DAV Class – 7 Science Chapter – 2 Solutions

DAV Class – 7 Science Chapter – 2 Solutions: Student who are looking for the solutions of dav class 7 science book chapter 2 Nutrition in Living Organisms-Animals and Man then you are at right place. Here we provide complete solution of DAV School class Seven the Living World science book.

DAV Class – 7 Science Chapter – 2 Solutions

DAV class 7 science chapter 2 solution Nutrition in Living Organisms-Animals and Man is given below. Here class 7 Science Question Answer is provided with great explanation.

Highlights

• A. Fill in the blanks.
• B. Match the following:
• C. Tick the correct option.
• D. Answer the following questions in brief.
• E. Answer the following questions.

A. Fill in the blanks.

1. The digestion of food in humans starts in the ___________ and is completed in the ___________.

2. ___________, present in the stomach, kills bacteria.

3. The largest gland in the human body is the ___________.

4. Partially digested food, that is chewed again by grass eating animals, is called the ___________.

5. Amoeba uses ___________ for locomotion and for capturing its food.

Answer:

(1) mouth, small intestine (2) Hydrochloric acid (3) liver (4) cud (5) pseudopodia

B. Match the following:

1. Gall bladder             (a) Bile Juice

2. Proteins                   (b)  Cow

3. Intestinal wall          (c) Absorption

4. Rumen                     (d) False feet

5. Pseudopodia           (e) Amino acids

Answer:

C. Tick the correct option.

Answer:

(1) autotrophs (2) heterotroph (3) omnivores (4) liver (5) liver

D. Answer the following questions in brief.

1. Define the following terms:

(a) Holozoic nutrition

Answer:

This is a mode of nutrition, in which organisms, like Amoeba and human beings, eat food that may be in solid or in liquid state.

(b) Alimentary canal

Answer:

Alimentary canal is the long muscular tube in the human body through which food passes after its ingestion.

2. Give the meaning of the terms:

(a) Assimilation

Answer:

The absorbed food is utilised by the body for growth and formation of body parts. This process is known as assimilation.

(b) Rumination

Answer: The process of chewing cud thoroughly is called rumination.

3. Name the organs that make up the human alimentary canal.

Answer: The organs that make up the human alimentary canal are: 

(1) Mouth and Buccal cavity (2) Food pipe (or Oesophagus) (3) Stomach (4) Small intestine (5) Large intestine (6) Anus.

4. State two differences between milk teeth and permanent teeth.

Answer:

Two differences between milk teeth and permanent teeth are: – 

Milk teeth

(1) They start appearing, above the gumline, when a baby is six, or seven months old.

(2) They are 20 in numbers.

Permanent teeth

(1) They start appearing when a child is around the age of 6 years. 

(2) They are 32 in numbers.

5. Name the four types of teeth in the human mouth.

Answer:

The four types of teeth found in the human mouth are: 

(1) Incisors (2) Canines (3) Premolars (4) Molars

6. State the function of the (a) incisor teeth (b) premolar teeth.

Answer:

(a) Incisors are used for cutting the food.

(b) Premolars are used for grinding the food.

7. State the role of acid in the human stomach.

Answer:

The role of acid in the human stomach is to kill the bacteria and also provide the acidic medium, needed for the digestion of food by the enzymes in the stomach.

8. State the function of (a) bile juice and (b) pancreatic juice in the human digestive system.

Answer:

(a) The bile juice plays an important role in digestion of fats. 

(b) The pancreatic juice acts on carbohydrates, proteins and fats and breaks them into simpler forms.

E. Answer the following questions.

1. Draw a neat, well labelled diagram of the human digestive system.

Answer. For Diagram see page no. 17 of your book.

2. Justify the following statements:

(a) Crow is an omnivore.

Answer: Crow is an omnivore because it feeds on both plants and animal’s materials.

(b) It is said that the mode of nutrition, in human beings and Amoeba, is quite similar.

Answer:

Yes, Nutrition in human beings and Amoeba is quite similar i.e., holozoic mode of nutrition. They eat food that may be in solid or in liquid form.

3. Give reasons for the following:

(a) Ingestion of food is difficult without teeth.

Answer:

Ingestion of food is difficult without teeth because it breaks down the food into smaller pieces which are easy to swallow.

(b) If we chew rice, or bread, for a few minutes, it starts tasting sweet.

Answer:

If we chew rice, or bread, for a few minutes, it starts tasting sweet because saliva present in our mouth break down starch into sugar.

(c) Bacteria are present in the caecum of ruminants.

Answer: Bacteria present in the caecum help in the digestion of the cellulose of the food.

4. Explain how digested food gets absorbed into the blood.

Answer:

The inner wall, of the small intestine, absorbs the digested food. It has a large number of finger-like projections, called villi. The villi increase the effective surface area for absorption of digested food. This absorbed food is passed to blood vessels, present in the villi.

5. State, in one/two sentence/s each, the various processes involved in nutrition in ruminant animals.

Answer:

The various processes involved in nutrition in ruminant animals are:

(1) The animals first swallow the food quickly and store it in their rumen. The rumen has some micro-organisms that help in partial digestion of the cellulose of the plant materials. This food is now called cud. 

(2) The ruminants, later on, bring this cud back to their mouth and chew it thoroughly. This process is called rumination. 

(3) The thorough chewing of food during rumination, helps to break down the rich cellulose content of the plant materials. 

(4) Ruminants also have a spacious bag-like structure, between their small intestine and the large intestine. This is called caecum. The bacteria, present in the caecum, help in further digestion of the cellulose of the food.

6. Explain ingestion of food, in amoeba, through a diagram.

Answer:

When Amoeba comes in contact with food, it produces pseudopodia around the food particle. As the cell membranes of the pseudopodia fuse, the food gets trapped in a food vacuole. Digestive juices are secreted into this vacuole to digest the food.

For diagram, see page number 24 of your book.