Mix Examples- Digestion and Absorption Questions in English

(B) The statement in option $B$ is incorrect.
About $90 \%$ of all nutrient absorption occurs throughout the small intestine,not just the proximal part.
The small intestine is the primary site for the digestion and absorption of nutrients.
While the duodenum (proximal part) is the major site for digestion,the majority of absorption occurs in the jejunum and ileum.
Therefore,the claim that $40 \%$ of total absorption happens specifically in the proximal part is inaccurate.

(B) Statement $I$ is true: Bile is produced by the liver and stored in the gall bladder.
Statement $II$ is false: The common bile duct is formed by the union of the common hepatic duct and the cystic duct,not just the right and left hepatic ducts.
Statement $III$ is true: The hepato-pancreatic duct opens into the duodenum,which is the proximal part of the small intestine.
Statement $IV$ is true: The pancreas is a compound (mixed) gland consisting of both exocrine and endocrine parts.
Statement $V$ is true: Pepsinogen is secreted by chief cells and activated by $HCl$ into pepsin.
Statement $VI$ is true: Carboxypeptidase acts on peptides to convert them into dipeptides and amino acids.
Therefore,all statements are true except $II$.

(D) $I.$ Correct: The tongue is attached to the floor of the oral cavity by the frenulum.
$II.$ Incorrect: The upper surface of the tongue has small projections called papillae,which bear taste buds. The lower surface is smooth.
$III.$ Correct: The pharynx serves as a common passage for both food and air.
$IV.$ Incorrect: The opening of the stomach into the duodenum is guarded by the pyloric sphincter. The sphincter of Oddi guards the opening of the hepatopancreatic duct into the duodenum.
$V.$ Correct: The colon is divided into four parts: ascending,transverse,descending,and sigmoid colon.
Therefore,statements $I, III,$ and $V$ are correct.

(D) Statement $I$ is false because herbivores possess a wide variety of digestive enzymes,especially cellulases,to digest plant material.
Statement $II$ is true as digestive enzymes are broadly classified into amylases (carbohydrates),proteinases (proteins),lipases (fats),and nucleases (nucleic acids).
Statement $III$ is false because proteinases are secreted in inactive forms (proenzymes or zymogens) to prevent the digestion of the body's own cellular proteins.
Statement $IV$ is false because cholecystokinin is a hormone secreted by the intestinal mucosa,not an enzyme secreted by the pancreas.

(D) The process of digestion is completed in the small intestine,where the majority of nutrient absorption also occurs. The large intestine does not play a role in digestion; instead,its primary functions are the absorption of water,some minerals,and certain drugs,as well as the storage of undigested food (feces) before elimination. Therefore,option $D$ is the incorrect statement.

(B) The correct matches are as follows:
$a.$ Lysozyme is an antibacterial enzyme present in saliva.
$b.$ Peptic cells (also known as chief cells) secrete the proenzyme pepsinogen.
$c.$ Saliva is produced by salivary glands,including the sublingual gland.
$d.$ Oxyntic cells (also known as parietal cells) secrete $HCl$ and intrinsic factor.
Therefore,the correct matching is $a(ii), b(iv), c(iii), d(i)$.

(D) The pancreas plays a crucial role in digestion by secreting pancreatic juice into the small intestine.
Pancreatic juice contains various enzymes:
$1$. Amylase,which is responsible for the digestion of carbohydrates.
$2$. Trypsinogen,chymotrypsinogen,and carboxypeptidase,which are essential for the digestion of proteins.
$3$. Lipase,which is required for the digestion of fats (lipids).
Therefore,if the pancreas is removed,the digestion of all these food components—carbohydrates,proteins,and fats—will be significantly affected.

(A) The presence of fats in the duodenum triggers the release of hormones such as $CCK$ (Cholecystokinin) and $GIP$ (Gastric Inhibitory Peptide).
These hormones act on the stomach to inhibit gastric motility and slow down the rate of gastric emptying.
This mechanism ensures that the small intestine has sufficient time to emulsify and digest the complex fat molecules.
Therefore,both the Assertion and the Reason are correct,and the Reason provides the correct explanation for the Assertion.

(A-D) Goblet cells secrete mucus. Chymotrypsin is a pancreatic enzyme.
$(b)$ Fats are broken down into di- and monoglycerides by lipase. Amylase digests carbohydrates.
$(c)$ Oxyntic cells (also known as parietal cells) secrete $HCl$. Chief cells secrete pepsinogen.
$(d)$ Saliva contains salivary amylase which digests starch. Protein digestion begins in the stomach.

(C) The energy values (gross calorific values) for the substrates are approximately:
$1 \; g$ of glucose = $4.1 \; kcal$
$1 \; g$ of protein = $5.65 \; kcal$
$1 \; g$ of fat = $9.45 \; kcal$
Now,calculating the energy for each option:
$(a) 1 \; g \text{ of fat} = 9.45 \; kcal$
$(b) 1 \; g \text{ of protein} = 5.65 \; kcal$
$(c) 1 \; g \text{ of glucose} = 4.1 \; kcal$
$(d) 0.5 \; g \text{ of protein} + 0.5 \; g \text{ of glucose} = (0.5 \times 5.65) + (0.5 \times 4.1) = 2.825 + 2.05 = 4.875 \; kcal$
Arranging in ascending order of energy released:
$4.1 \; kcal (c) < 4.875 \; kcal (d) < 5.65 \; kcal (b) < 9.45 \; kcal (a)$
Therefore,the order is $(c) < (d) < (b) < (a)$.

(D) Saliva is secreted by the salivary glands in the oral cavity.
It performs several vital functions:
$1$. It contains mucus which helps in lubricating and adhering the masticated food particles into a bolus.
$2$. The bolus is then conveyed into the pharynx and then into the oesophagus by swallowing or deglutition.
$3$. Saliva also contains electrolytes ($Na^+$,$K^+$,$Cl^-$,$HCO_3^-$) and enzymes like salivary amylase and lysozyme.
Therefore,all the given options are correct functions of saliva.

(A) The correct matching is as follows:
$i$. Duodenum is $U$-shaped $(i-b)$.
$ii$. Stomach is $J$-shaped $(ii-c)$.
$iii$. Tongue is triangular in shape $(iii-d)$.
$iv$. Appendix is a vestigial organ that is worm-like in appearance $(iv-a)$.
Therefore,the correct sequence is $i-b, ii-c, iii-d, iv-a$.

(C) The correct matching is as follows:
$i$. Liver: The liver is responsible for the storage of glycogen,which is the stored form of glucose in the body $(i-b)$.
$ii$. Stomach: The gastric glands in the stomach secrete $HCl$ (hydrochloric acid) to aid in digestion $(ii-c)$.
$iii$. Gall bladder: The gall bladder stores and concentrates the bile produced by the liver $(iii-d)$.
$iv$. Pancreas: The pancreas contains alpha cells in the Islets of Langerhans that secrete the hormone glucagon $(iv-a)$.
Therefore,the correct sequence is $i-b, ii-c, iii-d, iv-a$.

(B) $Statement I$ is incorrect because the cardiac sphincter (gastro-oesophageal sphincter) is located between the oesophagus and the stomach, preventing the regurgitation of food from the stomach back into the oesophagus.
$Statement II$ is incorrect because the pyloric sphincter is located between the stomach and the duodenum, regulating the flow of food from the stomach into the duodenum.

(C) Kwashiorkor is a form of protein-energy malnutrition characterized by a deficiency of protein in the diet.
Symptoms of Kwashiorkor include stunted growth,oedema (swelling due to fluid retention,especially in the lower legs),poor brain development,anemia,loss of appetite,and a protruding belly (often due to hepatomegaly or ascites).
Yellow colouration of the skin (jaundice) is typically associated with liver dysfunction or bile duct obstruction,not specifically with Kwashiorkor.
Therefore,yellow colouration of the skin is $NOT$ a characteristic symptom of Kwashiorkor.