This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Structure and function of protein, Subject name: Biochemistry
[{'content': 'An L isomer of monosaccharide formed in the human body is \nSelect and explain. \nA. L-Fructose, B. L-Erythrose, C. L-xylose, D. L-Xylulose', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Monosaccharides are those sugars that cannot be hydrolyzed into simpler carbohydrates. They may be classified as trioses, tetroses, pentoses, hexoses, or heptoses, depending upon the number of carbon atoms (3-7), and as aldoses or ketoses, depending on whether they have an aldehyde or ketone group. d and l isomerism: The designation of a sugar isomer as the d form or its mirror image as the l form is determined by its spatial relationship to the parent compound of the carbohydrates, the three-carbon sugar glycerose (glyceraldehyde).Pentoses of Physiological ImpoanceSugarBiochemical and ClinicalImpoanced-RiboseStructural component ofnucleic acids andcoenzymes, includingATP, NAD(P), and flavincoenzymesd-RibuloseIntermediate in the pentosephosphate pathwayd-ArabinoseConstituent of glycoproteinsd-XyloseConstituent ofglycoproteinsl-XyluloseExcreted in the urine inessential pentosuriaRef: Harper&;s Biochemistry; 30th edition; Chapter 15; Carbohydrates of Physiological Significance', 'role': 'assistant'}]