Here in this post we provided NCERT Exemplar Problem Class 7 Science Nutrition in Animals Chapter 2 Full Explanation by group of Science Experts. We have provided here each questions answer with reason behind the answer.
Hope it help you!
Nutrition in Animals Class 7 Exemplar full Explanation:
1) Given below from (I) and ( IV) are some food items.
i) Boiled and mashed potato
ii) Glucose solution
iii) A slice of bread
iv) Mustard oil
Which of the above will give blue- black colour when tested with iodine?
a) i and ii b) i and iii
C) ii and iii. d) iii and iv
Answer:- b) I and III
Boiled and mashed potato contains starch. Which gives blue – black colour when reacts with iodine.
2.) Which of the following pair of teeth differ in structure but are similar in function?
a) Canines and incisors
b) Molars and premolars
c) Incisors and molars
d) Premolars and canines
Answer:-b) molars and premolars
Molars and premolars have the different structure but is same in function which is chewing and grinding.
3.) Read carefully the terms given below. Which of the following set is correct combination of organs that do not carry out any digestive functions?
a) Oesophagus, Large intestine, Rectum
b) Buccal cavity, Oesophagus, Rectum
c) Buccal cavity, Oesophagus, Large intestine
d) Small intestine, Large intestine, Rectum
Answer:- a) oesophagus, large intestine , Rectum
The oesophagus, large intestine and Rectum all three does not carry out any digestive functions. While the buccal cavity in (b) , and (c) , and small intestine in (d) carry out the digestive functions.
4.) The swallowed food moves downwards in the alimentary canal because of
a) Force provided by the muscular tongue.
b) The flow of water taken with the food
c) Gravitational pull
d) The concentration of muscles in the wall of food pipe.
Answer:-d) the concentration of muscles in the wall of food pipe.
The swallowed food moves downwards in the alimentary canal because of the concentration of muscles in the wall of food pipe. The remaining reasons are not responsible for the swallowing food moving downward.
5.) The acid present in the stomach
a) Kills the harmful bacteria that may enter along with the food.
b) Protects the stomach lining from harmful substances.
c) Digest starch into simpler sugars.
d) Makes the medium alkaline.
Answer:- a) kills the harmful bacteria that may enter along with the food .
The HCl i.e hydrochloric acid present in stomach kills the harmful bacteria that may enter along with the food. High level of HCl causes acidity.
6.) The finger like outgrowths of Amoeba helps to ingest food. However, the finger like outgrowths of human intestine helps to
a) Digest the fatty food substances
b) Make the food soluble.
c) Absorb the digested food.
d) Absorb the undigested food.
Answer:- c) Absorb the digested food.
Amoeba have finger like outgrowths which is known as pseudopodia which help them to catch food and in movement also. But in human,finger like outgrowths of Small intestine are called Villi. Villi are present in thousands of number in intestine. These villi increases the surface area for absorption of the digested food. And thus the absorption of digested food is done by the villi.
7.) Read the following statement with reference to the villi of small intestine.
I) They Have very thin walls.
II) They have a network of thin and small blood vessels close to the surface.
III) They have small pores through which food can easily pass.
IV) They are finger like projections.
Identify those statements Which enable the villi to absorb digested food.
a) I,II andIV b) II , III and IV
C) III and IV. d) I and IV
Answer:- a) I , II and IV
Villi are present in small intestine in large number. These Villi have very thin walls , they have a network of thin and small blood vessels close to the surface. Villi are finger like projection of small intestine, But they don’t have pores. Villi plays an important role in the absorption of the digested food.
8) The false feet of Amoeba are used for
a) Movement only
b) Capture of food only
c) Capture of food and movement
d) Exchange of Gases only
Answer:- c) capture of food and movement
The false feet of Amoeba is also known as pseudopodia. Pseudopodia helps in capturing food and also in movement from one place to another.
9.) The enzyme present in the saliva convert.
a) Fats into fatty acids and glycerol
b) Starch into simple sugars.
c) Proteins into amino acids.
d) Complex sugars into simple sugars.
Answer:- b) starch into simple sugars.
The salivary glands which secrets saliva contains enzymes which convert starch into simple sugars.
10.) Cud is the name given to the food of ruminants which is
a) Swallowed and undigested
b) Swallowed and partially digested
c) Properly chewed and partially digested.
d) Properly chewed and completely digested.
Answer:- b) swallowed and partially digested.
Cud is the swallowed and partially digested food substance, which is present in rumen of ruminants animals. When the ruminants swallow grass hurriedly , it forms cud and then these cud is again come in mouth which is then finely grind and swallow again by ruminants these process is called rumination.
11.) Choose the correct order of terms that describes the process of nutrition in ruminants.
a) Swallowed→ partial digestion→ chewing of cud → complete digestion.
b) Chewing of cud → swallowing→ partial digestion → complete digestion.
c) Chewing of cud → swallowing → mixing with digestive juices → digestion.
d) Swallowing → chewing and mixing → partial digestion → complete digestion.
Answer:-a) swallowed → partial digestion → chewing of cud → complete digestion .
These is the correct order of ruminants in the process of nutrition.
12.) Cellulose –rich food substances are good source of roughage in human beings because
a) Human beings do not have cellulose – digesting enzymes.
b) Cellulose gets absorbed in the human blood and converts into fibres.
c) The cellulose – digesting bacteria convert cellulose into fibres.
d) Cellulose breaks down into smaller components which are egested as roughage.
Answer:- a) Human beings do not have cellulose – digesting enzymes.
Human beings cannot digest cellulose as we don’t have cellulose digesting enzymes, therefore it is a good source of roughage in human beings.
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Very Short Answer Questions
13.) Name the parts of the alimentary canal where
I) Water gets absorbed from undigested food.
II) Digested food gets absorbed
III) Taste of the food is perceived
IV) Bile juice is produced.
Answer:- these are the parts of alimentary canal where,
I) water gets absorbed from undigested food = large intestine
II) Digested food gets absorbed = small intestine
III) Taste of the food is perceived = tongue
IV) Bile juice is produced = Liver
14.) Mark the following statements as true or false. If false , write the correct statement.
a) Tongue is attached toroof of the mouth cavity at the back.
b) The large intestine is longer and wider than the small intestine of the human alimentary canal.
c) Mucus protects the stomach lining from damage.
d) All heterotrophs have a similar basic process of nutrition.
Answer:-
A) False
Correct statement:- Tongue is attached to the floor of the mouth cavity at the back.
B) False
Correct statement :- the large intestine is shorter and wider than the small intestine of the alimentary canal.
C) True
D) True
Choose the odd one out from each group and give reasons.
a) Liver, salivary gland,starch, gall bladder
b) Stomach, liver, pancreas, salivary gland
c) Tongue, absorption, taste, swallow
d) Oesophagus, small intestine, Large intestine, Rectum
Answer:-
A) Liver, salivary gland, starch, gall bladder
Odd word :- starch
Remaining are glands.
B) Stomach, liver , pancreas, salivary gland
Odd word :- stomach
Remaining are digestive gland.
C) Tongue, absorption, taste , swallow
Odd word :- Absorption
Remaining are parts of the mouth.
D) oesophagus, small intestine , large intestine, Rectum
Odd word :- small intestine
Digestion occurs in small intestine. In small intestine juices are released for the digestion of food. But in other parts no juice are released or no digestion occurs.
16.) You were blind folded and asked to identify the drinks provided In two different glasses. You could identify drinks A as lime juice and B as bitter gourd juice. How could you do it inspite of being blindfolded?
Answer:- Human beings have different organs for different purposes. Such as we have tongue for taste, and mixing saliva in food. We can identify the things we eat without watching them, our tongue do that work. Because our tongue have different types of taste buds which help to detect the taste . Thus we can identify it blindfolded also.
17.) Fill in the blanks with suitable words:
a) The alimentary canal stretches from ______ to ____.
b) Teeth are rooted in separate _____ in between the ______ .
c) Digestion of food starts in ____ and gets completed in _____.
d) _____ is the largest gland in the human body.
Answer:-
A) The alimentary canal stretches from mouth to anus.
B)Teeth are rooted in separate sockets in between the gums.
C) Digestion of food starts in buccal cavity and gets completed in small intestine.
D) Liver is the largest gland in the human body.
18.) Following statements describe the five steps of animal nutrition. Read each statement and give one word for each statement. Write the terms that describes each process.
Answer:- The terms which describe the process are –
A) Transportation of absorbed food to the different parts of the body and their utilisation.
→Assimilation
B) Breaking of complex food substances into simpler and soluble substances.
→ Digestion
C) Removal of undigested and unabsorbed solid residues of food from the body.
→ Egestion
D) Taking food into the body.
→Ingestion
E) Transport of digested and soluble food from the intestine to blood vessels.
→ Absorption
• Short Answer Questions
19.) Match the animals in Column I with their mode of feeding listed in column II.
Column I |
Column II |
Animals |
Modeoffeeding |
a) House fly |
I)biting and chewing |
b) Cockroach |
II) suckling |
c) Mosquito |
III) sponging |
d) Infants |
IV) sucking |
Answer:-
A) House fly → iii) sponging
B) Cockroach → i) biting and chewing
C) Mosquito → iv) sucking
D) Infants →ii) suckling
20.) Boojho took some grains of boiled rice in the test tube ‘ A’ and Paheli took boiled and chewed rice in the test tube ‘B’ . Both of them poured 1 – 2 drops of iodine solution into the test tube and observed the colour change. What colour change would they have observed? Give reasons for your answer.
Answer:-
The first Test tube ‘A’ in which only boiled rice is there , it contains starch molecules.
The second test tube ‘B’ contains boiled rice which is chewed that means it contains saliva in it.
Saliva helps the starch molecules to break down in simple sugars.
When 1-2 drops of iodine are added in both the test tubes, test tube ‘A’ shows blue black colour due to presence of starch in it, and the test tube ‘B’ will not change any colour. Because chewed rice contains saliva which break down the starch into the simple sugars and thus no starch remains there, only sugar is present. Therefore on addition of iodine it doesn’t change any colour .
21.) ‘A’ got her gall bladder removed surgically as she was diagnosed with stones in her gall bladder. After the surgery, she faced problems in digestion of certain food items when consumed in bulk. Can you tell which kind of food items would they be and why?
Answer:- gall bladder is a sac like organ which stores bile juice. Bile juice helps in the digestion of fatty substances. Fats are large size of globules, which are not soluble in water . Thus they don’t absorbed easily as compared to other nutrients. But bile juice helps to break down the larger sized fat globules into smaller sized particles. Thus the food which is consumed in bulk and faces problem in digestion by ‘A’ would be fat.
22. Match the organs in column I and the words listed in Column II .
Column I |
Column II |
a) Rectum | I) Mucous |
b) Gall bladder | II) Villi |
c) Stomach | III) Taste buds |
d) Tongue | IV) Faeces |
e) Small intestine | V) Bile juice |
Answer:-
A) Rectum → iv) faeces
B) Gallbladder → v) bile juice
C) Stomach → I) mucous
D) Tongue → iii) taste buds
E) Small intestine→ ii) villi
23.) Ruminants such as cows and buffaloes swallow their food hurriedly and then sit restfully and chew their food. Can you reason why ?
Answer:- Ruminants such as cows and buffaloes swallow their food hurriedly these swallowed undigested food is taken in the part of the animals stomach which is known as Rumen. In these rumen these food gets partially digested. These partially digested food in the rumen is called Cud. When the ruminants sit restfully These cud is then returns to the mouth and the cud is then chews by animals. These process of chewing cud is known as Rumination. And the animals which do the process of Rumination are called Ruminants. These animals mainly eat grass which is rich in cellulose. The bacteria present in the rumen helps in the digestion of cellulose of grass.
24.) Boojho and Paheli were eating their food hurriedly so that they could go out and play during the recess. Suddenly boojho stared coughing violently. Think of the reasons why he was coughing and discuss with your friends.
Answer:-When boojho eat food hurriedly , the food particles enters the windpipe which is present on adjacent side of the foodpipe. The Windpipe perform the function of transport the airfrom the nostrils to the lungs. Both are adjacent to each other but Inside the throat Food taken inside andair we breathe share a common passage. During the swallowing process a door like flapor valve closes the passage of the Windpipe and take the food into the food pipe. When we eat hurriedly sometimes, food particles enters the wind pipe and we feel like choked or we get hiccups or cough. And the coughing helps food particles get out of the Windpipe.
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Long Answer Questions
25.) Fill in the blanks using the words listed below.
Water , front , intestinal, salts , pseudopodia, back, vacuole
a) The digestion of all food components us completed by the ______________ juice.
b) Large intestine absorbs __________ and some from the undigested food.
c) Tongue is attached at the ________ to the floor of the mouth cavity and is free at the _____________.
d) Amoeba pushes out _______ around the food and traps it in a food ____________ .
Answer:-
A)the digestion of all food components us completed by the intestinal juice.
B) large intestine absorbs water and some salts from the undigested food.
C) tongue is attached at the back to the floor of the mouth cavity and is free at the front .
D) Amoeba pushes out pseudopodia around the food and traps it in a foodvacuole.
27.) Read the following passage carefully and answer the questions that follows it.
Bile juice is stored in a sac called, gall bladder , located near it’s organ of secretion, liver. The gall bladder releases the bile juice into the small intestine whenever food reaches there . Through bile juice is devoid of any digestive enzymes. It is required for the digestion of fats. The fats cannot be digested easily because they are insoluble in water and are present as large globules. Bile juice breaks down big fat droplets into smaller droplets. These are then easily digested by the enzymes released from the pancreas.
A) Which organ secrets the bile juice ?
Answer:- the organ which secrets the bile juice is called “Liver”.
But the secretd bile juice is stored in the sac called “gall bladder” .
Bile juice is the enzyme which performs the function of break down of large fat globules into smaller .
B) Why is digestion of fats difficult as compared to that of other nutrients ?
Answer:- digestion of fats are difficult because it is not soluble in water , it is insoluble. Fats are present in large size of globules , which is difficult to digest.Fat is digested with the help of bile juice. Bile juice break down the larger fat globules into smaller and thus help in digestion of fat. Other nutrients are present in smaller globular size and are water soluble thus they digested easily as compared to the fats.
C) How does bile juice help in digestion of fat ?
Answer:- digestion of fat is not easy. Because fats are insoluble in water as well as it has large size of globules which are not digested easily. The break down of these large size globules into smaller size is important for its digestion. Thus these process is carried out with the help of bile juice. Bile juice breaks down big fat globules into the smaller sized droplets and thus the digestion of fats get easy.
D) Where is the digestion of fat completed?
Answer:- Digestion of fat is completed in small intestine. In Small intestine the secretion of liver which is bile juice is added which performs the function of break downs of larger fats into smaller fat globules. Thus the digestion of fat is completed in small Intestine.
E) Does bile juice digest fat completely?
Answer:- No. Bile juice cannot digest fat completely. Fat globules are larger in size and they are water insoluble also, thus they couldn’t digested easily. Bile juice helps in break down of fat molecules from larger size to smaller . Later on in small intestine it is digested further.
29.) Open your mouth, look into a mirror and try to count the different type of teeth in your mouth. Compare them with figure. 2.3 on page 13 of your NCERT textbook. Record your observation in the table below.
A) Did you observe any difference in the number of teeth ? If yes, could you identify which type of teeth showed the difference ?
B)compare the number and type of teeth in an adult (say your parents or cousins who have reached the age of 25-30 or more. ) Note your observation.
Answer:-
Type of teeth |
Number of teeth |
|
In my mouth | In the figure | |
Incisors | 4 | 4 |
Canines | 8 | 8 |
Premolar | 8 | 8 |
Molar | 7 | 12 |