Question

Function of allantois is
A) Respiration
B) Excretion
C) Nutrition and excretion
D) Protection from shock

Answer 1

Allantois is the extra-embryonic membrane of reptiles, birds and mammals which arises as a pouch, sac from the hindgut.

Complete answer:
Allantois:-

The allantois is a hollow sac-like structure.
It is filled with a clear fluid that forms the part of a developing amniote’s conceptus.
The allantois is primarily involved in nutrition and excretion and is webbed with blood vessels.
The function of allantois is to collect liquid waste from the embryo and to exchange gases used by the embryo.
Functions of allantois in different animals:
In reptiles, and birds : The structure allantois was first evolved in reptiles and fishes as a reservoir for nitrogenous waste and also a means for oxygenation of the embryo. Oxygen is absorbed through the egg cell by the allantois.
In marsupials : In marsupials the allantois store nitrogenous waste. In these animals the allantois is avascular, and has no blood vessels. Most of the allantois do not fuse with chorion in marsupials except bandicoots.
In placental mammals : In placental mammals allantois become the part of the umbilical cord. The human allantois is a caudal outpouching of the yolk sac which is surrounded by the mesodermal connecting stalk called as the body-stalk.
Therefore, it has been clear from the above discussion that the function of allantois is nutrition and excretion.

Hence, the correct answer is option ‘C’ i.e, Nutrition and excretion.

Note: The mammals which have allantois with that of amnion and chorion are called amniotes. For example – humans, reptiles, etc. The vertebrates that lack the allantois are called anamniotes. Example – amphibians, non-tetrapod fish, etc.