Welcome to the NCERT Solutions for Class 12 Biology - Chapter Human Health and Disease. This page offers a step-by-step solution to the specific question from Exercise 1, Question 12: . With detailed answers and explanations for each chapter, students can strengthen their understanding and prepare confidently for exams. Ideal for CBSE and other board students, this resource will simplify your study experience.
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Normal cell |
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Cancerous cell |
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1. |
Normal cells show the property of contact inhibition. Therefore, when these cells come into contact with other cells, they stop dividing. |
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Cancerous cells lack the property of contact inhibition. Therefore, they continue to divide, thereby forming a mass of cells or tumor. |
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2. |
They undergo differentiation after attaining a specific growth. |
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They do not undergo differentiation. |
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3. |
These cells remain confined at a particular location. |
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These cells do not remain confined at a particular location. They move into neighboring tissues and disturb its function. |
y B� �y0� ��� and T-lymphocytes.
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It does not have a specific memory.
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It is characterized by an immunological memory.
(b) Active and passive immunity
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Active immunity |
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Passive immunity |
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1. |
It is a type of acquired immunity in which the body produces its own antibodies against disease-causing antigens. |
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It is a type of acquired immunity in which readymade antibodies are transferred from one individual to another. |
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It has a long lasting effect. |
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It does not have long lasting effect. |
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It is slow. It takes time in producing antibodies and giving responses. |
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It is fast. It provides immediate relief. |
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Injecting microbes through vaccination inside the body is an example of active immunity. |
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Transfer of antibodies present in the mother’s milk to the infant is an example of passive immunity. |
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