NEET Biology Digestion and Absorption MCQs Set 19

Answer: (a) Maltose

Explanation:
1. Ptyalin (salivary amylase) hydrolyses starch into maltose.

Teacher's Note:
1. The pH of mouth is nearly neutral.
2. Ptyalin forms maltose.

Answer: (d) Milk, changing casien into calcium paracaseinate at 1-3 PH

Explanation:
1. Rennin acts in the acidic stomach (pH 1-3) and changes casein of milk to calcium paracaseinate.

Teacher's Note:
1. It is found in infant stomach.
2. Rennin acts at low pH.

Answer: (d) Peristalsis

Explanation:
1. Rhythmic wave-like contraction of the alimentary canal muscles that moves food is peristalsis.

Teacher's Note:
1. Deglutition means swallowing.
2. Peristalsis moves food.

Answer: (a) Low pH

Explanation:
1. Hydrochloric acid, i.e. the low pH of the stomach, converts pepsinogen to active pepsin.

Teacher's Note:
1. Pepsin also activates more pepsinogen.
2. Low pH activates pepsinogen.

Answer: (d) All of the above

Explanation:
1. Mucus is secreted by goblet and mucous cells in the stomach, duodenum and large intestine.

Teacher's Note:
1. It protects and lubricates.
2. All of them secrete mucus.

Answer: (a) Gastrin

Explanation:
1. Gastrin from the stomach wall stimulates secretion of gastric juice.

Teacher's Note:
1. Enterogastrone inhibits it.
2. Gastrin stimulates gastric juice.

Answer: (c) Proteins will not be adequately hydrolysed by pepsin into proteoses and peptones

Explanation:
1. Parietal cells secrete HCl and intrinsic factor, so without them proteins would not be adequately hydrolysed by pepsin.

Teacher's Note:
1. Pepsin works at acidic pH.
2. Less HCl means poor protein digestion.

Answer: (a) Chyme

Explanation:
1. Food in the stomach is churned into a semi-fluid acidic mass called chyme.

Teacher's Note:
1. Bolus is the food in the mouth.
2. Chyme forms in the stomach.

Answer: (b) Starch

Explanation:
1. Rice is rich in starch, a polysaccharide.

Teacher's Note:
1. Cellulose is in vegetables.
2. Rice contains starch.

Answer: (a) Rennin

Explanation:
1. Rennin curdles milk protein in infants' stomachs and so aids milk digestion.

Teacher's Note:
1. Amylase acts on starch.
2. Rennin digests milk.

Answer: (b) a–Amylase

Explanation:
1. Alpha amylase works best at neutral or slightly alkaline pH and is inactivated by stomach acid, unlike proteases such as pepsin.

Teacher's Note:
1. Salivary amylase stops in the stomach.
2. Amylase does not act at low pH.

Answer: (c) Sucrose

Explanation:
1. Sucrose is a disaccharide made of glucose and fructose. The others are monosaccharides.

Teacher's Note:
1. Maltose and lactose are also disaccharides.
2. Sucrose is a disaccharide.

Answer: (d) Lactose

Explanation:
1. Glucose combines with galactose to form lactose, the milk sugar.

Teacher's Note:
1. Maltose is glucose plus glucose.
2. Lactose is glucose plus galactose.

Answer: (d) 1.50 to 2.60

Explanation:
1. Pepsin is active in strongly acidic medium, about pH 1.5 to 2.6.

Teacher's Note:
1. At higher pH it is inactive.
2. Pepsin needs pH 1.5 to 2.6.

Answer: (a) Proteins

Explanation:
1. Pepsin in the stomach begins the digestion of proteins.

Teacher's Note:
1. Fats are mostly digested in the intestine.
2. Stomach digests proteins.

Answer: (b) Emulsify fats for digestion

Explanation:
1. Bile does not contain enzymes; its bile salts emulsify fats so that lipases can digest them.

Teacher's Note:
1. Emulsification increases the surface area.
2. Bile emulsifies fats.

Answer: (c) Liver

Explanation:
1. The liver detoxifies harmful substances such as drugs and alcohol.

Teacher's Note:
1. The kidney excretes them.
2. Liver detoxifies.

Answer: (d) Activate pepsinogen to pepsin

Explanation:
1. HCl of gastric juice provides acid pH that activates pepsinogen to pepsin.

Teacher's Note:
1. It also kills bacteria.
2. HCl activates pepsinogen.

Answer: (c) Peristalsis

Explanation:
1. Peristalsis is the wave of muscular contraction in the alimentary canal. Systole and diastole belong to the heart.

Teacher's Note:
1. It moves food forward.
2. Peristalsis is the gut movement.

Answer: (b) Intestinal juice

Explanation:
1. Succus entericus is the intestinal juice secreted by the glands of the small intestine.

Teacher's Note:
1. It has enzymes like maltase.
2. Succus entericus is intestinal juice.

Answer: (b) enterokinase to typsinogen

Explanation:
1. HCl activates pepsinogen, and likewise enterokinase activates trypsinogen: an activator to its inactive enzyme.

Teacher's Note:
1. The other pairs are not activator and zymogen.
2. Activator and its proenzyme.

Answer: (b) Production of mucin

Explanation:
1. Goblet cells in the lining of the gut secrete mucus (mucin).

Teacher's Note:
1. Mucus protects the lining.
2. Goblet cells make mucin.

Answer: (b) Ptyalin

Explanation:
1. Gastrin, glucagon and secretin are hormones, while ptyalin is an enzyme.

Teacher's Note:
1. Hormones are chemical messengers.
2. Ptyalin is the enzyme.

Answer: (a) alkaline in nature

Explanation:
1. Pancreatic juice contains sodium bicarbonate and so is alkaline.

Teacher's Note:
1. It neutralises acidic chyme.
2. Pancreatic juice is alkaline.

Answer: (a) Ampulla of Vater

Explanation:
1. Bile and pancreatic juice enter the duodenum through the common hepatopancreatic duct opening at the ampulla of Vater.

Teacher's Note:
1. The sphincter of Oddi guards it.
2. Both juices pass the ampulla of Vater.

Answer: (a) enzymes are secreted in inactive form

Explanation:
1. Pancreatic enzymes are secreted as inactive zymogens, so the pancreas is not digested by its own enzymes.

Teacher's Note:
1. They are activated in the duodenum.
2. Enzymes are secreted inactive.

Answer: (b) Fat

Explanation:
1. Fat in the diet stimulates the release of bile, so bile secretion increases with fat concentration.

Teacher's Note:
1. CCK causes gall bladder contraction.
2. Fat increases bile flow.