In this section each item consists of six sentences of a passage. The first and sixth sentences are given in the beginning as S1 and S6. The middle four sentences in each have been jumbled up and labelled as P, Q, R and S. You are required to find the proper sequence of the four sentences and mark your response accordingly on the answer sheet.
S1 : Mutations are random changes to the base sequence of genes.
S6 : Several mutations must occur in the same cell for it to become a tumour cell.
P : This is why mutations in them can result in uncontrolled cell division and therefore tumour formation.
Q : The few genes that can become cancer-causing after mutating are known as oncogenes.
R : Most genes do not cause cancer if they mutate.
S : In a normal cell oncogenes are involved in the control of cell cycle and cell division.
The correct sequence should be
- ARQSP
- BQRSP
- CQSRP
- DRPQS
Explanation
S1 introduces mutations as random changes. R states most genes don't cause cancer when mutated, which logically follows S1. Q then introduces the exception: the few genes (oncogenes) that can cause cancer. S defines oncogenes' normal role in cell cycle control. P explains why mutations in oncogenes cause uncontrolled division. This leads to S6 about multiple mutations needed. The sequence R-Q-S-P flows from general (most genes safe) to specific (oncogenes) to mechanism. Option (a) RQSP is correct. Cross-checked with Oswaal CDS Yearwise Solved Papers.