Question

Colacal aperture is found in
A. Prototheria
B. Polychaeta
C. Primates
D. Protozoa

Answer 1

Hint: Cloacal aperture is the posterior orifice that serves as the only opening to the reproductive digestive and the excretory system.

Complete answer:
There are three groups under Animalia where mammals are divided.
Prototheria
Metatheria
Eutheria
> Prototheria: This is an oviparous mammal. The anatomy of Prototheria consists of a small corpus callosum which may be absent in some species. They do not have a marsupial pouch nor do they have nipples through which mammals generally feed their young ones. The reproductive system unlike humans, males have no scrotum, and in females placenta is absent. The digestive tract and urogenital tracts open into a cloaca which opens outside the body through the cloacal aperture.
> Metatheria: This is a viviparous mammal. The anatomy of Metatheria consists of a small corpus callosum which might be absent in a few species. They have a marsupial pouch where young ones are carried and kept warm in early developmental stages, abdominal nipples are present though which young one is fed during early stages. Their reproductive tract in males consists of a scrotum present in front of the penis and females have a less developed placenta. The anus and the urinogenital aperture opens in a shallow cloaca which has a common sphincter guarded opening.
> Eutheria: This is a viviparous mammal. The anatomy of Eutheria consists of a large and well-developed corpus callosum that connects the two hemispheres of the brain. The marsupial pouch is absent but abdominal or thoracic nipples are present for feeding the young ones. Males have a scrotum that is present behind the penis and females have a well-developed placenta. The digestive and urinogenital tract have separate openings

So, the correct answer is Prototheria.

Note: Colca is also present in Frogs which acts as a common passage for urine, sperm, and digestive waste, it opens outside the body through the cloacal aperture. The cloacal aperture helps expel waste from the body and stores/ holds sperms. Post fertilization eggs are also laid through the same cloacal aperture.