Question

In phloem transport, the source-sink relationship is variable. Identify the statements in support of this.

• A. Food is primarily transported as sources through phloem
• B. Sugar stored in roots may be mobilized to buds in early spring
• C. The direction of movement in phloem can be upwards on down wards i.e., bidirectional
• D. Both b & c

Answer 1

The correct option is D

Both b & c

Food is transported through phloem from the source to the sink. Food is synthesized in the leaves, which acts as the source, and it is transported to roots, which act as the sink. Source and sink may be reversed. Depending on the season or the plant's requirements, the sugar stored in the roots may be mobilized to other parts; like from roots to buds during the spring season. Therefore direction of movement of food materials in phloem is bidirectional based on the need of the plant.