactions to take place. It remains unchanged after the reaction.
Digestion is the breaking down of complex molecules to simple soluble forms.
Assimilation is the use of absorbed food by the body to make new cells, repair the old ones and obtain energy.
Constipation is the drying and hardening of faeces.

Page No 22:

Question 21:

If you had I dal and a parantha for yours breakfast, name the nutrient components of the meal. Also write down how each one is digested.

Answer:

Dal is a pulse and is rich in proteins. Parantha is made up of wheat, which is a source of carbohydrate.
The digestion of carbohydrates begins in the mouth itself. The enzyme salivary amylase of the saliva digests starch into simple sugars. The food is then passed into the stomach. In the stomach, proteins are digested by the enzyme pepsin in presence of hydrochloric acid. After this, the food enters the small intestine. Here, bile makes the food alkaline and it is further digested by enzymes. In the small intestine, the digestion is completed and the carbohydrates get converted into simple sugars and the proteins into amino acids.

Page No 22:

Question 22:

List the functions of the liver.

Answer:

The functions of the liver are as follows:

  • It secretes bile.
  • It stores excess glucose in the form of glycogen.
  • It removes toxic poisonous substances from the body and also breaks down bacteria.

Page No 22:

Question 23:

Give scientific reasons for the following:
(a) Cats have well-developed canines.
(b) Hydrochloric acid produced in the stomach makes the food acidic besides killing germs and  dissolving bones.

Answer:

(a) Cats have well-developed canines because they eat the flesh of other animals like rats. Canines are large pointed teeth meant for shearing flesh and meat.
(b) Besides killing germs and  dissolving bones, hydrochloric acid produced in the stomach makes the food acidic. This helps the proteins in the food to be digested by pepsin, which is active only in an acidic medium.

Page No 22:

Question 24:

A child was asked to count his teeth. The number was twenty.
(a) Name the kind of teeth that are present.
(b) How many teeth are there in an adult human being?
(c) What kind of teeth are missing in a child though they are found in an adult?

Answer:

(a) The child has three types of teeth, i.e. incisors, canines and pre-molars.
(b) An adult human being has 32 teeth.
(c) Molars are present in an adult but not in a child.

Page No 22:

Question 25:

The functions of the organs of digestion are listed below. Write the name of one organ from the lost against each phrase stomach, liver, small intestine, oesophagus, mouth, large intestine.
(a) no digestion takes place here _________________
(b) food is partly digested here in an acidic medium ________________
(c) digest and also absorbs food _______________
(d) takes food from the mouth to the stomach _______________
(e) starch is partly digested here ________________
(f) produces bile __________________

Answer:

(a) no digestion takes place here oesophagus
(b) food is partly digested here in an acidic medium stomach
(c) digests and also absorbs food small intestine
(d) takes food from the mouth to the stomach oesophagus
(e) starch is partly digested here mouth
(f) produces bile liver



Page No 23:

Question 26:

Arrange the pictures showing the sequence of nutrition in the Amoeba in the correct order.
Figure

Answer:

The correct order is b, d, a, c.

Page No 23:

Question 27:

figure

Where do you think the protein will be digested and why?

Answer:

The proteins will be digested in test tube b as it has the enzyme pepsin to digest proteins and hydrochloric acid to provide the acidic medium required for the activity of pepsin.

Page No 23:

Question 28:

Copy this table in your notebook  and complete it.
 

Organs Food Component   End Product of Digestion
mouth                 carbohydrates  
stomach   amino acids
small intestine   simple sugars
  fats  
  proteins  

Answer:

Organs Food Component   End Product of Digestion
mouth carbohydrates sugars
stomach proteins amino acids
small intestine carbohydrates simple sugars
small intestine fats fatty acids
small intestine proteins amino acids

Page No 23:

Question 29:

Prachi performed an experiment as shown below.
figure

Study the two figures carefully. On adding iodine, only the mixture in test tube A changed to blue black whereas the mixture in test tube B remained the same colour. Can you say why?

Answer:

Test tube A has only boiled rice, which has starch. Hence, it gives a blue-black colour on reaction with iodine. Test tube B has chewed rice mixed with saliva. The enzyme present in saliva digests the starch into sugars. Hence, the colour of the mixture does not change on adding iodine.



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