**Question:** Conversion of glucose to glucose-6 phosphate in human liver is by

A. Glucose-6-phosphatase
B. Glucose-6-phosphatase
C. Glucose-6-phosphatase
D. Glucose-6-phosphatase

**Correct Answer:** D. Glucose-6-phosphatase

**Core Concept:**
The process of converting glucose to glucose-6 phosphate is an essential step in the glycolysis pathway, which occurs in the cytoplasm of hepatocytes (liver cells). This process is part of the liver's role in maintaining blood glucose levels and maintaining energy homeostasis in the body.

**Why the Correct Answer is Right:**
Glucose-6-phosphatase is the enzyme responsible for catalyzing the hydrolysis of glucose-6-phosphate to glucose in the liver. This enzyme plays a crucial role in the final step of glycolysis, where glucose-6-phosphate is converted to glucose, which can be released into the bloodstream to be used by other body cells for energy production.

**Why Each Wrong Option is Incorrect:**
A. Glucose-6-phosphatase (Option A) is the enzyme that catalyzes the hydrolysis of glucose-6-phosphate to glucose, but it is not the correct answer. Glucose-6-phosphatase is the enzyme responsible for the reverse reaction, converting glucose to glucose-6-phosphate.

B. Glucose-6-phosphatase (Option B) is the enzyme that catalyzes the hydrolysis of glucose-6-phosphate to glucose, similar to Option A. However, as explained above, glucose-6-phosphatase is responsible for the reverse reaction of converting glucose to glucose-6-phosphate.

C. Glucose-6-phosphatase (Option C) is also the enzyme that catalyzes the hydrolysis of glucose-6-phosphate to glucose. Like Options A and B, glucose-6-phosphatase is responsible for the reverse reaction of converting glucose to glucose-6-phosphate.

D. Glucose-6-phosphatase (Option D) is the correct enzyme responsible for the hydrolysis of glucose-6-phosphate to glucose in the liver. This enzyme plays a crucial role in maintaining blood glucose levels and ensuring energy homeostasis throughout the body.

**Clinical Pearl:** Glucose-6-phosphatase is a vital enzyme in the liver, helping to regulate blood glucose levels and maintain energy homeostasis in the body. This is particularly important in ensuring adequate glucose supply to tissues and organs for energy production through glycolysis.

**Why the Correct Answer is Right:**
Glucose-6-phosphatase is responsible for the hydrolysis of glucose-6-phosphate to glucose, which is essential for maintaining blood glucose levels and ensuring energy homeostasis throughout the body. In contrast, the other options refer to enzymes that catalyze the reverse reaction, converting glucose to glucose-6-phosphate.