Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Metastasis is the most feared property of malignant tumours.
Reason (R): The cells of malignant tumours starve the normal cells by competing for vital nutrients.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Both (A) and (R) are true but (R) is not the correct explanation of (A).
Assertion (A): Metastasis is the most feared property of malignant tumours. — True. A is about why malignant tumours are feared. Cells sloughed from a malignant tumour reach distant sites through the blood and start new tumours wherever they lodge. This spread is called metastasis.
Reason (R): The cells of malignant tumours starve the normal cells by competing for vital nutrients. — True. R is about what tumour cells do to their neighbours. As they actively divide and grow, they compete with the normal cells for nutrients and starve them.
Why R does not explain A? R describes damage done at the place where the tumour grows. Metastasis is something else: the spread of tumour cells through the blood to distant parts of the body, where new tumours form. Starving nearby cells does not make a tumour spread, so R cannot be the reason metastasis is feared. So both statements are correct, but R is not the explanation of A.
NCERT Extract:
Cancer – “… The malignant tumors, on the other hand are a mass of proliferating cells called neoplastic or tumor cells. These cells grow very rapidly, invading and damaging the surrounding normal tissues. As these cells actively divide and grow they also starve the normal cells by competing for vital nutrients. Cells sloughed from such tumors reach distant sites through blood, and wherever they get lodged in the body, they start a new tumor there. This property called metastasis is the most feared property of malignant tumors.”