Question

why are plastids called kitchen of the cell

Answer 1

Plastids are known as kitchen of a cell because some kinds of plastids (chloroplasts) play a vital role in the process of photosynthesis in which plants make their own food by sunlight,water and nutrients.

Answer 2

They are the autonomous bodies present in a plant cell. They are so called because `chloroplast` a type of plastid has a green pigment called chlorophyll which anabolically produces food (Glucose) for the plant.

Anabolically comes from the word anabolic process which is a  a bioconstructive process.