(a) What is translocation? Why is it essential for plants?
(b) Where do the substances in plants reach as a result of translocation?

Hint: Transportation in plants is the process by which movement of water and nutrients to various parts of the plants. Translocation is an example of mode of transportation.

Complete Answer:
Let us answer each question one by one.
(a) Translocation is the process of transport of nutrients such as sucrose and amino acids throughout the plant via the vasculature from their source of production to their location of storage.
It is an important process in plants because the source of production i.e., the location of photosynthesis is not the same as the site at which nutrients are stored; as a result it is essential that the nutrients be moved throughout the plant via translocation otherwise the food produced in the leaves will not be able to reach all parts of the plant.

(b) As a result of translocation, the food produced in the leaves reaches the roots, stem, fruits and other sites of storage in plants through the phloem which is a vascular tissue specialized for the transport of sucrose and other nutrients.

Additional information:
In plants, transportation occurs via three means,
1. Diffusion - It is a passive movement in which substances are transported from one cell to another or from one part of the plant to another. The substances move from a higher concentration to a lower concentration.
2. Active transport - It uses ATP to pump molecules against the concentration gradient.
Facilitate diffusion - It is a passive process which comprises uniport, symport and uniport.

Note: Similar to translocation, water and minerals are transported throughout the plant from the roots via the xylem. This process takes place against gravity opposite to the direction of translocation.