Exam 33: Reproduction and Development

Why does an embryo undergo the process of gastrulation?

During the rapid cell division that occurs after fertilization,cells increase rapidly in number,but the embryo stays the same size.The cells of this very early embryo must

Fertilization of an egg with more than one sperm

The second meiotic division in a secondary oocyte is completed

Both oogenesis and spermatogenesis

Which of the following statements about sexual reproduction in animals is true?

Land animals are more likely to undergo fertilization outside their bodies because gametes require dry environments in order to fuse and develop.

In mammals,the trophoblast layer in a blastocyst will become part of the

Why does the tip of a sperm contain enzymes?

In mammals,the blastocyst consists of the trophoblast and the

Haploid gametes are produced by ________.

Human chorionic gonadotropic produced by the trophoblast signals the ovaries to produce progesterone,which maintains the pregnancy and prevents ovulation.This effect of progesterone is used artificially in

Morning sickness is caused by the hormone ________.

The scarcity of food causes aphids to develop wings.This is an example of positional information affecting gene expression.

Humans complete their development in a protected environment inside their mothers' bodies,in the

Some organisms can produce offspring genetically identical to themselves,without a mate.

By the end of a normal first trimester,the zygote has

In humans,germ line cells originate in the

In oogenesis,polar bodies produced from a primary oocyte ________ the secondary oocyte produced from that same primary oocyte.

Chemicals that disrupt normal gene expression during development are