Chapter 01: Gametogenesis and Fertilization
Test Bank
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.
, 6.
________ Meiotic spindle
a. A
b. B
c. C
d. D
e. E
ANS: E
Contact of a sperm with the cell membrane of the oocyte stimulates the secondary oocyte to
complete its second meiotic division. This contact also brings about the zona reaction,
preventing entry of more sperms. The sperm penetrates the cell membrane of the
secondary oocyte and then passes into the cytoplasm of the oocyte, leaving its cell
membrane outside the oocyte.
7.
________ Corona radiata
a. A
b. B
c. C
d. D
e. E