Question

What are plastids ? name the two types of plastid and explain them. and..... what is the difference between chloroplast and chromplast.

Answer 1

Plastids are double membraned organelles which are found in plant cells only. They are usually spherical or discoldal in shape and their average size is 4 to 6 um. A plastid shows tow distinct regions-grana and stroma Grana are stacks of membrane-bound, flattened, discold sacs containing chlorophyll molecules. These molecules are responsible for the production of food by the process of photosynthesis. They are, therefore, called Kitchen of the cell. Plastids are of three types:

1. Leucoplasts are colorless plastids. They store the food of the plant body in the form of starch, protein and lipids. They occur most commonly in the storage cells of roots and underground stems.

2. Chloroplasts are green plastids because of the presence of chlorophyll. Chloroplasts occur abundantly in green leaves, and also to some extent in green parts of the shoot.

3. Chromoplasts are variously colored plastids. They are mostly present tin flowers and fruits.

Differance
The term "chromoplast" is occasionally used to include any plastid that has pigment, mostly to emphasize the difference betweenthem and the various types of leucoplasts, plastids that have no pigments. In this sense, chloroplasts are a specific type ofchromoplast.