Advertisements
Advertisements
Question
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.
Advertisements
Solution
(i) Destarched plant is the plant which lacks starch. Destarching is done by keeping the plant in dark for 2-3 days or covering a part of a leaf with a black paper by clip.
(ii) (a) The leaf is plucked and is boiled in water and decolourized with alcohol.
(b) The portion of leaf which received light turns blue with iodine because photosynthesis took place in that part of leaf.
(c) The part of leaf which was covered with black paper remains colourless because photosynthesis could not take place in the absence of sunlight.
This shows that starch is not manufactured in the absence of light.
APPEARS IN
RELATED QUESTIONS
Phosphate, RNA, Sugar, Nitrogenous base
Put a tick (✓ ) against the most appropriate alternative in the following statement.
Carbohydrates are stored by plants in the form of:
Describe an experiment to prove that sunlight is necessary for photosynthesis.
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.
In the flowering plants, food is transported in the form of ______.
Enumerate the steps involved in testing a green leaf for the presence of starch.
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.
The gas given out during photosynthesis is _____.
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?
______ food is made in their green stems.
