Question

How many of the following are incorrectly matched pair(s):

	Column I	Column II
1	Detection of infection	By detecting the presence of antigen or antibodies produced against it
2	Conventional methods for diagnosis of disease	Early diagnosis and reliable method
3	PCR	Detects HIV in suspected AIDS patients

• A. 1 only
• B. 1 and 2 only
• C. 2 and 3 only
• D. 1, 2 and 3

Answer 1

The correct option is A 1 only

Biotechnology has proven useful in early diagnosis of a disease.

Pair 1 is correct: The disease can be detected either by testing for the presence of an antigen (proteins, glycoproteins, etc.) in the sample or for the presence of antibodies produced against it. For e.g.: ELISA (enzyme-linked immunosorbent assay) detects the presence of antibodies synthesised against the pathogen. ELISA works on the principle of antibody-antigen interaction.

Pair 2 is incorrect: The process of studying the symptoms in a person as a result of a disease is called diagnosis. The diagnosis can either occur through a physical examination or by reading briefly through the medical history of the patient. In some cases, tests are carried out to discover the underlying cause of a disease. Early diagnosis of disease is important so that before the pathogen increases its count and starts affecting the body adversely one can be treated well. But conventional methods (like urine analysis) of diagnosis may not allow early detection as the degree of infection might be less and hence the test result may not be reliable.

Pair 3 is correct: (Polymerase chain reaction) is a technique used in molecular biology to create several copies of a certain DNA segment. In PCR, a short segment of DNA is amplified using primer-mediated enzymes.
Very low concentration of pathogens can be detected by PCR. PCR is used to detect pathogens like HIV in suspected AIDS patients. This test finds either the RNA of the HIV virus or the HIV DNA in leucocytes infected with the virus.