NIOS Class 12 Biology Chapter 13 Solution – Nutrition and Digestion
NIOS Class 12 Biology Solution Chapter 13 Nutrition and Digestion . NIOS Class 12 Biology Chapter 13 Question Answers Download PDF. NIOS Class 12 Biology Notes.
Board |
NIOS |
Class |
12th (Higher Secondary) |
Subject |
Biology |
Topic |
Question Answer, Solution, Notes |
INTEXT 13.1
1.) List the five major steps in animal nutrition
(i) .Ingestion
(ii) .Digestion Ingestion
(iii) . Absorption
(iv) Assimilation
(V)Egestion
2.) What is intracellular digestion? Give example of an organism showing intracellular
Digestion
Ans: All the five steps of digestion occur inside the cell itself is called intracellulardigestion . eg. Paramecium, Amoeba etc shows intracellular Digestion
INTEXT 13.2
1.) Match the characteristics in column A with the parts of digestive system given in column B
Column A | Column B |
(1) Common passage for air breathed in and the food swallowed | (d) Pharynx
|
(2) Elastic bag like structure | (f) Stomach
|
(3) Has three limbs-ascending, transverse and descending
|
(g) Colon
|
(4) Longest part of the food canal | (a) Small intestine
|
(5) Receives bile and pancreatic juice | (c) Duodenum |
(6) Narrow worm-shaped projection | (e) Appendix
|
(7) Largest gland in body | (h) Liver
|
(8) Gland located in the bend of | (b) Pancreas
|
2.) Name the three salivary glands and mention their location in the mouth cavity
Ans:The three salivary glands are as follows
Parotid – which is located in front of and below ear
Submaxillary – which is located in inner side of lower jaw.
Sublingual – which is located below the tongue
INTEXT 13.3
1.) How is grinding of food in the mouth helpful in digestion?
Ans: Food is broken into little pieces in mouth using mechanical means such as cutting, grinding, and swallowing before being pushed along the alimentary canal. Smaller particles expose more surface area for action by enzymes . This way the mouth helpful in digestion
2.) Name the source gland for following enzymes.
(i) amylase – Salivary glands
(ii) pepsin – Stomach
(iii) lipase ..- Pancreas.
3.) List at least four enzymes that contribute towards digesting proteins.
(i)Pepsin (ii) Trypsin (iii) Chymotrypsin, . (iii) Carboxypeptidase.
INTEXT 13.4
1.) In which part of the alimentary canal does maximum absorption of water occur?
Ans: colon absorbs the maximum water .Diffusion occurs in the colon, where the majority of the water in food is absorbed. The colon utilises active transport to take in some mineral ions.
2.) List any three ways in which the intestine increases the surface area for absorption?
(i) It is very long and therefore provides more surface area for absorption
(ii) Single cell eptithelial lining further reduces the distance between the food and underlying blood vessels
(iii) The epithelial cells have microvilli which are projections of plasma membrane to further increase the absorptive surface
3.) Which end products of digestion are absorbed by
(i) blood capillaries of intestinal villi – Amino acids and simple sugars
(ii) Lacteals – fatty acids and glycerol.
INTEXT 13.5
1.) Mention the source of secretion and the effect of the following:
(i) Gastrin- is secreted in stomach which stimulates secretion of gastric juice
(ii) Enterogastrone-Duodenum, it stops secretion of gastric juice.
INTEXT 13.6
1.) Name any three substances related to the blood, produced by liver.
(i) Fibrinogen, (ii) prothrombin (iii) heparin
2.) List any three substances which the liver stores.
(i) Sugar (ii) Iron (iii) Vitamin A
3.) What happens to excess amino acids absorbed from gut ?
Ans: Protein digestion produces amino acids as a byproduct. Excess amino acids are converted by the liver to urea and sugar. Sugar is stored for utilisation and eliminated in urine in conjunction with urea.
INTEXT 13.7
1.) (a) A doctor advises a person to sip ORS at regular intervals because he/she was suffering from diarrheoa. What is this ORS?
Ans: Oral Rehydration Solution which is drinking water containing a pinch of sugar and salt. Person who is vomiting should sip this fluid at regular intervals. ORS prevents dehydration in the body.
(b) Name any one causative agent of diarrhoea in developing countires.
. Ans: Passing loose stool or liquid stool three or more times in a day is termed Diarrhoea. Rota virus and E.coli are the causative agent of diarrhoea in developing countires.
(c) During the rainy season there is a rise in diarrhoea cases. What piece of advice will you give to your younger brother/sister to prevent oneself from getting diarrhoea?
Ans: Wash hands with soap and water before eating the meal ,wash raw vegetables well before cooking or consuming and cover food so that flies cannot sit on it .
2.) A little girl/boy had a problem in passing stool. The faeces were dry and hard. The doctor said that this was because the child was not taking adequate amount of fibres in the diet and was not taking proper diet at proper time. What is this child suffering from?
. Ans: The child is suffering from constipation.
3.) What is dyspepsia? What are its symptoms?
. Ans: Indigestion is a feeling of discomfort in the upper abdomen during or immediately after eating (commonly called stomach ache). There is a recurrent pain and burning sensation in the upper abdomen. Indigestion may be triggered by overeating, eating spicy, greasy or fatty foods, emotional stress, consuming too much of high fibre foods
4.) Which organ of the body is involved in jaundice and how can you make out that a person is suffering from jaundice.
Ans: In jaundice, there is a yellow discoloration of the skin and the eyes due to a high level of bilirubin (bile pigment) in the blood.
TERMINAL EXERCISE
1.) Explain the term “autotrophs”. How are animals different from plants with regard to their mode of nutrition?
Ans: Autotrophs are the organism which make their own food for nutrients.
Green plants produce by inorganic material by co2 and h2o while animal rely on another animal and plants.
2.) Enlist at least ten organs of the alimentary canal of man.
Ans: Mouth , pharynx, oesophagus, stomach, small intestine , colon, jejunum, duodenum, large intestine.
3.) Define the term “digestion”. List the digestive processes occurring in the small intestine.
Ans: Digestion is the process by which complex dietary components are converted by enzymes into more easily absorbed and utilised forms for the body’s cells. Three main digestive juices act on the food that has been partially digested in the stomach and is known as chyme in the small intestine.
(i) Bile from the liver; (ii) Pancreatic juice from the pancreas; and (iii) Intestinal juice,
The bile and pancreatic channels of each organ combine to form the common hepato pancreatic duct, which empties into the duodenum. The food directly combines with the intestinal juice.
4.) How does digestion of carbohydrates and proteins take place in humans?
Ans: Proteins and carbohydrates are digested in intestine, Proteins are broken down into amino acids, and carbohydrates into glucose.
5.) Explain the role of the following in the digestive process in humans :
(a) Gastrin : It secrete gastiric juice in stomach
(b) Hydrochloric acid : destroys bacteria that come into contact with food, and loosens food’s fibrous substance,
(c) Secretin : stimulates the flow of pancreatic juice, which is rich in bicarbonates
- ) Write short notes on
(a) absorption of the digested food : The small intestine is where most of the digested food is absorbed; simple sugars and amino acids go into the blood capillaries of the intestinal villi, while fatty acids and glycerol go into lacteals.
(b) assimilation : Utilization of food by the cells is called assimilation. The body assimilates the digested food in the following ways after taking it in through the food canal.
(i) Glycerol and fatty acids are once more transformed into fats, which can either be utilised or stored in adipose tissue.
(ii) Excessive simple sugars (monosaccharides) are transformed in the liver into complex polysaccharides like glycogen.
(c) defaecation : Plant fibres that haven’t been digested and partially digested chemicals that haven’t been absorbed enter the rectum. Such meal leftovers are short-term preserved in the rectum. As more water is absorbed, the leftovers solidify to create excrement, this process is called defaecation.
(d) role of liver in metabolism : controlling blood sugar levels by holding extra glucose that is absorbed from the intestines after food digestion, Breaking down of excess amino acids.
7.) Name the enzymes concerned with the digestion of various carbohydrates, the region of the gut where they act and their products in the table given below:
Carbohydrate | Enzyme | Region of gut | Product |
Starch | Salivary amylase | Mouth | Converts starch into maltose |
Dextrin | dextrinase | Small intestine | Converts starch into glucose |
Maltose | Maltase | Small intestine | Converts maltose into glucose |
Sucrose | sucrase | Small intestine | Converts starch into Glucose |
Lactose | Lactase | Small intestine | Converts lactose into glucose and galactose |
8). Bile has no digestive enzyme yet it plays a key role in digestion. What is its role?
Ans: Bile is a yellowish, green, alkaline liquid. Large amounts of sodium carbonate, which make chyme (semi-digested food) alkaline by neutralising its acid, are consumed.
9.) Draw a well labelled diagram of alimentary canal in humans.
Alimentary canal
10.) List common digestive disorders. Add a note on ORS.
Ans: Vomiting , diarrhea, constipation, indigestion, jaundice etc
Oral Rehydration Solution which is drinking water containing a pinch of sugar and salt. Person who is vomiting should sip this fluid at regular intervals. ORS prevents dehydration in the body.