Question

The nephridia in earthworm are analogous to
a. Gills of prawn
b. Trachea of insect
c. Nematoblasts of hydra
d. Flame cells of planaria

Answer 1

Analogous organs are those organs which have a different anatomically structured but perform similar functions. These result from the convergent evolution. Analogous organs have different origins.

Complete answer:
When you compare the anatomy and morphology of the organisms which are present today and those who existed years ago, they show some similarities and differences. These interpretations tell us whether common ancestors were shared or not. It is known as analogies and homologies.

Option A: Gills of prawns-
Gills are the primary respiratory organs in fishes. The gills allow the organisms to breathe underwater. The exchange of gases takes place through the gills in some of the fishes.

Option B: Trachea of insect-
The air enters through the external opening known as spiracles. These external openings give on to the trachea. The trachea is a densely networked array of tubes in the internal respiratory system. Trachea connects the larynx and bronchi. It is part of the respiratory system in an insect.

Option C: Nematoblasts of hydra-
The Nematoblasts produce nematocyst which is used for capturing and paralyzing the prey. It is also used for defensive purposes. Hydra has four kinds of nematocysts on their ectoderm and tentacles that are used for different purposes.

Option D: Flame cells of planaria-
Flame cells are found in freshwater invertebrates. It is the specialized type of excretory cells. It functions as a kidney and removes all the waste materials from the organisms.

The nephridia, unit of excretory system in many primitive invertebrates. It excretes out wastes from the body cavity to the exteriors. There are two forms simpler one, called protonephridia found in flatworms, rotifers, etc whereas complex one called metanephridia found in the earthworm, usually arranged in pairs.

Hence, the correct answer is option (D).

Note: Opposite to the analogous organs there is a homologous organ. The homologous organs are those organs which have the same anatomical structure but perform different functions. They are the result of the divergent evolution. It indicates the common ancestry.