Digestion & Absorption: Important Questions

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Very Short Answers [1 Mark]

Ques. What are the secretions found both in Goblet cells and Parietal cells?

Ans. The Goblet cells secrete mucus and the Parietal cells secrete hydrochloric acid and intrinsic factors.
 

Ques. Why does pepsinogen become active in the stomach?

Ans. Pepsinogen becomes active in the stomach due to the presence of HCI.
 

Ques. What is pancreatic amylase?

Ans. The pancreatic juice contains a starch-digesting enzyme called pancreatic amylase.
 

Ques. Show and label the three segments of the human small intestine.

Ans. The three parts of the small intestine of man are Duodenum, Jejunum, and Ileum.

Small Intestine

Ques. Which is the largest gland in our body?

Ans. The largest gland in the human body is the Liver.
 

Ques. What is atheroma?

Ans. The deposition of cholesterol on the walls of arteries is called atheroma.
 

Ques. Describe egestion.

Ans. The undigested food that is excreted from the body is called egestion.
 

Ques. Name the hardest substance in the body.

Ans. The hardest substance in the body is the enamel.
 

Ques. List the enzymes that are involved in the breakdown of nucleotides into bases and sugars.

Ans. Nucleotidases and nucleosidases.

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Short Answer Questions [2 Marks Questions]
 

Ques. What is the Pancreas?

Ans. The Pancreas is an abdominal organ located behind the abdomen in the stomach and surrounded by the spleen, liver and small intestine. It is one of the most vital parts of the human digestive system and is responsible for regulating blood sugar levels in the body.

Read More: Symptoms of Liver Problems

Ques. What is the liver?

Ans. Positioned in the right upper quadrant of the abdomen but below the diaphragm, the liver is known to be the largest human organ that plays a pivotal role in the digestion of fats, metabolism of carbohydrates and secretion of bile.

Liver

Ques. What do you mean by incomplete and complete types of digestive tracts?

Ans. The incomplete type of digestive tract has only one opening for food intake and elimination of indigestible matter e.g. coelenterates planaria, liver fluke etc. The complete type of digestive tract has a separate opening for food intake and elimination of indigestible matter e.g. humans, frog, rabbit, etc.
 

Ques. What are wisdom teeth? Illustrate the human dental formula.

Ans. The last molar grown in both the upper and lower jaws on both sides at the age of maturity are called wisdom teeth. The human dental formula can be illustrated as, 1 ²/2, C¹/1 Pm²/2, M³/3.

Ques. What is the passive absorption of food?

Ans. The absorption of nutrients from a higher concentration to a lower concentration without the expenditure of energy is called passive absorption of food. The nutrients in the intestinal lumen are in a higher concentration. The diffusion of molecules would continue so long as the difference in concentration persists. The process of diffusion is slow. The solute concentration is higher in the blood than in the intestinal content when water is absorbed by osmosis from the interstitial lumen to the intestinal cells and then to the blood.

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Long Answers [3 Marks]

Ques. Define chemotrophs and heterotrophs?

Ans. Organisms that capture the energy released during oxidation of inorganic chemical substances and prepare organic food with its help such as nitrifying bacteria e.g. Nitrosomonas and nitrobacteria, are called chemotrophs. On the other hand, organisms that cannot utilize sun energy but use chemical bond energy in the form of organic molecules or food synthesized by other organisms to build up their organic molecules such as animals, fungi, some protestants, (Trypanosoma) and any kind of bacteria are called heterotrophs.
 

Ques. What are digestion, mechanical digestion and chemical digestion?

Ans. The process of converting large insoluble food into tiny, soluble and absorbable forms is known as digestion. The complete process of digestion occurs consecutively by the union of both methods:

1. Mechanical digestion: When food is completely broken down into smaller, soluble fragments physically, the process is called mechanical digestion. This process begins from the mouth to the stomach through the act of chewing (mouth), churning (stomach) and segmentation (small intestine).
2. Chemical digestion: When food is completely broken down by chemical agents such as acids, bile and other enzymes, the process is known as chemical digestion.

Ques. What is the role of micelles in fat absorption?

Ans. During digestion, the fat present in the colon transforms into water-insoluble monoglycerides, diglycerides and fatty acids. Since they are insoluble in water, they cannot be absorbed directly from the intestine. Bile salts convert them into small, spherical, and water-soluble droplets called micelles and as such, fatty acids, glycosides, sterols and other fat-soluble vitamins are absorbed into the intestinal cells through the micelles.

Also Check: Human Insulin

Ques. Give two functions of trypsin?

Ans. Trypsin is known to convert chymotrypsinogen into chymotrypsin.
Pepsinogen HCL> Pepsin (active)

Trypsin also degrades proteases and peptones, further converting them to peptides.
Trypsin + Peptones + Protcoses Peptides

Ques. Express briefly how the DNA content in the food digested.

Ans. The DNA content is broken down by the enzymes in pancreatic juice and succus entericus in the intestine region of our alimentary canal.
DNA content Deoxyribonucleate Enzyme → Deoxyribonucleotides
Deoxyribonucleotides = PO4 + Deoxyribonucleotides
Deoxyribonucleotides Nucleosidase Enzyme → Deoxyribose + Purine +Pyrimidine

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Very Long Answers [5 Marks]

Ques. Write the changes occurring in the passage through the alimentary canal when a person has ingested roti and dal as part of their meal.

Ans. The following are the changes:

1. The teeth in the mouth chew the food substances, wherein the carbs present in the food are digested through the action of the enzyme secreted by the salivary gland – the salivary amylase.
2. During this stage of the process, the food is only partly digested and reaches the stomach. Here it is treated with acidic HCl. The proteins in the food are digested through proteolytic enzymes.
3. The gallbladder secretes bile to digest the lipids present in the food.
4. The semi-digested food is finally digested in the duodenum of the small intestine by the action of digestive enzymes (pancreatic and intestinal juices).
5. After the process of digestion, the small intestine begins absorbing the disintegrated food in the form of glycerol, amino acids, starch, etc.
6. The undigested food is finally eliminated from the system through the anus.

Ques. Write the mechanism of absorption.

Ans. The mechanism of absorption is a phenomenon through which the end products of digestion pass via the intestinal mucosa into the lymph or blood, which is then carried out through the means of active, passive or facilitated transport. With the help of processes like simple diffusion, minute quantities of monosaccharides, e.g., amino acids, glucose and a few electrolytes (chloride ions) are absorbed. The passage of these substances into the blood is decided by the concentration gradients.
However, amino acids and glucose are absorbed with the help of carrier proteins referred to as facilitated transport. Water transport is dependent on the osmotic gradient. Energy is required for active transport as it takes place against the concentration gradient. Through this mechanism, several monosaccharides such as glucose, nutrients such as amino acids, electrolytes such as Na+ get absorbed into the blood.

Ques. Where does the digestion of starch, proteins and fats take place and what is the role played by the associated glands?

Ans. Starch - Digestion of starch takes place in the mouth where the carbohydrates present in the food are broken down or digested to form sugar. The saliva secretes an enzyme called salivary amylase that helps in the digestion of starch into sugar.

Proteins - The gastric glands present in the stomach secrete gastric juice containing (HCI) hydrochloric acid and enzymes like pepsin which helps in breaking down the proteins into smaller fragments called peptones.

Fat - Fat is digested in the duodenum (small intestine) with the help of the bile juice secreted by the liver and stored in the gallbladder. The pancreas secretes trypsin, amylase and lipase which are then poured into the duodenum.

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