A disaccharide can be made by joining any of the following EXCEPT:

a) fructose and glucose

b) ribose and galactose

c) deoxyribose and glucose

d) glucose and sucrose

e) fructose and fructose 


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The correct answer is D. There are very few things you need to hardcore memorize in Biology 1A, but one is the general idea of what is considered a monosaccharide and what is considered to be a disaccharide. In this case, remember that the prominent monosaccharides include glucose and fructose. Deoxyribose is not a common one, but it is in DNA and from that, you should know that it is a monosaccharide. A common disaccharide is sucrose, which is a disaccharide of glucose and fructose, and thus, the answer is D since glucose and sucrose would make a trisaccharide not a disaccharide.