**Question:** Glucose may be synthesised from:

A. Starch
B. Fatty acids
C. Lactate
D. Alanine

**Core Concept:** Gluconeogenesis is a process by which glucose is synthesized in the liver from non-carbohydrate sources during fasting or when blood glucose levels are low.

**Why the Correct Answer is Right:** Gluconeogenesis is a crucial process in maintaining blood glucose levels in the body. Among the options provided, glucose can be synthesized from lactate (C), which is a product of anaerobic glycolysis in muscles during exercise or hypoxia. In these conditions, lactate produced is converted into glucose in the liver through gluconeogenesis.

**Why Each Wrong Option is Incorrect:**

A. Starch (Option A) is a complex carbohydrate, which is broken down into glucose through the process of digestion and absorption for immediate energy needs. Starch is not a substrate for gluconeogenesis.

B. Fatty acids (Option B) are the primary energy source when carbohydrate and protein stores are depleted. They are not substrates for gluconeogenesis.

D. Alanine (Option D) is an amino acid, and gluconeogenesis primarily involves amino acids like glycerol, lactate, and alanine. However, alanine is not the primary source of glucose during gluconeogenesis. Lactate is a more suitable substrate for gluconeogenesis.

**Clinical Pearl:** Gluconeogenesis is a dynamic process that helps maintain blood glucose levels during stress situations like starvation, trauma, or infections. Understanding the process and its substrates is crucial for medical students and practitioners alike.

**Correct Answer:** C. Lactate

**Explanation:** Gluconeogenesis occurs when there is a need for glucose production in the body, which is primarily triggered by low blood glucose levels. In the context of this question, lactate (Option C) is a suitable substrate for gluconeogenesis, ensuring that glucose is produced when blood glucose levels are low. This process helps maintain the body's energy supply during fasting, stress, or hypoglycemic situations.