Test Bank For Developing Human Clinically Embryology 9th Edition Moore Persaud

ISBN-10: 1437720021, ISBN-13: 9781437720020 978-1437720020

Chapter 01: Gametogenesis and Fertilization

MULTIPLE CHOICE

Directions: Each group of questions below consists of a numbered list of descriptive words or phrases accompanied by a diagram with certain parts indicated by letters or by a list of lettered headings. For each numbered word or phrase, select the lettered part or heading that matches it correctly and then insert the letter in the space to the right of the appropriate number. Sometimes more than one numbered word or phrase may be correctly matched to the same lettered part or heading.

1. ________ Haploid nuclei that fuse to form a zygote

ANS:   E

The male and female pronuclei are the haploid nuclei of the sperm and oocyte, respectively. They fuse during fertilization to form the diploid nucleus of a zygote. The nucleus occupies most of the head of the sperm, and after it enters the oocyte, it swells to form the male pronucleus. The pronuclei are about equal in size and show similar features.

2. ________ Changes occur in it that inhibit entry of sperm

ANS:   D

The zona pellucida undergoes changes, called the zona reaction, when a sperm contacts the cell membrane of a secondary oocyte. These changes, caused by the release of substances from the oocyte, prevent other sperms from passing through the zona pellucida and entering the oocyte.

3. ________ Contains enzymes that digest a path for the sperm

ANS:   C

The acrosome is a cap-like structure that invests the anterior half of the head of the sperm. It contains enzymes that pass through perforations in its wall and digest a path for the sperm to follow through the zona pellucida to fertilize the oocyte.