Question

Which of the following groups of organisms bear young ones with short development periods inside the mother and complete their development in a pouch outside the mother’s body?
A. Marsupials
B. Amniotes
C. Placentals
D. Monotremes
E. Prokaryotes

Answer 1

Hint: Every organism produces progeny in different ways that include binary fusion, laying eggs, giving birth to premature babies, etc. The organism that bears young ones with short development periods inside the mother belongs to the class Metatheria.

Complete solution:
Marsupials are a group of mammals that contain pouches in their body like the wallaby and kangaroo at left. They give birth to premature babies. They do not have a long gestation period like placental mammals. The young animal is helpless, they climb from the mother's birth canal to the nipples. There, it grabs on with its mouth and continues to develop, often for weeks or months depending on the species. Amniotes are a group of vertebrates that undergo fetal development within an amnion and include birds, reptiles and mammals. Amniotes develop in a membrane that covers the embryo completely and the embryo develops fully in it. Placentals are organisms that supply food and nutrients to the fetus through a special blood vessel inside their body. Lastly, reproduction in prokaryotes is asexual like binary fission. The DNA of a prokaryote exists as a single, which is a circular chromosome. They do not undergo mitosis. the chromosome replicates and the two copies separate from one another, due to the growth of the cell.
Hence, the correct answer is option A.

Note: The amnion is a membrane that closely covers the embryo when first formed. It fills with the amniotic fluid which causes the amnion to expand and become the amniotic sac. It serves to provide a protective environment for the developing embryo or fetus. It has three cavities called amnion, chorion and yolk sac