Advertisements
Advertisements
Question
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.
Advertisements
Solution
(i) The student is investigating the necessity of sunlight for photosynthesis.
(ii) The leaf portion which is not covered with black paper is the control as it receives sunlight.
(iii) The plant is kept in the dark before the experiment to destarch the leaves.
(iv) The leaf is tested for the presence of starch as follows:
-
- The leaf is boiled with alcohol over a water bath till it becomes colourless.
- It is rinsed with hot water to remove alcohol and spread it on a white tile.
- Pour iodine solution on it. The portion covered with black paper remains colourless while the rest of the leaf turns blue-black.
APPEARS IN
RELATED QUESTIONS
The solvent used to dissolve the chlorophyll pigments while testing a leaf for starch is Soda lime.
Identify the false statements and rewrite them correctly by changing the first or last word only.
Starch produced in a leaf remains stored in it for 2-3 weeks before it is used by other parts of the plant.
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.
What is meant by a destarched plant? How can it be destarched?
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?
Name the following:
The chemical substance used to test the presence of starch in the cell of a leaf.
How does the light-dependent reaction differ from the light-independent reaction? What are the end product and reactants in each? Where does each reaction occur within the chloroplast?
The reactions of photosynthesis make up a biochemical pathway.
What is the end product of light and dark reactions of photosynthesis?
Name two raw materials for photosynthesis.
