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Absorption - class-XI

Description: absorption
Number of Questions: 45
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Tags: digestion and absorption digestive system of human digestion food through digestive tract human physiology bio-chemistry biology
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Food  is largely absorbed in 

  1. Stomach

  2. Oesophagus

  3. Small intestine

  4. Colon


Correct Option: A
Explanation:
Stomach - It is a hotbed of digestive activity, but virtually nothing (except alcohol) is absorbed there. 
Oesophagus - Nothing is absorbed in the oesophagus.  The esophagus is a tube that connects the throat and the stomach. If the mouth is the gateway to the body, then the esophagus is a highway for food and drink to travel along to make it to the stomach. 

Small Intestine - It is the site of virtually all nutrient absorption, including proteins, carbohydrates, fats and water, as well as vitamins and minerals.

Colon - It extracts water and salt from solid wastes before they are eliminated from the body and is the site in which flora-aided (largely bacterial) fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a major role in absorption of foods and nutrients.
So. the correct option is 'Stomach'.

Which of the following is the most rapidly transported monosaccharide into the bloodstream from the intestine?

  1. Mannose

  2. Glucose

  3. Galactose

  4. Fructose


Correct Option: C
Explanation:

Transportation of galactose is most rapid as it attaches with sodium ion and easily dragged by the protein carries so it is very easy to transport it while glucose and fructose require energy to transport as they are transported by active transport.

So the correct option is 'Galactose'.

Which of the following electrolyte pumps helps in active absorption of glucose in the intestinal walls?

  1. Sodium

  2. Potassium

  3. Chloride

  4. Bicarbonate


Correct Option: A
Explanation:

Active absorption occurs against the concentration gradient which requires energy. $Na^+$ which transports by facilitated transport that means it is taken by a protein carrier which has a peculiarity. It drags glucose with sodium ion from the lumen of the intestine to blood and helps in its absorption.

So the correct option is 'Sodium'.

In which of the following parts of the alimentary canal does absorption of nutrients and drugs takes place?

  1. Mouth

  2. Stomach

  3. Small intestine

  4. All of the above


Correct Option: D
Explanation:

Absorption of nutrients and drugs is mainly carried out by the small intestine but the stomach also absorbs certain drugs, water, and alcohol while mouth absorbs a very little amount of water and drugs and breaks down starch.

So the correct option is 'All of the above'.

State which of the following statement is true OR false.
(A) No absorption of food takes place in mouth and oesophagus.
(B) Absorption of glucose depends on sodium ion.
(C) Whole protein particles can be engulfed by pinocytosis.

  1. B and C are true, A false

  2. All are true

  3. A and C are true, B is false

  4. A and B true, C false


Correct Option: D
Explanation:

  • After food is being swallowed, from the mouth it is transported to the stomach. No absorption of nutrients takes place in the mouth and oesophagus. Hence, No absorption of food takes place in the mouth and oesophagus.
  • Active glucose absorption is thought to depend on a gradient of sodium ion concentration across the brush border membrane of intestinal epithelial cells. Specifically, glucose absorption was minimally reduced when intraluminal sodium concentration was reduced. Hence, Absorption of glucose depends on sodium ion.
  • Pinocytosis is the absorption of liquids, whereas phagocytosis is the absorption of solid objects which are essentially food for the cell. Phagocytosis engulfs whole particles, which are later broken down by enzymes, such as cathepsins, and absorbed into the cells. Hence, Whole protein particles cannot be engulfed by pinocytosis.
So, the correct answer is 'A and B true, C false'.

What is correct about microvilli?

  1. Also known as brush bordered epithelia

  2. Found in small intestine and PCT both

  3. Increase absorption of food

  4. These are infoldings of cell membrane


Correct Option: C
Explanation:
  1. Brush bordered epithelium is microvilli covered Epithelial surface found in the body.
    2. The columnar and cuboidal epithelium of small intestine and PCT have the surface covered with microvilli for increasing absorption.
    3. Cilia are meant for the movement of fluid while microvilli function to increase the absorption and secretion.
    4. Microvilli are microscopic cellular membrane protrusions that increase the surface area for diffusion and are involved in a wide variety of functions, including absorption, secretion, cellular adhesion, and mechanotransduction.
    So, the correct option is 'Increase absorption of food.

In which part of gastro-intestinal tract does maximum absorption of water occur?

  1. Colon

  2. Duodenum

  3. Jujenum

  4. Ileum


Correct Option: A
Explanation:

Maximum absorption of water occurs in the large intestine, that is, in the colon. Certain drugs and metals are also absorbed here. 

So, the correct answer is 'Colon'. 

Choose the correct answers from the alternatives given.
The villi present on the wall of the small intestine

  1. secrete digestive enzymes

  2. increase the surface area for absorption

  3. hold mucus, so ulcers do not form

  4. hold products of digestion, so they do not enter the large intestine


Correct Option: B
Explanation:

 The absorption of digested carbohydrates, proteins and fats  is done in the small intestine with the help of villi which helps increase the surface area of the intestine. Villi are finger like projections on the intestinal wall that absorbs digested food material. Carbohydrates and proteins are absorbed into blood, while fats are absorbed into the lymph

So, the correct answer is 'increase the surface area for absorption'

Which one of the following is a non-pathogenic bacteria of human intestines?

  1. Mycobacterium sp.

  2. Escherichia coli

  3. Entamoeba coli

  4. Balantidium coli


Correct Option: B
Explanation:

E.coli strains are normally present in the large intestines where they help in the production of Cyanocobalamin (Vitamin B12).

Movement of alimentary canal does not help in slipping down of food is

  1. Peristalsis movement

  2. Pendular (segmentary) movement

  3. Both

  4. None


Correct Option: B
Explanation:

Certain muscular contraction of alimentary canal such as segmentary/pendular are responsible for churning and mixing of the food thoroughly with digestive juices not for propel.

Which of the following organs absorbs food nutrients through villi?

  1. Small intestine

  2. Oesophagus

  3. Rectum

  4. Stomach


Correct Option: A
Explanation:

The absorption is done in the small intestine with the help of villi which helps increase the surface area of the intestine, so as to store more digested food.

So, the correct option is 'small intestine'.

Read the following statements and select the correct option.
Statement 1 : The human small intestine is the longest portion in the alimentary canal.
Statement 2 : Absorption of digested food requires a very large surface area. 

  1. Both statements 1 and 2 are correct.

  2. Statement 1 is correct but statement 2 is incorrect.

  3. Statement 1 is incorrect but Statement 2 is correct.

  4. Both statements 1 and 2 are incorrect.


Correct Option: A
Explanation:

The correct answer is (a).

We eat food, which is composed of all the nutrients like carbohydrates, proteins, fats, vitamins, minerals and water. After digestion, these are absorbed in the form of glucose, amino acids, fatty acids, glycerol etc. What mechanisms are involved in absorption of digested food and water?

  1. Diffusion and osmosis respectively

  2. Osmosis and diffusion respectively

  3. Reverse osmosis and facilitated diffusion respectively

  4. None of the above


Correct Option: A
Explanation:

Diffusion is a process in which the molecules intermingle due to their kinetic energy and movement of molecules is from higher concentration to lower concentration. Osmosis is a process in which the water molecules move from lower solute concentration to higher solute concentration through a semi-permeable membrane. Digested food can pass into the blood vessels in the wall of the small intestine through the process of diffusion and water present in the ingested food is absorbed by the process of osmosis. 

Part of alimentary canal meant for reabsorption of water from chyle is

  1. Small intestine

  2. Colon

  3. Large intestine

  4. Rectum


Correct Option: A
Explanation:

The small intestine is meant for the reabsorption of water. Major absorption of water takes place in the intestine and further in the large intestine.

So, the correct option is 'small intestine'.

A specialized structure in intestine that helps in absorption is

  1. Alveoli

  2. Villi

  3. Bowman's capsule

  4. Salivary glands

  5. Pyloric sphincter


Correct Option: B
Explanation:
  1. The innermost layer lining the lumen of the alimentary canal is the mucosa.
  2. This layer forms irregular folds (rugae) in the stomach and small finger-like foldings called villi in the small intestine.
  3. The cells lining the villi produce numerous microscopic projections called microvilli giving a brush border appearance found on the apical surface of some epithelial cells. 
  4. These modifications increase the surface area enormously and help in secretion and absorptionHence, the specialized structure in the intestine that helps in absorption is villi.
So, the correct answer is 'villi'.

Which of the following substance requires castle's intrinsic factor secreted by stomach for absorbtion in the small intestine?

  1. Aminoacids

  2. Water

  3. Vitamin $C$

  4. Vitamin $B _{12}$


Correct Option: D
Explanation:

Intrinsic factors which are released by the stomach are used in the ileum of the small intestine for the absorption of vitamin $B _{12}$. These are majorly made up of glycoproteins.

So the correct option is 'Vitamin $B _{12}$'

Calcium absorption is always enhanced by the action of the following vitamin

  1. Vitamin A

  2. Vitamin B

  3. Vitamin D

  4. Vitamin K


Correct Option: C
Explanation:

Vitamin D helps in the absorption of calcium ion from the walls of the duodenum to the bloodstream and also maintains its level in the body.

So the correct option is 'Vitamin D'.

Which of the following is true regarding the absorption mechanism of carbohydrates in the intestine?

  1. Glucose is absorbed passively

  2. Galactose is absorbed passively

  3. Fructose is transported actively

  4. Glucose and galactose are transported actively


Correct Option: D
Explanation:

Glucose and galactose transport against the concentration and hence require energy and carrier which transport them from lumen of the intestine to cell and are co transported with sodium ion.

So the correct option is 'Glucose and galactose are transported actively'

What percentage of amino acids is absorbed in the small intestine?

  1. 15%

  2. 30%

  3. 100%

  4. 90-95%


Correct Option: D
Explanation:

Initiation of protein digestion starts in the stomach by pepsin but around 90-95% of protein is digested and absorbed in duodenum and jejunum of the small intestine in the form of amino acids by the action of enzymes trypsin, chymotrypsin and carboxypeptidases.

So the correct option is '90-95%'

Which of the following substances are not absorbed into the lymphatic system?

  1. Fatty acids

  2. Glycerol

  3. Fat soluble vitamins

  4. Water soluble vitamins


Correct Option: D
Explanation:

Water-soluble vitamins are directly absorbed into the intestine and transported to water as they do not require any emulsification because water is free to move in and out but fat soluble liquids absorb into lymph due to their insolubility in water and they need to emulsify before absorption.

So the correct option is 'Water-soluble vitamins'

Which one of the following is not a step during digestion process?

  1. Ingestion

  2. Digestion

  3. Acid processing

  4. Absorption

  5. Elimination


Correct Option: C
Explanation:
  • The chemical breakdown of complex biological molecules into their component parts like lipids into fatty acids, proteins to individual amino acids, carbohydrates into simple sugars.
  • Digestion includes 5 phases :
  1. Ingestion.
  2. Movement.
  3.  Digestion.
  4.  Absorption. 
  5. Further digestion. Hence, the following step not involved during the digestion process is acid processing.
So, the correct answer is 'acid processing'.

Absorption is defined as

  1. elimination of solid waste from the digestive system

  2. breakdown of foods by enzymatic action

  3. passage of nutrients from the gastrointestinal tract into the blood stream

  4. mechanical breakdown of fat


Correct Option: C
Explanation:

  • Absorption is the process by which the products of digestion are absorbed by the blood to be supplied to the rest of the body. 
  • During absorption, the digested products are transported into the blood or lymph through the mucous membrane. Hence, Absorption is defined as the passage of nutrients from the gastrointestinal tract into the bloodstream.
So, the correct answer is 'passage of nutrients from the gastrointestinal tract into the bloodstream'.

Most of the absorption of the products of digestion takes place in humans across the

  1. smooth wall of the large intestine

  2. fingerlike villi of the small intestine

  3. convoluted walls of the stomach

  4. squamous epithelium of the oesophagus


Correct Option: B
Explanation:
  • The innermost layer lining the lumen of the alimentary canal is the mucosa. This layer forms irregular folds (rugae) in the stomach and small finger-like foldings called villi in the small intestine. 
  • The cells lining the villi produce numerous microscopic projections called microvilli giving a brush border appearance. These modifications increase the surface area enormously. 
  • Villi are supplied with a network of capillaries and a large lymph vessel called the lacteal. Hence, Most of the absorption of the products of digestion takes place in humans across the fingerlike villi of the small intestine
So, the correct answer is 'fingerlike villi of the small intestine'.

$30\%$ starch is hydrolysed in Buccal cavity by which of the following enzymes?

  1. Pancreatic $\alpha$ -amylase

  2. Lipase

  3. Maltase

  4. Salivary amylase


Correct Option: D
Explanation:

Salivary glands in your mouth (Buccal cavity) make salivary amylase, which begins the digestive process by breaking down starch when you chew your food, converting it into maltose, a smaller carbohydrate.

So the correct option is D, salivary amylase.

Which of the following stimulates the secretion of gastric juice?

  1. Gastrin

  2. Enterogastrone

  3. Secretin

  4. Hepatocrinin


Correct Option: A
Explanation:

Gastrin is a peptide hormone, that stimulates secretion of gastric acid ($HCl$) by the parietal cells of the stomach and aids in gastric motility. It is released by G cells in the pyloric antrum of the stomach, duodenum and the pancreas.

The gastrointestinal hormone, which stimulates insulin secretion is 

  1. Gastrin

  2. CCK

  3. Secretin

  4. GIP


Correct Option: D
Explanation:

Gastric inhibitory polypeptide (GIP), also known as the glucose-dependent insulinotropic peptide. The function of GIP is to induce insulin secretion, which is stimulated primarily by hyper osmolarity of glucose in the duodenum.

Secretion of gastric juice is controlled by

  1. Gastrin

  2. Cholecystokinin

  3. Enterogastrone

  4. None of the above


Correct Option: A
Explanation:

As food enters the confined space of the stomach, it starts applying pressure to the stomach wall distending it a bit. This distention causes the stomach to release gastrin, which stimulates the gastric glands to secrete more gastric juice.

Gastric juice is secreted under the influence of hormone

  1. Renin

  2. Enterogastrone

  3. Enterocrinin

  4. Gastrin


Correct Option: D

Entry of food in stomach mechanically stimulates it to produce a hormone named

  1. Progesterone

  2. Secretin

  3. Gastrin

  4. Pancreozymin


Correct Option: C

Cardiac sphincter protects back flow of

  1. Food into oesophagus

  2. Blood into heart

  3. Blood into auricle

  4. Blood into venae cavae


Correct Option: A

Which one provides sliminess to food?

  1. Brunners glands

  2. Goblet cells

  3. Both A and B

  4. Peptic cells


Correct Option: C

In jejunum, enzyme required for digestion of amino acid containing compounds is

  1. Trypsin

  2. Pepsin

  3. Peptidase

  4. Chymotrypsin


Correct Option: C

Which one is a gastrointestinal hormone

  1. Prolactin

  2. GH

  3. Enterokinase

  4. FSH


Correct Option: C

Digestion of carbohydrates occurs in

  1. Buccal cavity

  2. Stomach

  3. Intestine

  4. All the above


Correct Option: D

Which is true about digestion and absorption of food?

  1. 60% starch is hydrolysed by salivary amylase

  2. Oxyntic cells secrete pepsinogen

  3. Chylomicrons are small lipoprotein particles passed in intestine into blood capillaries

  4. Fructose and amino acids area absorbed in intestine with the help of carrier ions of $Na^+$


Correct Option: D

Absorption of glycerol, fatty acids and monoglycerides takes place by

  1. Lymph vessels within villi

  2. Walls of stomach

  3. Colon

  4. Capillaries within villi


Correct Option: A

Gastrin is

  1. Hormone

  2. Enzyme

  3. Nutrient

  4. Digestive secretion


Correct Option: A

Which enzymes are likely to act on the baked potatoes eaten by a man, starting from mouth and as it moves down the alimentary canal

  1. Disaccharidase like maltase lipases nucleases

  2. Salivary amylase pancreatic amylase disaccharidases

  3. Salivary maltase carboxypeptidase trypsinogen

  4. Pancreatic amylase salivary amylase lipases


Correct Option: B

Germs entering the body along with food are killed in alimentary canal where pH is

  1. 10

  2. 7

  3. 3

  4. 11


Correct Option: C

Choose the correct answer from the allternatives given.
What is the name of the portion of alimentary canal which crushes the food ?

  1. Crop

  2. Gizzard

  3. Oesophagus

  4. Stomach


Correct Option: B
Explanation:

Answer B: Gizzard

Stomach constructed of thick muscular walls is used for grinding up food, often aided by particles of stone or grit. In certain insects, the gizzard features chitinous plates or teeth.

Secretin is gastrointestinal tract hormone that

  1. Acts on exocrine part of pancreas and stimulates the secretion of water and bicarbonate ions

  2. Acts on exocrine portion of pancreas and stimulates the cells to secrete glucagon

  3. Acts on gastric glands and stimulates secretion of HCl and Pepsinogen

  4. Stimulates secretion of gastric lipase from stomach


Correct Option: A

Which of the following is the primary absorptive process in the large intestine?

  1. Active transport of $Na^+$ from the lumen to the blood

  2. Absorption of amino acids and fructose

  3. Active transport of potassium from the lumen to the blood

  4. Active absorption of $HCO _3$ into the blood


Correct Option: A

Choose the odd one w.r.t. locations of source cells for hormone.

  1. Gastrin

  2. Enterogastrone

  3. Secretin

  4. Duocrinin


Correct Option: A
Explanation:

The gastrin hormone is secreted by the pyloric stomach located adjacent to the duodenum. This hormone stimulates the gastric glands to release gastric juice and regulates the movement of the stomach. 

Secretin is produced by the small intestinal mucosa region. It may inhibit the gastrin secretion and stomach movement. Both enterogastrone and duocrinin hormones are released from duodenal mucosa. Enterogastrone regulates gastric contraction and inhibits production of gastric juice. Duocrinin stimulates the viscous mucosa secretion from Brunner's gland into the intestinal juice. 
So, the correct answer is option A, Gastrin. 

The hormone responsible for vagus nerve activity is

  1. CCK

  2. Secretin

  3. Gastrin

  4. GIP


Correct Option: C

Which one of the following does not match is biological category of chemical substance.

  1. Gastrin

  2. Creatinine

  3. Oxytocin

  4. Renin


Correct Option: A
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