Question

Unlike eutherians, both monotremes and marsupials

A) lack nipples.
B) have some embryonic development outside the mother's uterus.
C) lay eggs.
D) are found in Australia and Africa.
E) include only insectivores and herbivores.

Answer 1

Monotremes lay eggs and the young are nourished by milk secreted by the mother. Marsupials give birth to underdeveloped embryos that complete their development in a pouch. Eutherian mammals give birth to fully developed live young.

Step-by-step explanation:

Monotremes, including the platypus and echidnas, lay eggs instead of giving birth to live young. The eggs have a leathery shell and are retained within the mother's reproductive tract until they are ready to hatch. Once hatched, the female monotreme secretes milk to nourish the young. Monotremes are unique among mammals in their reproductive strategy.

In contrast, marsupials, like kangaroos and koalas, give birth to underdeveloped embryos that complete their development in a pouch on the mother's body. Eutherian mammals, or placental mammals, give birth to fully developed live young after an extended period of gestation in the mother's uterus.