Which of the following enzymes is not involved in the digestion of carbohydrates?

Appeared in: RRB Nsg. Superintendent-21 July 2019 (Shift-2nd)

Explanation

Lipase is the correct answer as its primary function is the digestion of fats (lipids), not carbohydrates.
It is an enzyme secreted mainly by the pancreas.
Lipase hydrolyzes triglycerides (fats) into their constituent components: fatty acids and glycerol, which can then be absorbed by the intestines.
Since its substrate is lipids, it plays no role in the breakdown of carbohydrates like starches or sugars.

Option A: Lactase is an enzyme specifically involved in carbohydrate digestion. It is a brush border enzyme in the small intestine.
Option B: Sucrase is an enzyme that digests carbohydrates. It is found in the small intestine.
Option C: Amylase is a key enzyme in carbohydrate digestion. It is secreted by both the salivary glands and the pancreas.

Visual 1: Diagram - An illustration of the human digestive system highlighting the organs that secrete digestive enzymes (salivary glands, pancreas, small intestine) and where different macronutrients are broken down.
Visual 2: Flowchart - A flowchart showing the breakdown of carbohydrates, fats, and proteins from complex molecules to absorbable units, indicating the specific enzymes involved at each step.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Role of digestive enzymes in macronutrient metabolism as background academic context rather than a clinical decision trigger.
Understanding enzyme function is crucial for diagnosing and managing digestive disorders. For example, a deficiency in lactase causes lactose intolerance, a common condition nurses encounter.
In conditions like pancreatitis or cystic fibrosis, pancreatic enzyme secretion (including lipase) is impaired. Nurses administer pancreatic enzyme replacement therapy (PERT) with meals to aid digestion and prevent malabsorption.
Nurses monitor for signs of malabsorption, such as steatorrhea (fatty stools), which indicates poor fat digestion due to lipase deficiency and requires intervention.

How to Approach the Question

First, identify the negative keyword in the question: 'not'. This means you are looking for the option that does not fit with the others.
The question is about enzymes that digest 'carbohydrates'.
Recall the function of each enzyme listed in the options.
Lactase digests lactose (a carbohydrate).
Sucrase digests sucrose (a carbohydrate).
Amylase digests starch (a carbohydrate).

Concept Tested & Keywords

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Practise the full RRB Nsg. Superintendent-21 July 2019 (Shift-2nd)

Attempt every question from this paper in a timed mock, then review the full solution for each one.