Table of Contents

Class VII – Science

Chapter 1: Nutrition in Plants

Identify X and state its function.
Answer: X is a stomata. Its function is to allow gas exchange (oxygen and carbon dioxide) and regulate water loss through transpiration.
A. Why do we need to keep the plant in dark for 2-3 days?
Answer: To ensure that all the starch is used up, making it easier to observe the formation of new starch during the experiment.
B. Why do we need to boil the leaf in alcohol?
Answer: To remove the chlorophyll, which makes the leaf colorless and easier to see the color change when iodine is added.
C. What is the process of decolorizing a leaf known as?
Answer: The process is known as bleaching.
D. Why does the uncovered part turn blue-black whereas the covered part does not?
Answer: The uncovered part of the leaf turns blue-black because it has been exposed to sunlight and has produced starch. The covered part does not turn blue-black because it did not receive sunlight and therefore did not produce starch.
E. What can we conclude from the above experiment?
Answer: The experiment demonstrates that sunlight is necessary for photosynthesis, which produces starch in the leaves.
What are these white, green, or brown patches of thread-like growth X known as?
Answer: These patches are known as fungi.

A. What are these swollen structures known as?
Answer: These swollen structures are known as root nodules.
B. Name the bacteria that is found in these root nodules? Mention its significance.
Answer: The bacteria found in these root nodules is Rhizobium. Its significance is that it helps in nitrogen fixation, converting atmospheric nitrogen into a form that plants can use.
Identify the parts X and Y. What is the special name given to these plants?
Answer: Part X is the lid of the pitcher plant, and part Y is the pitcher. These plants are known as insectivorous plants.

What is the relationship exhibited by plants X and Y known as?
Answer: The relationship is known as symbiosis.
Give another example of this type of relationship.
Answer: Another example of symbiosis is the relationship between lichen (algae and fungus).