State the covalent bond that links the two monomers in sucrose.
In the human digestive system, sucrose is hydrolysed by the enzyme sucrase. This reaction produces the monosaccharides $\alpha$-glucose and fructose. Finish the diagram to show sucrose being hydrolysed to give $\alpha$-glucose and fructose.
State the name of the structure labelled X in Fig. 4.2.
A scientist investigated carbohydrate transport in the stem of a woody plant. Fig. 4.3 is a plan diagram of a transverse section of the stem studied by the scientist, showing where the xylem tissue is located. For each experiment, a ring of tissue was removed from the outside of the stem, while the xylem tissue was kept intact, as shown in Fig. 4.4. The mass of carbohydrate transported to the lower part of the stem in 24 hours was measured. Each time, a different percentage of the outer stem tissue was removed. Every other variable was kept constant. Table 4.1 gives the results of this investigation. Explain the results shown in Table 4.1.
Suggest and explain why a person with this deletion mutation is unable to digest sucrose.