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Question
Give reasons/explain:
During the starch test, the leaf is boiled in methylated spirit.
Solution
Boiling the leaf in methylated spirit removes chlorophyll, therefore it turns pale-white. The leaf is now brittle and stiff.
RELATED QUESTIONS
The diagram alongside refers to an experiment in which the apparatus was set up with the light source 10 cm away from the plant. After 15 minutes the number of bubbles evolved per minute from the cut stem was recorded. The light source was moved to 20 cm away from the plant, left for 15 minutes and the number of bubbles evolved per minute was again recorded. The experiment was repeated with the light source at distances of 40, 60, 80 and 100 cm away from the plant. Plot a graph for the results obtained and answer the following questions.
(i) From the graph it seems likely that the rate of bubbling per minute at 50 cm would have been
(a) 2.0 (b) 2.5 (c) 3.0 (d) 3.5
(ii) The gas produced by the plant during the experiment was
(a) air (b) oxygen (c) carbon dioxide (d) nitrogen (e) hydrogen
(iii) The gas collected comes due to the breakdown of
(a) glucose (b) starch (c) water (d) air (e) ATP
(iv) If ice cubes were added to the water, the rate of bubble formation would
(a) Stay the same.
(b) Increase because more water is added.
(c) Decrease because the temperature drops.
(d) Decrease because water freezes.
(e) Cannot tell from the information given.
(v) If some sodium bicarbonate is added to the water the rate of bubble formation
(a) Increases because more respiration occurs.
(b) Increases because more photosynthesis occurs.
(c) Increases because the gas becomes less soluble.
(d) Decreases because carbon dioxide acts as a limiting factor.
(e) Decreases because respiration decreases.
Why is it not possible to demonstrate respiration in a green plant kept in sunlight?
Given below is the representation of a certain phenomenon in nature. With four organisms 1-4.
- Name the phenomenon represented.
- Name any one organism that could be shown at No. 5.
- Name the biological process which was the starting point of the whole chain.
- Name one natural element which all the organisms 2-4 and even 5 are getting from No. 1 for their survival.
Given below is the representation of a certain phenomenon in nature. With four organisms 1-4.
Name the biological process which was the starting point of the whole chain.
Given alongside is the diagram of an experimental set-up:
Will it work satisfactorily? Given reason.
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
Why Is Photosynthesis Important in Nature?
Write the overall chemical equation for photosynthesis.
Given below is the figure of an experimental set-up, showing a physiological act of the plants. Study and answer the following questions:
- What is the objective of this experiment?
- Name and define the process shown here.
- Why do we destarch the leaves before performing the experiment?
- How do we destarch the leaves?
- What will be the observation when we pour iodine solution over the bleached experimental leaf?
- Write a well-balanced equation for the above process.
