Question

The placenta formed from the yolk sac is called allantoic. State whether the given statement is true or false.

Answer 1

Hint: The placenta is the organ that is formed during the pregnancy. They remain attached to the wall of the uterus. In the placenta of the mammals, the allantois is part which forms an axis for the development of the umbilical cord.

Complete answer:
The placenta is the modified egg. The allantois and the yolk sac become umbilical cords which provide a connection for the passage of food that reaches the fetus and removes waste. In the case of egg-producing animals, the yolk is the nutrients carrying part of the egg whose main function is to the food supply to the developing embryo. As it stores food, it is rich in various vitamins, minerals, lipids and proteins. The yolk sac also helps in the formation of the blood cell in the embryo until the placenta is developed.
The allantoic is the hollow structure which is filled with clear fluids that form the part of developing conceptus which consists of all embryonic tissues. The allantois helps the fetus to exchange gases and handle liquid waste materials and it is primarily involved in nutrition and excretion and is webbed with blood vessels. The function of the allantois is to collect liquid waste from the embryo. The allantois in the human is a caudal out-pouching of the yolk sac, which is surrounded by the mesodermal connecting stalk known as the body-stalk. The vasculature of the body-stalk develops into umbilical arteries which carry deoxygenated blood to the placenta. The fetus is composed of 4 fetal membranes; they are yolk sac, amnion, chorion and allantois. The allantoic and the yolk sac together becomes the umbilical cord.
Hence, the correct option is false.

Note: The placenta is the temporary organ which connects the developing embryo to the wall of the uterine. It gives oxygen and nutrients to the baby. The embryonic allantois developed into the fetal urachus, which connects the fetal bladder to the yolk sac and it helps in the removal of nitrogenous waste from the fetal bladder.