Question

Cloaca is
(a)Common aperture for digestive and urinary systems
(b)Common aperture for digestive, urinary, and reproductive systems
(c)Common chamber in which reproductive, urinary, and digestive tracts open
(d)Common chamber for digestive and urinary tracts

Answer 1

Hint: Cloaca is a small opening present in all the amphibians, reptiles, birds, and a few mammals such as the prototherians. It is a common orifice to many systems of the body and opens to the outside as a small median orifice.

Complete answer:
Cloaca is a common aperture at the end of the digestive tract of an organism for the release of the excretory products but also serves as the opening for urine and the reproductive system. It is seen in vertebrates except for some fishes and most mammals) and certain invertebrates. The word is derived from the Latin verb “cluo” which means "to cleanse”.

Additional Information: In fishes, the true cloaca is only seen in sharks and rays and lobe-finned fishes. In most other fishes, there is a common opening for the urinary and reproductive system, but the anus is a separate opening.
In certain fishes like chimeras, all three openings are separate.
Most mammals do not have cloaca and have a separate aperture for the digestive system. However, some exceptions include the monotremes or the egg-laying mammals and marsupial mammals.
So, the correct answer is, “Common aperture for digestive, urinary and reproductive systems”

Note: -In some animals, cloaca can also have an accessory function in respiration.
-Some turtles that have specialized in diving, are highly reliant on cloacal respiration during dives. -They have a pair of accessory air bladders that are connected to the cloaca which absorb oxygen from the water.
-Some organisms like certain fishes and worms live in a commensal relationship with the sea cucumbers and take advantage of the cloacal respiration exhibited by them.