Question

The excretory organs in earthworm are
A. Ureters
B. Stomata
C. Nephrons
D. Nephridia

Answer 1

Hint: The Phretima or earthworm has a well developed excretory system. They are made up of a large number of segmentally arranged, microscopic, coiled and glandular excretory tubules. They are unbranched with their inner ends opening into coelom by a funnel called nephrostome. They are found in small sizes in each segment in large numbers which are called micro nephridia and metanephridia.

Complete answer:
Option A- Ureter is a tubular organ through which urine passes from the kidney to the urinary bladder in humans.
Option B- Stomata are tiny openings in the epidermis of plant leaves which are responsible for the exchange of carbon dioxide and water.
Option C- The nephron is the basic structural and functional unit of the kidney found in humans.
Option D- These are excretory organs in earthworm which occur as coiled tubules arranged segmentally. Nephridia are ectodermal in origin. It occurs in all segments of the body except the first three.
It is of three types which are almost identical in structure
1. Septal nephritis - present on both sides of intersegmental septa of segment 15 to the last that opens into the intestine mainly responsible for water exchange or osmoregulation.
2. Integumentary nephritis - attached to the lining of the body wall of segment 7 to the last that open on the body surface, responsible for the exchange of nitrogenous waste to outer body surface pores.
3. Pharyngeal nephritis – present as three paired groups in 4,5 and 6 segments which help in filtering nitrogen from the surrounding capillaries.

Hence the correct answer is OPTION(D)

Note: A nephridium begins as a funnel that collects excess fluid from the coelomic chamber connected to the tubular part which transmits the waste through a pore to the surface in the body wall or digestive tube.