NEET > Human Physiology

Explore popular questions from Human Physiology for NEET. This collection covers Human Physiology previous year NEET questions hand picked by popular teachers.


Q 1.    

Correct4

Incorrect-1

Which cells of 'Crypts of Lieberkuhn' secreteantibacterial lysozyme?

Paneth cells

B

Zymogen cells

C

Kupffer cells

D

Argentaffin cells

Explanation

Paneth cells, present in the bottom of cryptsof Lieberkuhn, are rich in zinc and contain acidophilicgranules. There is evidence that these cells secreteantibacterial lysozyme. Zymogen cells or peptic cellsare present in stomach and secrete pepsinogen.
Kupffer cells are present in liver. They are phagocytic in nature and engulf disease causing microorganisms,dead cells, etc. Argentaffin cells, found in crypts of Lieberkuhn, synthesise hormone secretin and {tex} 5 - {/tex} hydroxytryptamine.

Q 2.    

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Incorrect-1

Which of the following options best represents the enzyme composition of pancreatic juice?

A

Amylase, Pepsin, Trypsinogen, Maltase

B

Peptidase, Amylase, Pepsin, Rennin

Lipase, Amylase, Trypsinogen, Procarboxypeptidase

D

Amylase, Peptidase, Trypsinogen, Rennin

Explanation

The pancreatic juice contains sodium bicarbonate, three proenzymes; trypsinogen,chymotrypsinogen and procarboxypeptidase and some enzymes such as elastase, pancreatic {tex} \square -{/tex} amylase,DNase, RNase and pancreatic lipase. It helps in the digestion of starch, proteins, fats and nucleic acids.

Q 3.    

Correct4

Incorrect-1

A baby boy aged two years is admitted to playschool and passes through a dental check-up. The dentist observed that the boy had twenty teeth. Which teeth were absent?

A

Canines

Pre-molars

C

Molars

D

Incisors

Explanation

Boy aged two years will have milk teeth. Milk teeth of man include 8 incisors, 4 canines,8 molar. Premolars are absent.

Q 4.    

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Incorrect-1

Which hormones do stimulate the production of pancreatic juice and bicarbonate?

A

Angiotensin and epinephrine

B

Gastrin and insulin

Cholecystokinin and secretin

D

Insulin and glucagon

Explanation

Cholecystokinin pancreozymin (CCK-PZ) is a hormone secreted from small intestine. It stimulates the gall bladder to release bile and pancreas to secrete and release digestive enzymes in the pancreatic juice. Hormone secretin is secreted from duodenum and releases bicarbonates in the pancreatic juice. It also increases secretion of bile and decreases gastric secretion and motility.

Q 5.    

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Incorrect-1

Which of the following guards the opening of hepatopancreatic duct into the duodenum?

A

Pyloric sphincter

Sphincter of Oddi

C

Semilunar valve

D

Ileocaecal valve

Explanation

The sphincter of Oddi is a muscular valve that controls the flow of digestive juices (bile and pancreatic juice) through the hepatopancreatic duct into the duodenum.

Q 6.    

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Incorrect-1

In the stomach, gastric acid is secreted by the

A

peptic cells

B

acidic cells

C

gastrin secreting cells

parietal cells.

Explanation

Parietal cells are large cells present on the side walls of the gastric glands. They lie against the basement membrane. They secrete hydrochloric acid and Castle's intrinsic gastric factor that helps in the absorption of vitamin {tex} \mathrm { B } _ { 12 } {/tex} in the ileum.

Q 7.    

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Incorrect-1

The enzyme that is not present in succus entericus is

A

nucleosidase

B

lipase

C

maltase

nuclease.

Explanation

Succus entericus or intestinal juice (pH = 7.8 ) refers to the secretion of glands of small intestine. It contains many enzymes {tex} v i z {/tex} maltase,isomaltase, lipase, lactase, {tex} \square- {/tex} dextrinase, enterokinase, aminopeptidase, nucleotidase, nucleosidase, etc., for the digestion of carbohydrates, proteins, fats, nucleic acids etc. Enzyme nuclease is not a digestive enzyme.It is not present in any digestive juice.

Q 8.    

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Incorrect-1

The primary dentition in human differs frompermanent dentition in not having one of the following type of teeth.

A

Molars

B

Incisors

C

Canines

Premolars

Explanation

Milk/primary teeth of man include 8 incisors, 4 canines and 8 molars (premolars are absent). Molars of milk teeth are shed off and premolars of permanent teeth take their place. The permanent teeth are 8 incisors, 4 canines, 8 premolars and 12 molars. Thus 12 teeth (8 premolars and 4 molars) are monophyodont (teeth which grow only once in life). Dental formulae of milk teeth and permanent teeth of human are given below.

{tex}\frac{2120}{2120}\square 2=20 \quad\quad\quad \quad\quad\quad \frac{2123}{2123}\square 2=32{/tex}
Milk Teeth{tex}\quad\quad\quad\quad\quad\quad{/tex}Permanant teeth

Q 9.    

Correct4

Incorrect-1

Gastric juice of infants contains

pepsinogen, lipase, rennin

B

amylase, rennin, pepsinogen

C

maltase, pepsinogen, rennin

D

nuclease, pepsinogen, lipase.

Explanation

The secretion of the cells of the gastric glands form gastric juice with pH 2 to 3.7. It contains two proenzymes, pepsinogen and prorennin and enzyme gastric lipase, mucous and hydrochloric acid.Rennin (chymosin) is responsible for clotting milk by acting on soluble milk protein caseinogen, and
converting it into insoluble casein. This ensures that milk remains in stomach long enough to be acted on by protein digesting enzymes. Rennin’s concentration is highest in young mammals (as their primary diet is milk) which reduces gradually with age.

Q 10.    

Correct4

Incorrect-1

Which of the following statements is not correct?

A

Oxyntic cells are present in the mucosa of stomach and secrete HCl.

B

Acini are present in the pancreas and secrete carboxypeptidase.

Brunner's glands are present in thesubmucosa of stomach and secrete pepsinogen.

D

Goblet cells are present in the mucosa of intestine and secrete mucus.

Explanation

The Brunner's glands are branched tubular glands which occur only in the duodenum. Theysecrete alkaline watery fluid, a little enzyme and mucus. They open into the crypts of Lieberkuhn.

Q 11.    

Correct4

Incorrect-1

The initial step in the digestion of milk in humans is carried out by

A

lipase

B

trypsin

rennin

D

pepsin.

Explanation

Rennin is secreted by peptic cells present in epithelium of gastric glands. It is found in the gastric juice of human beings during infancy and in calf. In adults gastric juice is devoid of rennin. It converts milk protein casein into paracasein, leading to milk coagulation.

Q 12.    

Correct4

Incorrect-1

Fructose is absorbed into the blood throughmucosa cells of intestine by the process called

A

active transport

facilitated transport

C

simple diffusion

D

co-transport mechanism.

Explanation

Fructose and mannose are absorbed through facilitated diffusion that is by the help of the carrier molecule. It is along the concentration gradient (higher concentration to low concentration).

Q 13.    

Correct4

Incorrect-1

Select the correct match of the digested products in humans given with their absorption site and mechanism

A

{tex} \begin{array} { l l } { \text { Glycerol, fatty acids } } \ -& { \text { Duodenum, move as , } } \\ { } & { \text { chylomicrons } } \end{array} {/tex}

B

{tex} \begin{array} { l l } { \text { Cholesterol, maltose } }\ - & { \text { Large intestine, } } \\ { } & { \text { active absorption } } \end{array} {/tex}

{tex} \begin{array} { l l } { \text { Glycine, glucose } }\ - & { \text { Small intestine } } \\ { } & { \text { active absorption } } \end{array} {/tex}

D

{tex} \begin{array} { l l } { \text { Fructose },\mathrm {Na^{+}} }\ - & { \text { Small intestine } } \\ { } & { \text { passive absorption } } \end{array} {/tex}

Explanation

Glycerol and fatty acids are absorbed in jejunum by diffusion into intestinal cells where they are converted into chylomicrons. Cholesterol is also absorbed by simple diffusion in small intestine. Maltose is broken into glucose and galactose which are absorbed by active transport into small intestine.
Fructose is absorbed by facilitated diffusion. Amino acids are also absorbed in small intestine, some by active transport and some by facilitated diffusion.

Q 14.    

Correct4

Incorrect-1

A healthy person eats of the following diet 5 gm raw sugar,4 gm albumin,10 gm pure buffalo ghee adultrated with 2 gm vegetable ghee(hydrogenated vegetable oil) and 5 gm ligin.How many calories he is likely to get?

A

126

B

164

C

112

144

Explanation

Physiological value is the energy produced by 1 gm of food on oxidation in the body. For carbohydrates it is 4.0 Kcal/g, for proteins it is 4.0 Kcal/g and it is 9.0 Kcal/g for fats. Lignin is a fibre that is present in plant cells but it does not produce energy. Hence,
5 g raw sugar will yield 5{tex} \times{/tex} 4.0 = 20.0 Kcal
4 g albumin will yield 4{tex} \times {/tex}4.0 = 16.0 Kcal
( 10 + 2 ) g of fat will yield 12 {tex} \times {/tex}9.0 = 108.0 Kcal
Total yield = 144 Kcal.

Q 15.    

Correct4

Incorrect-1

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

A

Pancreatic amylase {tex}\square{/tex} Salivary amylase {tex}\square{/tex} Lipases

B

Disaccharidase like maltase {tex}\square{/tex} Lipases {tex}\square{/tex} Nucleases

Salivary amylase {tex}\square{/tex} Pancreatic amylase {tex}\square{/tex} Disaccharidases

D

Salivary maltase {tex}\square{/tex} Carboxy peptidase {tex}\square{/tex} Trypsinogen

Explanation

(c) : Baked potatoes consist of starch which is a polysaccharide. In oral cavity, the food is mixed with saliva. The saliva contains an enzyme called salivary amylase (also called ptyalin) which converts starch into maltose, isomaltose and small dextrins. Salivary amylase is activated in the saliva by the chloride ions.



The pancreatic juice (present in small intestine) contains starch digesting enzyme, called pancreatic amylase which converts starch into maltose, isomaltose and α-­dextrins.



Further, disaccharidases such as maltase (present in intestinal juice in small intestine) breakdown disaccharides such as maltose into (monosaccharides) or simpler sugars.

Q 16.    

Correct4

Incorrect-1

Anxiety and eating spicy food together in an otherwise normal human, may lead to

indigestion

B

jaundice

C

diarrhoea

D

vomiting.

Explanation

Indigestion is the condition in which the food is not properly digested leading to a feeling of fullness. The causes of indigestion are inadequate enzyme secretion, anxiety, food poisoning, over eating and spicy food.

Q 17.    

Correct4

Incorrect-1

For its activity, carboxypeptidase requires

zinc

B

iron

C

niacin

D

copper.

Explanation

Carboxypeptidase is an enzyme synthesized in pancreas and secreted into small intestine. It contains Zn (II) ions as a metal ion cofactor. This enzyme helps in protein digestion and becomes active in alkaline medium. It is mainly involved in the conversion of large peptides or polypeptides into dipeptides and amino acids.

Q 18.    

Correct4

Incorrect-1

Where do certain symbiotic microorganismsnormally occur in human body?

Caecum

B

Oral lining and tongue surface

C

Vermiform appendix and rectum

D

Duodenum

Explanation

Q 19.    

Correct4

Incorrect-1

Two friends are eating together on a dining table. One of them suddenly starts coughing while swallowing some food. This coughing would have been due to improper movement of

epiglottiss

B

diaphragm

C

neck

D

tongue.

Explanation

This coughing would have been due to improper movement of epiglottis. Epiglottis is present in the laryngopharynx, which is the lowest part of pharynx. Laryngopharynx possess two apertures anterior slit-like glottis and posterior gullet. Glottis leads into trachea or wind pipe, which is closed by bilobed leaf-like cartilage, the epiglottis, during the swallowing of food-bolus. Hence, during eating one may suddenly coughs due to opening of epiglottis and movement of some food particles in the trachea.

Q 20.    

Correct4

Incorrect-1

The purplish red pigment rhodopsin contained in the rods type of photoreceptor cells of the human eye, is a derivative of

A

vitamin {tex} \mathrm { B } _ { 1 } {/tex}

B

vitamin {tex} \mathrm { C } {/tex}

C

vitamin {tex} \mathrm { D } {/tex}

vitamin {tex} \mathrm { A } {/tex}

Explanation

Vitamin A (retinol) is a fat-soluble vitamin that cannot be synthesized by mammals and othervertebrates and must be provided in the diet. It is a constituent of the visual pigment rhodopsin. Deficiency affects the eyes, causing night blindness.

Q 21.    

Correct4

Incorrect-1

One of the constituents of the pancreatic juice which is poured into the duodenum in humans is

trypsinogen

B

chymotrypsin

C

trypsin

D

enterokinase.

Explanation

Duodenum follows the stomach. It is somewhat C-shaped and about 25 cm. long. It receives the hepatopancreatic ampulla of the hepatopancreatic duct formed by the union of bile duct (from liver) and pancreatic duct (from pancreas) and whose opening is guarded by sphincter of Oddi. Pancreatic juice contains proenzymes-trypsinogen, chymotrypsinogen and procarboxypeptidase. In the presence of enterokinase (a protease of intestinal juice), inactive trypsinogen is converted to active trypsin. Trypsin then activates chymotrypsinogen and procarboxypeptidase into chymotrypsin and carboxypeptidase respectively. This enables simultaneous action of all pancreatic proteases for a rapid digestion of proteins. The bile provides alkaline medium for various reactions.

Q 22.    

Correct4

Incorrect-1

Which one of the following correctly represents the normal adult human dental formula?

A

{tex} \frac { 3 } { 3 } , \frac { 1 } { 1 } , \frac { 3 } { 2 } , \frac { 1 } { 1 } {/tex}

B

{tex} \frac { 2 } { 2 } , \frac { 1 } { 1 } , \frac { 3 } { 2 } , \frac { 3 } { 3 } {/tex}

{tex} \frac { 2 } { 2 } , \frac { 1 } { 1 } , \frac { 2 } { 2 } , \frac { 3 } { 3 } {/tex}

D

{tex} \frac { 3 } { 3 } , \frac { 1 } { 1 } , \frac { 3 } { 3 } , \frac { 3 } { 3 } {/tex}

Explanation

An adult human has 32 permanent teeth which are of four different types (heterodont dentition) namely, incisors (I), canine (C), premolars(PM) and molars (M). Arrangement of teeth in each half of the upper and lower jaw in the order I, C, PM, M is represented by a dental formula which in human is {tex} \frac { 2123 } { 2123 } {/tex} .

Q 23.    

Correct4

Incorrect-1

Carrier ions like {tex}\mathrm {Na^+}{/tex} facilitate the absorption of substances like

amino acids and glucose

B

glucose and fatty acids

C

fatty acids and glycerol

D

fructose and some amino acids.

Explanation

The absorption of glucose and amino acids is mediated by carrier ions like Na{tex}^+{/tex}. The concentration of {tex}\mathrm {Na^+}{/tex} is higher in the intestinal lumen compared to mucosal cells. {tex}\mathrm {Na^+}{/tex}, therefore moves into the cells along its concentration gradient and simultaneously glucose is transported into the intestinal cells. Thus {tex}\mathrm {Na^+}{/tex} diffuses into the cell and it drags glucose along with it. The intestinal {tex}\mathrm {Na^+}{/tex} gradient is the immediate energy source. The mechanism for transport of amino acid is same as glucose. Fructose absorption does not require energy and is independent of {tex}\mathrm {Na^+}{/tex} transport.

Q 24.    

Correct4

Incorrect-1

If for some reason our goblet cells are nonfunctional, this will adversely affect

A

production of somatostatin

B

secretion of sebum from the sebaceousglands

C

maturation of sperms

smooth movement of food down theintestine.

Explanation

The intestinal mucosal epithelium has goblet cells which secrete mucus. The mucuslubricates the food for an easy passage. Thus, if for some reason goblet cells become non-functional, it will adversely affect smooth movement of food down the intestine. It along with bicarbonates from the pancreas also protects the intestinal mucosa from acid as well as provide an alkaline medium for enzymatic activities.

Q 25.    

Correct4

Incorrect-1

If for some reason the parietal cells of the gut epithelium become partially non-functional,what is likely to happen?

A

The pancreatic enzymes and specially the trypsin and lipase will not work efficiently.

B

The pH of stomach will fall abruptly.

C

Steapsin will be more effective.

Proteins will not be adequately hydrolysed by pepsin into proteoses and peptones.

Explanation

Parietal or oxyntic cells secrete HCl (due to which pH of stomach is highly acidic) and intrinsic factor. Parietal glands also secrete pepsinogen to which hydrochloric acid acts to convert it into pepsin.Pepsin in return causes digestion of protein. If parietal cells become non-functional it will directly affect protein digestion.