**Question:** A man not able to digest carbohydrate will be deficient in

A. Invertase
B. Amylase
C. Lactase
D. Lipase

**Core Concept:**
Carbohydrate digestion is a crucial process in the human body, where carbohydrates are broken down into simpler sugars for absorption and utilization by cells. The main enzymes involved in carbohydrate digestion are invertase, amylase, lactase, and lipase.

**Why the Correct Answer is Right:**
Invertase is an enzyme responsible for the hydrolysis of sucrose (table sugar) into fructose and glucose. A deficiency of invertase would prevent the breakdown of sucrose, leading to its accumulation in the gut and causing gastrointestinal symptoms like diarrhea, abdominal pain, and bloating. This is known as sucrase deficiency or sucrase-isomaltase deficiency.

**Why Each Wrong Option is Incorrect:**
Amylase is an enzyme responsible for the breakdown of polysaccharides (complex carbohydrates) into maltose and glucose. A deficiency of amylase would not affect carbohydrate digestion, as amylase is involved in the breakdown of complex carbohydrates, not sucrose.

Lactase is an enzyme responsible for the hydrolysis of lactose (milk sugar) into glucose and galactose. A deficiency of lactase would cause lactose intolerance, leading to gastrointestinal symptoms when consuming lactose-rich food or drinks. This is distinct from carbohydrate digestion in general.

Dipase is an enzyme involved in the breakdown of fats (triacylglycerols) into glycerol and fatty acids. A deficiency of lipase would lead to lipid malabsorption and severe gastrointestinal symptoms upon consuming fats, not carbohydrate digestion.

**Clinical Pearl:**
A deficiency in carbohydrate digestion enzymes can cause specific gastrointestinal symptoms depending on the enzyme involved. For example, lactase deficiency results in lactose intolerance, while sucrase deficiency leads to sucrase-isomaltase deficiency and symptoms like abdominal pain, diarrhoea, and bloating after consuming sweet foods.

**Correct Answer:**
The correct answer is C. Lactase. A deficiency in lactase (lactose intolerance) would lead to malabsorption of lactose and subsequent gastrointestinal symptoms upon consuming lactose-rich food or drinks. The other options (A, B, and D) are involved in lipid or protein digestion, not carbohydrate digestion.

**Why Each Wrong Option is Incorrect:**
A. Invertase is involved in the breakdown of sucrose, not lactose, in carbohydrate digestion.
B. Amylase is involved in the breakdown of complex carbohydrates, not lactose, in carbohydrate digestion.
D. Lipase is involved in the breakdown of fats, not carbohydrates, in carbohydrate digestion.