Sunday, 8 March 2015

ANATOMY MCQ( Multiple choice questions) WITH EXPLANATION 2015

MCQ QUESTIONS WITH EXPLANATION  IN ANATOMY 2015 important topics for DNB-CET, AIPGMEE, FMGE, DNB-PDCET, UPSC-CMS online medical examination .

1. The part of the sperm containing proteolytic enzymes to digest the zona pellucida is the:

A. capacitor
B. head
C. corona
D. acrosome
E. cumulus

D. is correct.
The acrosome is the part of the sperm containing proteolytic enzymes to digest the zona pellucida. It is exposed by the process of capacitation. Then, under the influence of substances released by corona radiata cells, it releases its proteolytic enzymes and penetrates the oocyte.

2. The ovulated mammalian oocyte is arrested at:

A. prophase of meiosis I
B. metaphase of meiosis I
C. prophase of meiosis II
D. metaphase of meiosis II
E. none of the above

D. is correct.
The long arrest in meiosis occurs in the primary oocyte. These descendants of oogonia begin meiosis before birth and stop dividing during prophase of the first division. Years later, this first division is completed just prior to ovulation. Ovulated secondary oocytes then stop at metaphase II until fertilized.

3. The seven-day blastocyst:

A. has a single layer of trophoblast at the embryonic pole
B. has an amniotic cavity
C. is attached to the endometrial epithelium
D. is surrounded by a degenerating zona pellucida
E. is called the hypoblast

C. is correct.
The decidual reaction of the endometrium creates a nourishing environment for the conceptus a it buries itself by invasion of the uterine endometrial wall. Progesterone produced by the corpus luteum stimulates glandular secretion in the endometrium during the secretory phase of menstruation or early pregnancy.

4. Haploid nuclei that fuse at fertilization are called:

A. homunculi
B. mitotic figures
C. centrioles
D. nucleoli
E. pronuclei

E. is correct.
After the sperm reaches the ovum, it deposits its genetic load, the male pronucleus, into the cytoplasm of the egg. After finally completing the meiotic division that had begun years before, the female pronucleus fuses with the male pronucleus to create the diploid nucleus of the zygote

5. The first week of human development is characterized by formation of the:

A. inner cell mass
B. hypoblast
C. trophoblast
D. blastocyst
E. all of the above

E. is correct.
At four days, the blastocyst cavity of blastocele forms within the morula. Trophoblast are outer cells of the blastocyst, while a knot of cells appears, protruding into the blastocele. This is the inner cell mass. Trophoblast becomes 2 layers: syncytiotrophoblast and cytotrophoblast. Inner cell mass becomes epiblast and hypoblast.

6. During implantation, the blastocyst:

A. implants in the endometrium
B. usually attaches to endometrial epithelium at its embryonic pole
C. usually implants in the posterior wall of the body of the uterus
D. causes change in the endometrial tissues
E. all of the above are correct

E. is correct.
Implantation occurs when the trophoblast cells at the embryonic pole secrete proteolytic enzymes that allow the blastocyst to penetrate the wall of the uterus, usually the posterior wall. The endometrial lining responds to implantation through the decidua reaction, by which it becomes more succulent for nourishing the blastocyst.

7. Capacitation of the sperm:

A. is caused by the zona pellucida
B. occurs in the male
C. prevents polyspermy
D. is essential for fertilization
E. removes the head of the sperm

D. is correct.
Capacitation involves removing the glycoprotein coat and seminal plasma proteins from the head of the sperm, exposing the acrosome and allowing the acrosome reaction to occur. Capacitation occurs within the female genital tract, and without its occurrence, fertilization could not occur.

8. The early stages of cleavage are characterized by:

A. formation of a hollow ball of cells
B. formation of the zona pellucida
C. increase in the size of the cells in the zygote
D. increase in the number of cells in the zygote
E. none of the above

D. is correct.
The earliest stages of cleavage are marked by a series of mitotic divisions that increase the number of cells in the zygote without an increase in size. As the cleavage continues the zygote becomes a morula or a solid ball of 12-16 cels. A cavity forming within the morula transforms it into a blasocyst, at about day 4.

9. The most common site for implantation in ectopic pregnancy is:

A. internal os of the uterus
B. mesentery
C. ovary
D. uterine tube
E. other

D. is correct.
The most common site of ectopic implantation is the uterine tube. The growth of the embryo in this site usually causes rupture of the tube and severe hemorrhage in the mother. Abdominally, an ectopic pregnancy often occurs in the rectouterine pouch, an area between the uterus and the rectum.

10. With the light microscope, the zona pellucida appears as a translucent membrane surrounding the:

A. primary oocyte
B. zygote
C. morula
D. very early blastocyst
E. all of the above are correct

E. is correct.
The zona pellucida persists until early it the blastocyst stage. It dissolves during the blastocyst stage in order that implantation may occur.

11. The amniotic cavity develops:

A. on the tenth day
B. within the outer cell mass
C. within the inner cell mass near the cytotrophoblast
D. in extraembryonic mesoderm
E. none of the above

C. is correct.
The amniotic cavity begins to develop around the 8th ay as a slit-like area within the epiblast near the cytotrophoblast. It usually ha a thin strip of epiblast cells, called amnioblasts, between it and the cytotrophoblast.