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प्रश्न
Enumerate the steps involved in testing a green leaf for the presence of starch.
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.
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संबंधित प्रश्न
ATP [Expand the abbreviation]
State the main function of the Lenticels
Put a tick (✓ ) against the most appropriate alternative in the following statement.
Which one of the following is an end-product of photosynthesis?
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?
A healthy croton plant bearing variegated leaves was kept in a dark cupboard to destarch it after which it was placed in sunlight for a few hours. One of the leaves was then plucked and an outline of the leaf marking the green and the non-green regions was drawn. The leaf was then tested for starch. Using the above information, answer the following questions:
- State the aim of the above experiment.
- Name the chemical used for testing the presence of starch.
- Why is the leaf boiled in water and alcohol before testing for the presence of starch?
- What change is seen on the leaf after the starch test?
- Give the chemical equation to represent the process of starch formation in plants.
Name the following:
In-plant cells, carbohydrates are stored in which form.
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?
