UPSC Prelims 2006 Q147: Science & Technology – Health & Diseases
Consider the following statements:
1. ELISA test is employed as the first and most basic test for an individual to detect cancer.
2. Almost 50% of human beings have Rh+ blood while the remaining have Rh - blood.
Which of the statements given above is/are correct?
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer: (d) Neither 1 nor 2
Explanation
ELISA test and the Rh factor
| Statement | Verdict | Reason |
|---|---|---|
| 1. ELISA is the first and most basic test to detect cancer | False | ELISA is used to detect antibodies or antigens (e.g. HIV), not as the basic cancer screening test |
| 2. Almost 50% of human beings have Rh+ blood | False | About 85% of people are Rh-positive and about 15% Rh-negative |
Both statements are incorrect.
Answer: (d) Neither 1 nor 2.
Why each option is right or wrong
- (a) Incorrect. Statement 1 is false because ELISA is not the basic cancer-detection test.
- (b) Incorrect. Statement 2 is false because about 85% of people are Rh-positive.
- (c) Incorrect. Neither statement is correct.
- (d) CORRECT. ELISA is not the basic cancer test, and Rh+ blood is far more common than 50%.
Key point
ELISA is used mainly to detect infections like HIV, and about 85% of people are Rh-positive, so both statements are false.
Remember
ELISA is not the basic cancer test; about 85% of people are Rh+.
Common mistakes
- Linking ELISA with cancer screening rather than infection testing.
- Assuming Rh+ and Rh- are equally common.
- Mixing the Rh factor with ABO blood groups.
Exam tip
ELISA is best known for HIV antibody detection; Rh+ is about 85% of humans.
Sources
- NCERT Class XII Biology — Human Health and Disease
- National AIDS Control Organisation — HIV testing and diagnosis (ELISA)