Question

A rootless aquatic plant in which a portion of the leaf is modified to form a bladder for catching small aquatic animals is
A. Dionaea
B. Drosera
C. Utricularia
D. Nepenthes

Answer 1

Plants are usually autotrophic but some of these feed on small insects or animals. Bladderworts are a genus of carnivorous plants. These plants occur in freshwater as aquatic species. They are cultivated for their flowers. They have bladder-like trap systems that help to capture small organisms.

Complete answer: The rootless aquatic plant named Utricularia that belongs to the genus bladderworts is a carnivorous aquatic plant. It is found growing in freshwater or wetlands. It bears small capturing bladder-like traps that capture small aquatic organisms. Minute protozoa and rotifers in water-saturated soils are prey to Utricularia. The traps range from $0.2$ mm to $1.2$ cm. Utricularia vulgaris which is the common bladderwort has larger bladders that feed on nematodes, water fleas, etc. The trapdoor consists of trigger hairs that entrap aquatic animals. The trap has negative pressure inside it when in the rest phase. When aquatic organisms trigger it mechanically they get sucked into it. The door of the trap closes when the bladder becomes full of water. This process occurs in a period of fifteen milliseconds. These plants are considered one of the most sophisticated structures of the Plant Kingdom. The bladder or the trap lies beneath the surface of the substrate over which the plant grows. The plant body has long and thin branching stems. The stems beneath the level of the substrate are called stolons. The bladder traps are attached to these stolons.
Therefore, option C is the correct answer.

Note: The flowers of Utricularia come in various colours. Their flowers resemble the snapdragon plant flowers. The flowers and the bladder trap together make Utricularia a very sophisticated species of the plant kingdom. The terrestrial species also bear traps. The unique trapping mechanisms make Utricularia have higher respiration rates.