Question

The ascidian tadpole larva undergoes
A. Progressive metamorphosis
B. Retrogressive metamorphosis
C. Partial metamorphosis
D. Complete metamorphosis

Answer 1

Hint:
Ascidians are marine animals with a sac-like structure. During their development from a tadpole to an adult form, they lose some advanced features that were initially present during the initial stages of their life cycle. After metamorphosis, they possess only primitive features.

Complete answer:
The ascidian tadpole larva undergoes a retrogressive metamorphosis.
Retrogressive metamorphosis is a type of metamorphosis in which the free-swimming larva possessing advanced characteristics transforms into a sedentary adult with degenerative characteristics. So, on this type of metamorphosis, retrogression or degeneration is depicted by the larva while transforming into adults.

The correct answer is option ( B ) Retrogressive metamorphosis.

Additional information:
Metamorphosis is a biological process by which animals in their larval stages undergo certain morphological changes in the process of becoming an adult. These alterations can either change the entire body plan, a part of the body, the means of consuming food or breathing.
Let us have a look at the types of metamorphosis other than retrogressive.
Progressive metamorphosis
It is a type of metamorphosis in which the animal progresses in evolutionary grades during its development from a larva to an adult. The adult form possesses more advanced characteristics.
Partial metamorphosis
It is a type of metamorphosis in which only certain parts of the body undergo changes
Complete metamorphosis
It is a type of metamorphosis in which the entire body of an animal changes when it gets transformed into its adult form.

Note: Various animals undergo a metamorphosis during their life-cycle. The most famous example is that of a butterfly. It is born as a leaf-eating caterpillar, wraps itself in a cocoon for days, and comes out as a butterfly with wings, legs, exoskeleton, and a nectar sucking proboscis.