Title Photosynthesis-in-Higher-Plants.pdf ✅

1. Photosynthesis in Higher Plants Photosynthesis in Higher Plants INTRODUCTION y Green plants and some chlorophyll bearing bacteria are autotrophic and synthesise organic compounds by using simple inorganic compounds in the presence of sunlight. y All the heterotrophic organisms are dependent on the food prepared by autotrophs for survival. y All life forms on earth are dependent on sunlight for energy directly or indirectly. y Thus, the use of energy from sunlight by the plants to do photosynthesis is the basis of life on earth. SIMPLE EXPERIMENTS RELATED TO PHOTOSYNTHESIS y Photosynthesis occurs in green parts of the plants in the presence of sunlight and starch is manufactured after the process. It can be demonstrated as follows: ○ A small potted plant is placed in dark for 72 hours to get its leaves destarched. Definition Photosynthesis: It is a physico-chemical (anabolic) process by which plants and certain other organisms use light energy and synthesise their own organic food. Previous Year’s Question Chlorophyll a is found in all (1) O2 liberating photosynthetic organisms (2) Autotrophs (3) Higher plants (4) Algae


Photosynthesis in Higher Plants 4. y Thus, he showed that only the green parts of the plants could release oxygen. Julius von Sachs y He showed that the green substance (chlorophyll) is located in special bodies (chloroplasts). y He provided evidence (1854) for the production of glucose when plants grow and glucose is stored in the form of starch. y He found that green parts of the plants are the places where glucose is made. T. W. Engelmann (1843–1909) y He split the light causing a prism into its component parts and illuminated a green alga, Cladophora placed in suspension of aerobic bacteria. Previous Year’s Question Water soluble pigments found in plant cell vacuoles are (1) carotenoids (2) anthocyanins (3) xanthophylls (4) chlorophylls Definitions Photosynthetic Pigments: Pigments that absorb light of certain wavelength(s) of the visible spectrum. Accessory Photosynthetic Pigments: These are the pigments which absorb light energy and pass it on to the main photosynthetic pigments, but do not carry out the reactions themselves. Previous Year’s Question Which pigment absorbs the red and far red light? (1) Cytochrome (2) Phytochrome (3) Carotenoids (4) Chlorophyll