Question

Plastids are present only in plant cells. Why?

Answer 1

Because the work of Plastids to give green colour to plant.It is responsible for photosynthesis in plants.
Therefore,there is no need of such an organ in animal cell as animals does not take part in photosynthesis.

Answer 2

Plastids are only present in plant cells because -

• The chemical compounds synthesized by the plastids, are only necessary for the different biological activities of the plant body.
• There are colour defining pigments present in the plastids. Now, the animal bodies don't need such colour defining pigments.
• The plastids contain chloroplast which can help in the occurrence of photosynthesis. Now, the animal bodies do not need the help of the photosynthesis process for making it's necessary food materials.
• For the above mentioned reasons, the plastids are only present in plant cells.