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Question
How would you demonstrate that green plants release oxygen when exposed to light?
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Solution
- Place some water plants (Elodea or Hydrilla) in a beaker containing pond water and cover them by a short-stemmed funnel.
- Invert a test tube full of water over the stem of the funnel. (Ensure that the level of water in the beaker is above the level of the stem of the inverted funnel.)
- Place the apparatus in the sun for a few hours (in Fig). Bubbles of the gas will collect in the test tube.
- Test the gas in the test tube. A glowing splinter bursts into flame, which shows the presence of oxygen.
RELATED QUESTIONS
Two healthy green plants were placed in the dark for 24 hours. They were then set up, as shown in the figure, for 4 hours. Then a leaf was taken from each plant and
the chlorophyll was removed from the leaves:
( i) What is the next and final step in this experiment?
( ii ) What would be the results of the final step?
( iii ) Why was it necessary to grease the glass sheet?
( iv ) What hypothesis is being tested in this experiment?
Name the following:
The main mineral constituent of chlorophyll.
Mention one difference between the following on the basis of what is given in bracket.
Chlorophyll and chloroplast (part of plant cell)
The chemical substance used to test the presence of starch in the cell of a leaf is ______.
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 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 alteration (s) will you make in it for obtaining expected result?
Given alongside is the diagram of an experimental set-up:
Would you take any step before starting the experiment? Describe this step and explain its necessity.
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
Give reasons/explain:
During the starch test, the leaf is boiled in methylated spirit.
