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Class 12
Zoology :-NCERT Solutions - Human Health and Diseases

Question 12
How is a cancerous cell different from a normal cell?


Answer:

Answer

 

Normal cell

 

Cancerous cell

1.

Normal cells show the property of contact inhibition. Therefore, when these cells come into contact with other cells, they stop dividing.

1

Cancerous cells lack the property of contact inhibition. Therefore, they continue to divide, thereby forming a mass of cells or tumor.

2.

They undergo differentiation after attaining a specific growth.

2.

They do not undergo differentiation.

3.

These cells remain confined at a particular location.

3

These cells do not remain confined at a particular location. They move into neighboring tissues and disturb its function.


(b) Active and passive immunity

 

Active immunity

 

Passive immunity

1.

It is a type of acquired immunity in which the body produces its own antibodies against disease-causing antigens.

1.

It is a type of acquired immunity in which readymade antibodies are transferred from one individual to another.

2.

It has a long lasting effect.

2.

It does not have long lasting effect.

3.

It is slow. It takes time in producing antibodies and giving responses.

3.

It is fast. It provides immediate relief.

4.

Injecting microbes through vaccination inside the body is an example of active immunity.

4.

Transfer of antibodies present in the mother’s milk to the infant is an example of passive immunity.