NEET BIOLOGY

Detailed explanation-1: -placental mammal, (infraclass Eutheria), any member of the mammalian group characterized by the presence of a placenta, a vascular organ that develops during gestation, which facilitates exchange of nutrients and wastes between the blood of the mother and that of the fetus.

Detailed explanation-2: -Eutherians all have a chorioallantoic placenta, a remarkable organ that forms after conception at the site where the embryo makes contact with the lining of the mother’s uterus (Langer, 2008).

Detailed explanation-3: -Placental mammals are a rather diverse group, with nearly 4000 described species, mostly rodents and bats (photos at left). The placental mammals include such diverse forms as whales, elephants, shrews, and armadillos.

Detailed explanation-4: -Eutherians, like their closest relatives the marsupials, give birth to live young. In eutherians, however, the young are nurtured within the body of the mother by the placenta, which allows nutrients to pass from the blood of the mother almost directly into the blood of the young.

Detailed explanation-5: -Eutheria are a group of mammals consisting of placental mammals. The placental mammals include such diverse forms as whales, elephants, shrews, and humans. They all bear live young, which are nourished before birth in the mother’s uterus through a specialized embryonic organ attached to the uterus wall, the placenta.