Test Bank for The Developing Human Clinically Oriented Embryology 8th Edition by Moore LATEST 2021.

Moore: The Developing Human, 8th Edition 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 a. Polar body b. Capacitation c. Acrosome d. Zona pellucida e. Pronuclei 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 a. Polar body b. Capacitation c. Acrosome d. Zona pellucida e. Pronuclei 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 a. Polar body b. Capacitation c. Acrosome d. Zona pellucida e. Pronuclei ANS: C The acrosome is a caplike 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. 4. ________ Polar body a. A b. B c. C d. D e. E ANS: D The first polar body forms during the first meiotic division. Note that it is inside the zona pellucida with the secondary oocyte. Although it may divide into two polar bodies, these cells degenerate. The secondary oocyte receives the same number of chromosomes as the polar body; however, it gets almost all the cytoplasm. 5. ________ Zona pellucida a. A b. B c. C d. D e. E ANS: C The zona pellucida surrounds the secondary oocyte and the polar body. This membrane is surrounded by a layer of follicular cells called the corona radiata. The zona pellucida appears homogeneous in the fresh condition, but under the electron microscope it appears granular and shows some concentric layering.