PTE Multiple Choice, Single Answer practice

Pitcher plants employ passive pitfall traps lined with specialised microstructures to capture arthropods. The upper rim, or peristome, becomes exceptionally slippery when wet, as a thin film of water prevents insect footpads from making direct contact with the underlying surface. Once an insect loses its footing, it falls into a digestive pool below. In dry conditions, however, this lubricating layer evaporates, temporarily diminishing the trap's capture efficiency. Research indicates that this intermittent functionality may serve an adaptive purpose, allowing scout ants to return safely to their colonies and recruit larger cohorts before the trap reactivates.