how can you show that chlorophyll is essential for photosynthesis
Answers
Observation : The blue colour appears only in those parts of leaf which were green in colour. The blue colour will not appear in variegated parts. This shows that starch formation takes place only in green (chlorophyll containing) parts of the leaf. Thus, the chlorophyll is essential for photosynthesis.
Answer:
To demonstrate that chlorophyll is essential for photosynthesis.
Requirements : A potted plant with variegated leaves - for example, Croton or money plant (variegated leaves are partly green and partly white), rice paper, pencil, white paper sheath, beaker, test tube, 70% alcohol, KL solution, water bath.
Explanation:
Method : Keep the potted plant with variegated leaves in dark for three days so that the leaves become free from starch. Then place the plant in bright sun light for about 6 hours. Take a variegated leaf of the potted plant kept in bright sunlight. Trace the outline of leaves and its variegated parts on the tracing paper (the variegated leaves show pale yellow spots in green leaves. These areas indicate the absence of chlorophyll). Dip the leaf in boiling water for a few minute. Now boil the leaf in 70% alcohol till it decolorizes. Now dip the leaf in boiled water to make the leaf soft. Take out the leaf and stain with iodine (KL) solution. Observe the change in colour.
Observation : The blue colour appears only in those parts of leaf which were green in colour. The blue colour will not appear in variegated parts. This shows that starch formation takes place only in green (chlorophyll containing) parts of the leaf. Thus, the chlorophyll is essential for photosynthesis.
other acivity
@ Take a potted plant with variegated leaves like money plants or cotton.A variegated leaf has patches of photosynthetic areas.
@ Destarch the plant by keeping it in a dark room for three days.
@ Now place the plant in sunlight for six hours.
@ Detach a leaf from the plant and on a paper make its sketch.Carefully mark the distribution of chlorophyll in the leaf.
@ Dip the leaf in boiling water to denature the enzymes present in the cells of the leaf and to make cell-membrane permeable.
@ After this,immerse it in a beaker containing alcohol.It is used for removing the chlorophyll pigments from the cells of the leaf.
@ Carefully place the above beaker in a water-bath and heat till the alcohol begins to boil As alcohol is highly flammable,it can catch fire if boiled directly on a flame.
@ The chlorophyll pigments dissolve in alcohol,so solution becomes dark in colour while the leaf loses its green colour.
@ Now dip the leaf in a dilute solution of iodine for few minutes to test the presence of starch.
@ Take out the leaf and rinse off iodine solution and observe the colour of the leaf and compare this with tracing of leaf done in the beginning.
Explanation:You will observe that the areas containing chlorophyll pigments show blue-black colour due to the presence of starch.Carbohydrates produced during photosynthesis are stored as starch in the cells.So it can be inferred that chlorophyll is necessary for photosynthesis.
(Note - @ = Point)