Home Preparation for National Talent Search Examination (NTSE)/ Olympiad
Chapter : 1. The cell
Plastids
Plastids : Introduction : • Plastids are organelles enclosed by a double membrane found in all plants. Historical Account : •E.Heckel (1865) gave the term plastid. Plastids are largest cell organelles. Ultrastructure : • Plastids occur in most plant cells and are absent in animal cells. • Plastids are self replicating organelles like mitochondria i.e. they have the power to divide. • Schimper divided plastids into three types : (a) Chromoplast - Coloured plastids (except green colour) (b) Chloroplast - Green coloured plastids (c) Leucoplast - Colourless plastid. • Plastids also have double membrane but no cristae. Functions of Plastids : • Chloroplasts trap solar energy and utilized it to manufacture food for the plant. • Chromoplast impart various colour of flower to attract insect for pollination.