Question

Which of the following is called a sugar sink?
A. Roots
B. Developing seeds
C. Both A and B
D. Leaves

Answer 1

Hint: Leaves are the sugar sources of the plant and roots are the sugar sinks of the plant. Sinks are those parts which store the sugar.

Complete Answer: Plant has xylem and phloem as conducting tissues which transport sugar molecules in the form of sucrose. The sugar molecules are transported from source end to sink end. Plant is divided into source and sink. Sinks are the sites where it is stored or used. Plants include both source and sink parts. Sources are the parts where net fixation of carbon dioxide occurs.
The correct answer is C. Both A and B.

Additional Information: It is a longer distance movement of organic substances from the source or supply end to the region of utilization or sink. But the source and sink may be reversed depending on the season or need of the plant. Sugar stored in roots may be metabolized to become a source of food in the early spring when the buds of trees act as a sink and require energy for their growth and development. Since the source-sink relationship is variable, the direction of movement of organic solutes in phloem can be bidirectional that is upwards or downwards and in case of xylem, it is unidirectional. Translocation is directional movement of materials which occurs inside vascular tissues (Xylem and Phloem).

Note: Roots and developing seeds both act as sugar sink. The sugar is stored in the form of energy in roots which are acting as sinks.