The correct option is Both A and R are true but R is NOT the correct explanation of A.
Explanation
Living organisms are highly organized structures. To maintain this order against the natural tendency towards disorder (entropy), they require continuous repair and maintenance. These maintenance processes occur through invisible molecular movements (such as diffusion, active transport, and metabolic reactions), which are fundamental to the definition of life.
Statement-wise Analysis
- Assertion (A): Correct
Visible physical growth or locomotion is not a defining characteristic of life because many organisms, such as plants, do not exhibit visible locomotion yet are alive. However, invisible molecular movements are absolutely necessary for existence to perform vital functions like nutrition, respiration, and cellular repair. - Reason (R): Correct
Viruses are acellular entities that lack independent metabolic machinery. They do not exhibit any molecular movement or life processes (like reproduction or energy production) while outside a host body. They only display molecular activity after infecting a host cell.
Justification for Both A and R are true but R is NOT the correct explanation of A
While the Reason (R) provides a valid example (viruses) that highlights the link between molecular movement and the definition of life, it does not explain the fundamental biological cause stated in the Assertion. The necessity of invisible molecular movements (A) is due to the requirement of maintaining structural order and preventing breakdown, not merely because viruses lack them.
Key Takeaway:
Molecular movement is a defining characteristic of life essential for maintaining living structures. Viruses are considered borderline between living and non-living because they lack independent molecular movements.