(b) Phaeoplasts (pheo = brown) : These are brown plastids containing xanthophylls and fucoxanthin. These are ditfly present in brown algae (Phaeophyceae).
(c) Rhodoplasts (Rhodo = red) : These are red coloured plastids, containing phycoerythrin, Iycopene (as in tomato). These are chiefly present in red algae (Rhodophyceae).
CHLOROPLAST (Green plastids)
These are the most common plastids and found in almost all autotrophs. Most of the photosynthesis by a plant is caried out by chloroplasts. Chloroplasts were discovered by Leeuwenhoek.
Shape and number
- Chloroplasts are ovoid, spherical or disc shaped structures. However in algae they can exist in many shapes ( cup shaped in Chlamydomonas, girdle shaped in Ulothrix, Spiral shaped in Spirogyra, star shaped in Zygonema and reticulate in Dedogonium).
- Number of chloroplasts may vary in different kinds of cells. In many algae there is a single chloroplast per cell but in either cells this number is usually 20 to 40 per cell. The leaf of Ricinus communis contains about 400,000 chloroplasts per square mm of surface area.
Structure of chloroplast
There are three main components in the chloroplast - envelope, stroma and grana (thylakoid).
1. Envelope
- The envelope of chloroplast consists of a double walled limiting membrane. Both walls of the envelope are smooth and do not show any folding.

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Question Text	(b) Phaeoplasts (pheo = brown) : These are brown plastids containing xanthophylls and fucoxanthin. These are ditfly present in brown algae (Phaeophyceae). (c) Rhodoplasts (Rhodo $=$ red) : These are red coloured plastids, containing phycoerythrin, Iycopene (as in tomato). These are chiefly present in red algae (Rhodophyceae). CHLOROPLAST (Green plastids) These are the most common plastids and found in almost all autotrophs. Most of the photosynthesis by a plant is caried out by chloroplasts. Chloroplasts were discovered by Leeuwenhoek. Shape and number - Chloroplasts are ovoid, spherical or disc shaped structures. However in algae they can exist in many shapes ( cup shaped in Chlamydomonas, girdle shaped in Ulothrix, Spiral shaped in Spirogyra, star shaped in Zygonema and reticulate in Dedogonium). - Number of chloroplasts may vary in different kinds of cells. In many algae there is a single chloroplast per cell but in either cells this number is usually 20 to 40 per cell. The leaf of Ricinus communis contains about 400,000 chloroplasts per square $mm$ of surface area. Structure of chloroplast There are three main components in the chloroplast - envelope, stroma and grana (thylakoid). 1. Envelope - The envelope of chloroplast consists of a double walled limiting membrane. Both walls of the envelope are smooth and do not show any folding.
Updated On	Jan 2, 2023
Topic	Cell: Structure and Functions
Subject	Biology
Class	Class 11
Answer Type	Video solution: 1
Upvotes	66
Avg. Video Duration	3 min

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