DAV Class 7 Science Chapter 2 Question Answer – Nutrition in Living Organisms: Animals and Man

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DAV Class 7 Science Ch 2 Question Answer – Nutrition in Living Organisms: Animals and Man

DAV Class 7 Science Ch 2 Solutions – Nutrition in Living Organisms: Animals and Man

Something to now

A. Fill in the blanks.

Question 1.
The digestion of food in humans starts in the ________ and is completed in the ________
Answer:
Mouth, Small intestine

Question 2.
________ present in stomach, kills bacteria.
Answer:
Hydrochloric Acid

Question 3.
The largest gland in the human body is the ________
Answer:
Liver

Question 4.
Partially digested food, that is chewed again by grass eating animals, is called the………….
Answer:
Cud

Question 5.
Amoeba uses ________ for locomotion and for capturing its food.
Answer:
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:

1. Gall bladder	a	Bile juice
2. Proteins	e	Cow
3. Intestinal wall	c	Absorption
4. Rumen	b	False feet
5. Pseudopodia	d	Amino acids

C. Tick (✓) the correct option.

1. Organisms, that can synthesise their own food, are called—
(a) Heterotrophs
(b) Parasites
(c) Autotrophs
(d) Saprotrophs
Answer:
(c) Autotrophs

2. Cow is a/ an –
(a) Saprotroph
(b) Parasite
(c) Autotroph
(d) Heterotroph
Answer:
(d) Heterotroph

3. Animals, that eat both plant materials and animals, are called
(a) Herbivores
(b) Omnivores
(c) Carnivores
(d) Ruminants
Answer:
(b) Omnivores

4. Which one of these is not a part of the alimentary canal?
(a) Stomach
(b) Anus
(c) Liver
(d) Large intestine
Answer:
(c) Liver

5. Bile juice is released by the
(a) Salivary glands
(b) Pancreas
(c) Liver
(d) Large intestine
Answer:
(c) Liver

D. Answer the following questions in brief.

Question 1.
Define the following terms:
(a) Holozoic nutrition
Answer:
The mode of nutrition in which an animal ingests its food and digestion happens inside the body of the organism is called holozoic nutrition.

(b) Alimentary canal
Answer:
Alimentary canal is a hollow tube which begins from the mouth and ends in the anus.

Question 2.
Give the meaning of the terms:
(a) Assimilation
Answer:
The utilization of absorbed food for growth and repair is called assimilation.

(b) Rumination
Answer:
The process of chewing cud by grass eating animals is called rumination.

Question 3.
Name the organs that make up the human alimentary canal.
Answer:
Mouth, oesophagus, stomach, small intestine, large intestine, rectum, anus

Question 4.
State two differences between milk teeth and permanent teeth.
Answer:

Milk Teeth	Permanent Teeth
They drop out during childhood.	They never drop out.
They are less in number.	They are more in number.

Question 5.
Name the four types of teeth in the human mouth.
Answer:
Incisor, canine, premolar and molar.

Question 6.
State the function of the (a) incisor teeth (b) premolar teeth.
Answer:
(a) Incisor teeth are for cutting the food, (b) Premolar teeth are for grinding the food.

Question 7.
State the role of acid in the human stomach.
Answer:
Role of acid in human stomach is as follows:

• It kills any germ in food.
• It is necessary for digestive enzymes’ working in the stomach.

Question 8.
State the function of (a) bile juice and (b) pancreatic juice in the human digestive system.
Answer:
Bile juice helps in digestion of fat. Enzymes in small intestine work better in presence of bile. Pancreatic juice contains many digestive enzymes which digest food.

E. Answer the following questions.

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

Question 2.
Justify the following statements:
(a) Crow is an omnivore.
Answer:
Crow is an omnivore because it eats both plants and animals. So, this statement is true. .

(b) It is said that mode of nutrition, in human beings and Amoeba is quite similar.
Answer:
Both amoeba and human beings follow bolozoic mode of nutrition; in which food
is ingested and digestion happens inside the body of the organism. Hence, it can be said the mode of nutrition in human beings and amoeba is similar.

Question 3.
Give reasons for the following:
(a) Ingestion of food is difficult without teeth.
Answer:
Teeth help in breaking the food into small pieces; which makes it easier to swallow. In the absence of teeth, it would be very difficult to swallow the food. Hence, ingestion of food is difficult without teeth.

(b) If we chew rice, or bread, for a few minutes, it starts tasting sweet.
Answer:
When we chew rice or bread for a few minutes, the digestive enzyme in saliva works on starch and changes it into sugar. Sugar has sweet taste. Hence, after being chewed for some time, rice or bread starts tasting sweet.

(c) Bacteria are present in the caecum of ruminants.
Answer:
Bacteria are present in the rumen of ruminants and not in the caecum.

Question 4.
Explain how digested food gets absorbed into the blood.
Answer:
The wall of the small intestine absorbs the digested food, then absorbed food enters the blood.

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

• Grass eating animals quickly swallow the food and store it in rumen.
• After partial digestion in rumen, the food comes back to mouth; in the form of lumps. It is called cud.
• Then the animal properly chews the cud and then the food is sent for further digestion.

Question 6.
Explain ingestion of food, in amoeba, through a diagram.
Answer:
Amoeba surrounds a food particle by pseudopodia. Then it makes a food vacuole which contains food and water. That is how ingestion takes place in amoeba.

Value Based Question

The biology teacher, who was also the coach of the school cricket team, would often compare his team members with the different ‘organs’ of their digestive system. He would tell them to concentrate on their respective roles and to work as a team in a selfless and dedicated way. This, he would say, would enable them to succeed in winning matches in the same way as the ‘team’ of the organs of the digestive system, ‘succeeds’ in digesting, and using, the ‘ingested food’.

Question 1.
State two of the values that the teacher wanted his students to ‘have in them’.
Answer:
Teamwork and selfless attitude

Question 2.
Try to make a list of ‘eleven names’ that are part of the ‘team’ that makes up the human digestive system.
Answer:
Mouth, oesophagus, stomach, small intestine, large intestine, teeth, tongue, salivary gland, liver, pancreas and gall bladder.

Question 3.
Have a group discussion on the importance of Team Work’ in day-to-day life.
Answer:
Do it yourself.

Something To Do

Question 1.
Make a PowerPoint presentation on the various ways in which animals ingest
their food. For example: [Herbivores – cow, Carnivores – Lion, Blood suckers – Leech, Fruit eating – birds, Fluid feeders – Butterflies, moth, earthworm; Insectivore – Frog]
Answer:
Do it yourself.

Question 2.
Collect data, from the parents of your five classmates, about their milk teeth. Tabulate your data as given below:

Name	Age at which first tooth fell	Age at which last tooth fell	No. of teeth lost	No. of teeth replaced

Use the collected data, to estimate the average age at which children lose their milk teeth.
Answer:
Do it yourself.

Question 3.
Make a model of the digestive system (using clay/plasticine to make the organs) and rubber pipes/ribbons to make the food pipe and small intestine.
Answer:
Do it yourself.

Question 4.
Activity-Assign a particular organ of the digestive system to each student and ask them to enact the role of it. The students need to follow the given guidelines. They should introduce themselves as a particular organ, explain its structure and function, its importance and significance in the human body and name some diseases, associated with the ‘organs’, represented by them. The teacher can judge their role play by considering their presentation, content, visual aid used, clarity of concepts, etc.
Answer:
Do it yourself.

DAV Class 7 Science Chapter 2 Solutions – Nutrition in Living Organisms: Animals and Man

I. Fill in the blanks.

Question 1.
In ________ nutrition, food is ingested before digestion.
Answer:
Holozoic

Question 2.
In ________ nutrition, food is ingested after digestion.
Answer:
Saprophytic

Question 3.
Partial digestion of ________takes place in stomach.
Answer:
Protein

Question 4.
Complete digestion of food takes place in ________
Answer:
Small intestine.

Question 5.
Rumen is a chamber in ________ of ruminating animals.
Answer:
Small intestine

Question 6.
Digestion of food in amoeba takes place in ________
Answer:
Food vacuole

Question 7.
Partially digested food that is chewed again by grass eating animals is called ________
Answer:
Cud

Question 8.
Amoeba uses ………… for locomotion.
Answer:
Pseudopodia

II. Tick (✓) the correct option.

1. Which of these animals is a parasite?
(a) Amoeba
(b) Hook worm
(c) Cockroach
(d) Vulture
Answer:
(b) Hook worm

2. Saliva converts starch into which of these?
(a) Carbohydrate
(b) Protein
(c) Sugar
(d) Fat
Answer:
(c) Sugar

3. Which type of teeth is used for tearing the food?
(a) Incisors
(b) Canines
(c) Premolar
(d) Molar
Answer:
(b) Canines

4. How many incisors are there in a normal adult human?
(a) 2
(b) 4
(c) 6
(d) 8
Answer:
(b) 4

5. Which of these is a ruminating animal?
(a) Lion
(b) Fox
(c) Cat
(d) Cow
Answer:
(d) Cow

III. Answer the following questions in brief.

Question 1.
How does animal nutrition differ from plant nutrition?
Answer:
The green plants show autotrophic nutrition, while the animals show heterotrophic nutrition. Holozoic nutrition is present in animals only and not in plants.

Question 2.
Define the following terms:
(a) Omnivore
Answer:
Animals which eat both animal flesh and plant materials are called omnivores, e.g. bear and man.

Question 3.
What are the functions of the tongue?
Answer:
Taste buds are present on tongue and help us in getting the sensation of test. Tongue also helps in mixing the saliva with food.

Question 4.
How is food digested in grass eating animals?
Answer:
Grass eating animals are called ruminants. There are four chambers in their stomach. The first chamber is the largest and is called rumen. Some microorganisms live in the rumen and help in digestion of cellulose. Grass eating animals quickly swallow the food and store it in rumen. After partial digestion in the rumen; the food comes back to mouth; in the form of small lumps. This food is called cud. The animal then chews the cud properly and hence is called cud-chewing or ruminating animals. It is important to note that without the help of certain microorganisms, tnese animals cannot digest cellulose.

Question 5.
How does amoeba obtain its nutrients?
Answer:
Amoeba is a unicellular organism which shows holozoic nutrition. Pseudopodia keep on forming and disappearing on the body of an amoeba. Amoeba surrounds the food particle with its pseudopodia and makes a food vacuole around the food particle. The food; along with water; is thus taken inside the food vacuole. Digestion and absorption takes place in the food vacuole. After that, the food vacuole expels undigested food.

Question 6.
Find out the number of milk teeth and permanent teeth in human beings.
Answer:
There are 20 milk teeth and 32 permanent teeth in human beings.

Question 7.
The doctor prescribed antibiotics to cure infections in the body even though the infection may be on a finger or external body part, the antibiotic has to be taken orally (by mouth). What could be the reason?
Answer:
We know that, whatever we eat, is absorbed by small intestine in its simple form and then goes to the blood stream. Thus, every substance reaches different parts of the body via blood stream. Medicines also follow similar path, i.e. they reach the site of infection through blood stream. Hence, no matter whether the infection is in finger or external body parts, the antibiotic usually needs to be taken orally.

Question 8.
Even though we cannot digest cellulose, still we are advised to eat salad and other food; containing plant fibres that are rich in cellulose. Why?
Answer:
Cellulose makes the roughage in our food; which helps in proper bowel movement. Due to this, we are advised to eat salad and other food which contain plant fibres and are rich in cellulose.

IV. Answer the following questions.

Question 1.
What do you understand by ingestion of food?
Answer:
The act of getting and eating food is called ingestion. Human beings take food through mouth.

Question 2.
What do you understand by digestion of food?
Answer:
The breakdown of complex molecules into simple soluble molecules is called digestion.

Question 3.
Write the names of various types of teeth and their functions.
Answer:
Various types of teeth and their functions are as follows:

• Incisors: These teeth are used for cutting the food.
• Canines: These teeth are used for tearing the food.
• Premolars: These teeth are used for grinding the food.
• Molars: These teeth are also used for grinding the food.

Question 4.
Explain the absorption of food in humAnswer:
Answer:
The inner wall of the small intestine has large number of finger-like projections; called villi. Villi increase the surface area for absorption of digested food. The digested food passes into blood vessels which are present in the villi.

Question 5.
Briefly explain the various steps of nutrition in human beings.
Answer:
Nutrition in human happens in the following steps:
(a) Ingestion: The act of getting and eating food is called ingestion. Human beings take food through mouth.

(b) Digestion: The breakdown of complex molecules into simple soluble molecules is called digestion. Digestion of food takes place with the help of certain chemicals which are called enzymes.

(c) Absorption: The digested food is absorbed by the wall of the small intestine. The absorbed food enters the blood supply and is sent to different parts of the body.

(d) Assimilation: The utilization of absorbed food for growth and repair is called assimilation.

(e) Egestion: Elimination of undigested food from alimentary canal is called egestion.

V. State whether the following statements are true or false.

1. Taking in of food is termed ingestion.
2. Stomach secretes hydrochloric acid.
3. Rectum helps in absorption of food.
4. Man is a ruminant.
5. Amoeba uses pseudopodia to ingest food.
Answer:
1. Taking in of food is termed ingestion. (True)
2. Stomach secretes hydrochloric acid. (True)
3. Rectum helps in absorption of food. (False)
4. Man is a ruminant. (False)
5. Amoeba uses pseudopodia to ingest food. (True)

VI. Projects:

Question 1.
Make a diagram of tongue and show different regions which are sensitive to different tastes.
Answer:
Do it yourself.

Question 2.
Make a list of five ruminating animals.
Answer:
Do it yourself.