Class 7 Science Chapter 2 HOTS Questions - Nutrition in Animals

Q1: The long structure of small intestine is accommodated in small space within our body. Comment.

Ans: The small intestine is about 7.5 metre long It is accommodated in a coiled form inside our body.

Q2: Cellulose rich food substances are good source of roughage in human beings. Justify.

Ans: Cellulose rich food substances are good source of roughage in human beings. It is because the cellulose digesting bacteria are not present in the body of human beings due to which human beings cannot digest cellulose (present in plant foods).

Q3: You were blindfolded and asked to identify the drinks provided in two different glasses. You could identify drink A as lime juice and B as bitter gourd juice. How could you do it inspite of being blindfolded?
Ans: Inspite of being blindfolded, one could identify two different drinks with the help of taste buds present in the tongue.

Q4: ‘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?
Ans: After surgical removal of gall bladder, ‘A’ would face problems in digestion of fat and fatty substances when consumed in bulk. This is because the bile juice stored in the gall bladder helps in digestion of fats.

Q5: Boojho took some grains of boiled rice in test tube ‘A’ and Paheli took boiled and chewed rice in test tube ‘S’. 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.
Ans: In test tube A, blue black colour appeared because of presence of starch. In test tube 6, colour of iodine will not change because of digestion of starch into sugars by the action of saliva in our mouth.

Q6: Boojho and Paheli were eating their food hurriedly so that they could go out and play during the recess. Suddenly, Boojho started coughing violently. Think of the reasons, why he was coughing and discuss with your friends?
Ans: Sometimes when we eat hurriedly, talks or laughs while eating, the flap-like valve (called epiglottis) which closes the passage of windpipe remains open. Therefore, the food may enter into the windpipe. Coughing helps to clear the passage and returns the food particle back to the foodpipe.

Q7: Ruminants such as cows and buffaloes swallow their food hurriedly and then sit restfully and chew their food. Give reason.
Ans: Ruminants such as cows and buffaloes swallow their food hurriedly and store it in a part of the stomach called rumen. The cellulose of the food is digested here by the action of certain bacteria which are not present in humans. Later, this partially digested food is returned to the buccal cavity of the animals in small lumps and animal chews it to complete the process of digestion. This process is called rumination.

Q8: Name the secretions of stomach which digest food.

Ans: The inner lining of stomach secretes mucous hydrochloric acid and digestive juices.

Q9: Name the parts of the alimentary canal where
(a) water gets absorbed from undigested food
(b) digested food gets absorbed
(c) taste of the food is perceived
(d) bile juice is produced
Ans:
(a) large intestine
(b) small intestine
(c) tongue
(d) liver

Q10: 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
Ans:
(a) Starch, because rest all are glands and starch is a type of carbohydrate.
(b) Stomach, because rest all are digestive glands and stomach is a digestive organ.
(c) Tongue, because rest all are digestive processes and tongue is a part of digestive system.
(d) Small intestine, because it carriers the process of digestion and rest are not involved in digestion.

Q11: Following statements describe the five steps in animal nutrition. Read each statement and give one word for each statement. Write the terms that describe each process.
(a) Transportation of absorbed food to different parts of body and their utilisation.
(b) Breaking of complex food substances into simpler and soluble substances.
(c) Removal of undigested and unabsorbed solid residues of food from the body.
(d) Taking food into the body.
(e) Transport of digested and soluble food from the intestine to blood vessels.
Ans:
(a) Assimilation
(b) Digestion
(c) Egestion
(d) Ingestion
(e) Absorption

Q12: Briefly describe the process of digestion in Amoeba with the help of labelled diagram.
Ans: Feeding and Digestion in Amoeba
Amoeba is a microscopic single celled organism, which is found in pond water. It is a very simple animal and cannot be seen by naked eyes. Amoeba has a cell membrane, a rounded dense nucleus and many small bubble-like vacuoles in its cytoplasm. These vacuoles are of two types, i.e. food vacuole and contractile vacuole. Food vacuole contains food surrounded by water while contractile vacuole contains liquid or water and controls water regulation activity in Amoeba. Its shape is not fixed, i.e. it constantly changes its shape and position. The body of Amoeba has finger-like projections, called pseudopodia or false feet. It captures food and helps in locomotion of Amoeba.

The food of Amoeba are microscopic organisms like tiny plants and animals present in pond water. When Amoeba senses its food, it pushes out pseudopodia around the food particle and engulfs it. The two pseudopodia join around the food particle and trap the food particle with a little water forming vacuole around food, thus the food gets trapped. Digestive juices present inside the vacuole, acts on the food and break it into simpler substances. This digested food is then absorbed and is used for growth, maintenance and multiplication of Amoeba. The undigested food residue is expelled outside by the vacuole. The basic process of digestion of food and release of energy is as similar to the other organisms.

Q13: Read the following passage carefully and answer the questions that follow it.
Bile juice is stored in a sac called, gall bladder, located near its organ of secretion, liver. The gall bladder releases the bile juice into the small intestine whenever food reaches there. Though 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 secretes the bile juice?
(b) Why is digestion of fats difficult as compared to that of other nutrients?
(c) How does bile juice help in digestion of that of other nutrients?
(d) Where is the digestion of fat completed?
(e) Does bile juice digest fat completely?
Ans:
(a) Bile juice is secreted by liver.
(b) Digestion of fats is difficult as compared to that of other nutrients because of insolubility of fat in water.
(c) Bile juice helps in digestion of fat by breaking down big fat droplets into smaller droplet.
(d) Digestion of fat is completed in small intestine.
(e) No, fat is not completely digested by bile juice.

Q14: Discuss the various associated glands of digestive system and their role in digestion.

Ans: The various associated glands of digestive system and their role in digestion are as follows

• Salivary gland digestion of starch in mouth.
• Liver secretes bile juices which help in the digestion of fats.
• Pancreas secretes pancreatic juices which act on carbohydrate, fats and proteins and change them into simpler compounds.

Q15: Windpipe runs adjacent to the foodpipe. What will happen if food particles enter the windpipe? Explain.

Ans: The windpipe carries air from the nostrils to the lungs. It runs adjacent to the foodpipe. If, by chance, food particles enter the windpipe, we feel choked, get hiccups or cough.

Q16: Can we survive only on raw, leafy vegetables/grass? Discuss.

Ans: No, human beings cannot survive only on raw, leafy vegetables or grass for the following reasons:

• Human beings require all essential nutrients like carbohydrates, proteins, lipids, vitamins and minerals for survival.
• Raw, leafy vegetables or grass do not provide the required nutrients to the body, leading to less immunity and risk of catching diseases.
• Sometimes, raw vegetables contain harmful germs and viruses, making them unfit to consume.

Q17: Differentiate between assimilation and egestion. 

Ans: Absorbed digested food materials are transported via the blood vessels to different organs of the body where they are used to build complex substances such as the proteins required by the body. This process is called assimilation but the process of removal of waste faecal matter through the anus from time-to-time is called egestion.

Q18: What role does villi performs in the small intestine?

Ans: The villi increase the surface area for absorption of the digested food. The surface of the villi absorbs the digested food materials and passes them into blood. The absorbed substances are transported via the blood vessels to different organs of the body.