RAS question
Biosensors combine:
Correct answer: (A) A biological recognition element with a physical transducer.
Biosensors combine a biological recognition element that gives analyte specificity with a physical transducer that converts the biological response into a measurable signal.
Explanation
A biosensor is not just a biological test material and not just an electronic detector. Its defining design is the pairing of a biorecognition element with a transducer. The biological element, such as an enzyme, antibody, DNA or cell, recognises the target analyte and gives the sensor specificity. The transducer then turns that biological response into a measurable output, for example through electrochemical, optical or thermal signal conversion. This is why familiar devices such as glucose meters, pregnancy tests and COVID rapid tests are treated as biosensor applications: the biology identifies the target, while the transducer or detection system makes the result readable.
Why the other options are wrong
- (B) Two magnets do not provide a biological recognition element for a target analyte or a transducer that converts that recognition into a quantifiable signal.
- (C) Light and sound are physical phenomena, but the biosensor definition requires a biological recognition element paired with a transducer, not simply two signal types.
- (D) Two chemicals alone do not explain the specific biological recognition step and the measurable signal-conversion step that define a biosensor.
Concept
This tests the Science and Technology concept of sensor architecture: recognition, transduction and readable output. It recurs in RAS because biotechnology in public health diagnostics is often framed through practical devices rather than pure theory.