Answer the following: More recently evolved organisms have modified the stages of embryological development. Would you expect early or late stages to be modified the most? Why? The basic stages of embryological development are remarkably similar for a wide range of organisms. How would you explain such consistency?

Mammals have unique reproductive adaptations that have contributed to their evolutionary success. One of the distinguishing characteristics of mammals is their mammary glands, which allow for the production of milk. Even the more primitive mammals, such as the duck-billed platypus and the kangaroo, have some type of mammary glands. However, only the placental mammals (e.g. humans, horses, dogs) have a placenta, which supports the internal development of the embryo. The most primitive mammals have no placenta and can’t support the internal development of the embryo. Describe one advantage for an offspring to develop internally as opposed to developing externally (this means inside vs. outside the female’s womb/body)

A. In 1952, the nucleus of a _______________________ embryo was placed into a donor cell.  Was the embryo cloned successfully? ___________________ B. Can the nucleus of an adult cell be injected into an egg cell and produce a clone?