Digestive System (Part-I)

21. Pepsin digests: [S.S.C. Online MTS (T-1) 9.01.2017 (Shift-I)]

(a) proteins in stomach
(b) carbohydrates in mouth
(c) fats in duodenum
(d) minerals in ileum

Correct Answer: (a) proteins in stomach

Solution:Pepsin is the main proteolytic enzyme in the stomach. It breaks down large protein molecules into smaller polypeptides, initiating protein digestion. It functions optimally in the highly acidic environment of the stomach.

22. Which enzyme is present in pancreatic juice responsible for the digestion of proteins? [S.S.C. Online MTS (T-1) 14.08.2019 (Shift-I)]

(a) Trypsin
(b) Pepsin
(c) Amylase
(c) Amylase

Correct Answer: (a) Trypsin

Solution:The pancreas secretes several proteolytic (protein-digesting) enzymes as part of pancreatic juice, which is released into the small intestine. Trypsin is one of the most important of these enzymes. It is secreted as inactive trypsinogen and activated in the small intestine, where it then breaks down proteins and polypeptides into smaller peptides.

23. If the stomach did not produce any hydrochloric acid, which enzyme will not function? [S.S.C. Online Graduate Level (T-1) 11.08.2017 (Shift-III) S.S.C. Online MTS (T-1) 21.09.2017 (Shift-I)]

(a) Ptyalin
(b) Rennin
(c) Pepsin
(d) Lipase

Correct Answer: (c) Pepsin

Solution:Hydrochloric acid (HCl) in the stomach is crucial for activating pepsin. Pepsin is secreted in an inactive form called pepsinogen. HCl provides the acidic environment necessary to convert pepsinogen into active pepsin. Without HCl, pepsinogen would not be activated, and protein digestion in the stomach would be severely impaired.

24. How does hydrochloric acid help in facilitating the action of pepsin? [S.S.C. Online CGL (T-1) 02.12.2022 (Shift-II)]

(a) Hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin.
(b) Hydrochloric acid helps break down pepsin.
(c) Hydrochloric acid creates an alkaline medium which facilitates the action of the enzyme pepsin.
(d) Hydrochloric acid creates a basic medium which facilitates the action of the enzyme pepsin.

Correct Answer: (a) Hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin.

Solution:Hydrochloric acid does two main things:

It denatures (unfolds) proteins, making them more accessible for pepsin to break down.
Most importantly, it creates the highly acidic pH (around 1.5-3.5) that is optimal for pepsin's activity and essential for converting inactive pepsinogen into active pepsin.

25. Name the catalyst used to convert milk into curd: [S.S.C. Online CHSL (T-1) 8.01.2017 (Shift-I)]

(a) Pepsin
(b) Invertase
(c) Lactase
(d) Diastase

Correct Answer: (c) Lactase

Solution:Milk is converted into curd or yogurt by the process of fermentation. Milk consists of globular proteins called casein. The curd forms because of the chemical reaction between the lactic acid bacteria and casein. Thus, lactase is the catalyst used in the conversion of milk into curd.

26. _____ bacteria are helpful in making curd. [S.S.C. Online Constable GD 15.02.2019 (Shift-II)]

(a) Bacillus Coagulans
(b) Bifidobacterium bifidum
(c) Lactobacillus acidophilus
(d) Lactic acid

Correct Answer: (c) Lactobacillus acidophilus

Solution:Lactobacillus acidophilus is a well-known species of lactic acid bacteria commonly used in the production of curd (yogurt) and other fermented dairy products. These bacteria convert lactose into lactic acid, causing the milk to curdle and giving curd its characteristic tangy flavor.

27. Which of the following induces souring of milk? [S.S.C. Online CHSL (T-1) 21.01.2017 (Shift-I)]

(a) Acetic Acid
(b) Citric Acid
(c) Ascorbic Acid
(d) Lactic Acid

Correct Answer: (d) Lactic Acid

Solution:The souring of milk is due to the production of lactic acid by bacteria fermenting lactose. The increase in lactic acid lowers the pH of the milk, leading to protein coagulation and the sour taste.

28. Which is the bacteria found in our intestines, which helps us to digest food? [S.S.C. Online Constable GD 1.03.2019 (Shift-II)]

(a) Lactobacillus acidophilus
(b) Staphylococcus aureus
(c) Clostridium botulinum
(d) Campylobacter jejuni

Correct Answer: (a) Lactobacillus acidophilus

Solution:Lactobacillus acidophilus is a probiotic bacterium commonly found in the human gut. It plays a beneficial role in digestion, helps maintain a healthy gut microbiome, and can aid in breaking down certain food components.

29. Which of the following acid is found in milk? [S.S.C. Online Constable GD 19.02.2019 (Shift-II)]

(a) Hydrochloric acid
(b) Lactic acid
(c) Ascorbic acid
(d) Tannic acid

Correct Answer: (b) Lactic acid

Solution:While fresh milk is slightly acidic, as milk sours (due to bacterial action), lactic acid is produced, making the milk distinctly acidic. Hence, lactic acid is the acid prominently associated with milk, especially when it goes sour.