Advertisements
Advertisements
प्रश्न
Enumerate the steps involved in testing a green leaf for the presence of starch.
Advertisements
उत्तर
Test to determine the presence of starch in a leaf:
- Dip a leaf in boiling water for a minute to kill the cells.
- Boil the leaf in methylated spirit in a water bath to remove the chlorophyll, till the leaf turns pale blue and becomes hard and brittle.
- Now place the leaf in hot water to soften it.
- Place the leaf in a Petri dish and pour iodine solution over it.
- The appearance of a blue-black colour on the leaf is indicative of the presence of starch.
- The absence of starch is indicated by a brown colouration.
संबंधित प्रश्न
The solvent used to dissolve the chlorophyll pigments while testing a leaf for starch is Soda lime.
(i) Fill in the blanks in the following equations of two chemical reactions:
(a) \[\ce{---+12H2O->[Light energy]C6H12O6 + --- + ----}\]
(b) \[\ce{--- 6O2->[Chlorophyll] 6 --- +6 ---- + Energy}\]
(ii) Name the two processes represented by the above two reactions.
(iii) State any two differences in these processes other than those already indicated in the reactions.
(iv) Which one of these two reactions is the supporter of all life on earth?
A potted destarched plant was taken in order to prove that light is necessary for photosynthesis.
(i) What is meant by 'destarched plant'? How can it be destarched?
(ii) Using the destarched plant describe step by step how you would proceed to prove that in the absence of light the leaf cannot manufacture starch.
In the flowering plants, food is transported in the form of ______.
A leaf is a food factory. Explain.
On a bright sunny day, water weeds growing in an aquarium were actively giving off bubbles of gas. Use this information to answer questions that follow:
- Name the process occurring in the water weed that has resulted in the evolution of these bubbles.
- Of what gas do these bubbles consist?
- Briefly describe the reactions occurring in the leaves of the water weeds leading to the evolution of these bubbles.
- Give an overall balanced chemical equation to represent the process named in (i) above.
Using the destarched plant describe step by step how would you proceed to prove that in the absence of light the leaf cannot manufacture starch?
A candidate in order to study the importance of certain factors in photosynthesis took a potted plant and kept it in the dark for over 24 hours. Then in the early hours of the morning, she covered one of the leaves with black paper in the center only. She placed the potted plant in the sunlight for a few hours, and then tested the leaf which was covered with black paper for starch.
- What aspect of photosynthesis was being investigated?
- Is there any control in this experiment? If so, state the same.
- Why was the plant kept in the dark before the experiment?
- Describe step by step how the candidate proceeded to test the leaf for the presence of starch.
State whether true or false. If false, correct the statement.
Photosynthesis produces glucose and carbon dioxide.
The reactions of photosynthesis make up a biochemical pathway.
What is the end product of light and dark reactions of photosynthesis?
