A Level Biology Practice Exam

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What is ribose?

A pentose monosaccharide present in RNA molecules
A component of DNA
A disaccharide found in cells
A type of fatty acid

The correct answer is: A pentose monosaccharide present in RNA molecules

Ribose is a pentose monosaccharide, which means it is a sugar molecule made up of five carbon atoms. It plays a crucial role as a constituent of RNA (ribonucleic acid) molecules, where it forms the backbone of the structure, linking up with phosphate groups and nitrogenous bases. This five-carbon structure is essential for the proper functioning and stability of RNA, allowing it to play a key role in protein synthesis and other cellular functions. The other options do not accurately describe ribose. While DNA contains a related sugar called deoxyribose, ribose itself is not a component of DNA. Ribose is not a disaccharide, which consists of two monosaccharide units bonded together. Lastly, ribose is not a fatty acid; fatty acids are long hydrocarbon chains typically found in lipids, while ribose is a carbohydrate. Thus, the identification of ribose as a pentose monosaccharide in RNA molecules is fundamentally correct.