A Level Biology Practice Exam

What is the chemical formula for glucose?

1. C5H10O5

2. C6H12O6

3. C6H6O6

4. C4H8O4

The correct answer is: C6H12O6

The chemical formula for glucose, which is a simple sugar and an essential carbohydrate in biology, is represented as C6H12O6. This formula indicates that each molecule of glucose consists of six carbon atoms, twelve hydrogen atoms, and six oxygen atoms. Glucose plays a pivotal role in energy metabolism and is a key product of photosynthesis in plants. Organisms use glucose as a primary energy source for cellular processes, and it is also involved in various metabolic pathways. The other options do not accurately depict the composition of glucose. For example, C5H10O5 suggests a pentose sugar, which is not glucose but rather ribose or a similar pentose carbohydrate. C6H6O6 represents an incorrect molecular structure as glucose does not contain six hydrogen atoms for every six carbons and six oxygens in that arrangement. Lastly, C4H8O4 would correspond to a different compound, likely a tetrose, which lacks the correct number of carbon and hydrogen atoms that characterize glucose. Therefore, B is the correct answer, as it accurately reflects the molecular structure of glucose.