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

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Solution

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.

Hence, the correct answer is option 1.

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Similar questions

Q. A potted plant was taken in order to prove a factor necessary for photosynthesis. The potted plant was kept in the dark for 24 hours. One of the leaves was covered with black paper in the centre. The potted plant was then placed in sunlight for a few hours.
During the starch test why was the leaf -
(1) boiled in water
(2) boiled in methylated spirit.

A potted plant was taken in order to prove a factor necessary for photosynthesis. The potted plant was kept in the dark for 24 hours. One of the leaves was covered with black paper in the centre. The potted plant was then placed in sunlight for a few hours.

(a) What aspect of photosynthesis was being tested ?

(b) Why was the plant placed in the dark before beginning the experiment ?

(1) boiled in water (2) boiled in methylated spirit.

(d) Write a balanced chemical equation to represent the process of photosynthesis.

(e) Draw a neat diagram of a chloroplast and label its parts.

Q. A destarched leaf on a potted plant was covered with Black (A) Transparent (B) strips of paper as shown in figure. After 6 hours of exposure to sunlight the leaf was removed from the plant and tested for starch. Which are the following will be the correct observation?

A candidate studied the importance of certain factors in photosynthesis. He took a potted plant and kept it in the dark for over 24 hours. In the early hours of the next morning, he covered one of the leaves with dark paper in the centre only. Then he placed the plant in sunlight for a few hours and tested the leaf which was covered with black paper for starch.

(a) What aspect of photosynthesis was being investigated ?

(b) Is there any control in this experiment ? If so, state it.

(d) Describe step by step, how the candidate proceeded to test leaf for the presence of starch.

Q. A star-shaped figure was cut in the black paper strip used for covering the leaf of a destarched plant used for demonstrating that light is necessary for photosynthesis. At the end of the experiment when the leaf was tested for starch with iodine, the star-shaped figure on the leaf was found to be:

(1) colourless
(2) green in colour
(3) brown in colour
(4) blue-black in colour

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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. Hence, the correct answer is option 1.

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.

Hence, the correct answer is option 1.