Question

Which of the following animal is unisexual?
a. Tapeworm
b. Leech
c. Sponge
d. Earthworm
e. None of these

Answer 1

Hint: The organisms in which male and female reproductive system are present in different individuals are called as Unisexual organisms or dioecious .For example: Human beings, birds, reptiles, fish etc.

Complete answer:
> Tapeworm: Tapeworms belong to phylum Platyhelminthes; a group of parasitic flatworms. They absorb their nutrition from their host directly through their body surface. The sexes are not separate, that is they are bisexual and reproduce from self-fertilization. Examples are liver fluke and planaria.

> Leech and Earthworm: Leeches and earthworms are members of phylum annelida; it is thought that annelids are animals with two separate sexes i.e. they are unisexual. These can reproduce asexually as well, by dividing into two or more pieces or by budding off a new individual while the parent remains a complete organism. In contrast, both leeches and earthworms are exceptions. These are monoecious or bisexual i.e. these have both the male and female reproductive organs in the same individual.

> Sponge: Members of phylum porifera are commonly called sponges. These organisms do not have separate sexes i.e. these are bisexual. Some examples of sponges are sycon, spongilla.

Since, all the organisms given in the question are bisexual, i.e. none of these organisms is unisexual.
Hence, the correct answer is option (E).

Note: The organisms in which the male and the female reproductive system are present in the same individual are called as bisexual organisms. These organisms are also known as hermaphrodites.