Which one of the following sets of monosaccharides forms sucrose?

• A

  $\alpha$-D-galactopyranose and $\alpha$-D-glucopyranose
• Correct answer
  B

  $\alpha$-D-glucopyranose and $\beta$-D-fructofuranose
• C

  $\beta$-D-glucopyranose and $\alpha$-D-fructofuranose
• D

  $\alpha$-D-glucopyranose and $\beta$-D-fructopyranose

Solution

Sucrose is composed of $\alpha$-D-glucopyranose and a $\beta$-D-fructofuranose units which are joined by $\alpha, \beta$-glycosidic linkage between $\mathrm{C}-1$ of the glucose unit and C-2 of the fructose unit.

Hence, the correct answer is option: 'B'.