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प्रश्न
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
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उत्तर
(1) The leaf was boiled in water to destroy enzymes so that further chemical changes do not take place in the leaf.
(2) The leaf was boiled in methylated spirit to dissolve chlorophyll.
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संबंधित प्रश्न
An experiment was set up as shown in the figure given below . The twig in the diagram was intact on the plant and it was as such in sunlight for a few hours .
(i) What is the aim of the above experiment ?
(ii) Why was potassium hydroxide placed inside the conical flask ?
(iii) What test would you perform on the leaf inside the flask?
(iv) What is the expected result of the above test ?
(v) Is it necessary to similarly test on outer leaf also ? Giva a reason .
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.
Are the following statement true or false? Give a reason in support of your answer.
Destarching of the leaves of a potted plant can occur only at night.
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 alongside is the diagram of an experimental set-up:
- What is the objective of this experiment?
- Will it work satisfactorily? Give reason.
- What alteration(s) will you make in it for obtaining expected result?
- Would you take any steps before starting the experiment? Describe this step and explain its necessity.
Why Is Photosynthesis Important in Nature?
Give technical term:
Name only one plant, you are familiar with which has no chlorophyll.
Give technical term:
Name the experiment to demonstrate the importance of light for photosynthesis.
Given below is the diagram of an experimental set-up (final stage). Study the same and answer the following questions:
- What is the main aim of the experiment?
- Oxygen gas shown in the experiment is released from which of the raw materials?
- How would you confirm the presence of oxygen gas?
- Name the chemical substance which can be added in water to enhance the process/rate of release of oxygen gas.
- Draw a neat and labelled diagram of the same experiment for its initial stage.
