NCERT | Biology for JKSSB, JKPSC, UPSC , KUET PG Exams - Click on Link Below To download
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You might have noticed several small colored bodies in the cytoplasm of the cells of
Tradescantia leaf. They are scattered in the cytoplasm of the leaf cells. These are called
plastids.
• They are of different colours. Some of them contain green pigment called chlorophyll.
Green coloured plastids are called chloroplasts. They provide green colour to the leaves.
• Chloroplasts are important for photosynthesis in plants.
• Chloroplasts also contain various yellow or orange pigments in addition to chlorophyll.
• Plastids are present only in plant cells. There are two types of plastids – chromoplasts (coloured plastids) and leucoplasts(white or colourless plastids).
• Leucoplasts are primarily organelles in which materials such as starch, oils and protein
granules are stored.
• The internal organization of the plastids consists of numerous membrane layers embedded in a material called the stroma.
• Plastids are similar to mitochondria in external structure. Like the mitochondria, plastids also have their own dna and ribosomes.
