Question 1
Multiple choiceHard1 markA plant cell stores starch as represented in the figure. Each hexagon represents one α-glucose monomer; the diagram is schematic and not to scale. Which description correctly identifies P and Q and the structural basis of starch’s storage properties?
Show answer and explanation
Answer: C. In the figure, P joins separate α-glucose monomers into a starch polymer, while Q separates the polymer into monomers. Joining monomers by condensation releases water; hydrolysis uses water to break the polymer apart. Coiling and branching make the polymer compact, while its large molecular size makes it relatively insoluble.
A: reverses the direction of the two processes, so it assigns polymer breakdown to P and polymer building to Q.
B: identifies the processes correctly but reverses their water balance.
D: swaps the structural explanations: coiling and branching account for compactness, while large molecular size accounts for relative insolubility.
Remember: condensation builds glucose polymers and releases water; hydrolysis breaks them down and uses water.