Question

phloem vessels is comparad with the two way traffic road

Answer 1

Phloem transport is bidirectional, since the requirement of food in a plant is both ways(roots and shoots both), so food is transported downwards as well as upwards and hence this is an active process consuming energy.

Also the source-sink relationship between roots and shoots varies with seasons:

For example,

→ in winters,lack of sunlight means little to none photosynthesis, so leaves need food, here roots act as source and transport the food(which was stored in the roots) upwards.

→ in summers, ample sunlight means proper photosynthesis and here leaves become the source and transport food to the roots in the downward direction and shoot in the upward direction.

Answer 2

Phloem transport is bidirectional, since the requirement of food in a plant is both ways(roots and shoots both), so food is transported downwards as well as upwards and hence this is an active process consuming energy.

Also the source-sink relationship between roots and shoots varies with seasons:

For example,

→ in winters,lack of sunlight means little to none photosynthesis, so leaves need food, here roots act as source and transport the food(which was stored in the roots) upwards.

→ in summers, ample sunlight means proper photosynthesis and here leaves become the source and transport food to the roots in the downward direction and shoot in the upward direction.