The steps taken for setting up an experiment to demonstrate that ‘light is necessary for photosynthesis’, were as follows
• A strip of black paper was clipped on the leaf of a potted plant
• The plant was kept in the sun for four hours
• The strip was removed and the leaf was placed in boiling alcohol in water bath
• The leaf was washed and tested for starch
The result was not as expected. Identify the step which had been missed out .
(1) The plant was kept in the dark for 24 hours before starting the experiment
(2) The leaf was boiled in water after placing it in boiling alcohol
(3) The leaf was sprinkled with water before placing it in black paper strip
(4) A transparent strip was used to cover the black paper strip
Correct answer: (1) The plant was kept in the dark for 24 hours before starting the experiment
Explanation:
In the above experiment, the step which requires to keep the plant in dark for 24 hrs was missing before starting the experiment.
It is important to keep the plant in dark before starting the experiment so that all the leafs can be destarched.