JS
Forum Senior
Topics: 16
Posts: 95
|
1.Ultrasound examination of an anovulatory patient with polycystic ovary syndrome (PCOS) reveals that her ovaries contain multiple enlarged but immature follicles. The oocytes within these follicles have advanced to which of the following stages of meiosis?
A. First meiotic prophase
B. First meiotic metaphase
C. Second meiotic prophase
D. Second meiotic metaphase
E. Pronuclear stage
2. An undescended testis of a prepubertal male is removed since it is at higher risk to develop testicular cancer. Histologic analysis reveals that cells of the germ line in this testis have have advanced as far as which of the following stages of development?
A. Primordial germ cell
B. Spermatogonium
C. Primary spermatocyte
D. Secondary spermatocyte
E. Definitive spermatocyte
3. A female patient with unexplained infertility is treated with menopausal gonadotropin and pure follicle stimulating hormone to induce follicular development. Several oocytes are aspirated from enlarged follicles and cultured in nutrient medium until they reach the normal second stage of meiotic arrest before they are fertilized. Fertilization is therefore carried out at which of the following stages of oocyte development?
A. Prophase of the primary oocyte
B. Metaphase of the primary oocyte
C. Prophase of the Secondary oocyte
D. Metaphase of the Secondary oocyte
E. Prophase of the definitive oocyte
F. Metaphase of the definitive oocyte
4. A 22 year old male with respiratory difficulties is diagnosed with a mediastinal germ cell tumor. The primordial germ cell that gave rise to this tumor inappropriately migrated to this site from which of the following tissues?
A. Liver
B. Testis
C. Yolk sac
D. Allantois
E. Spleen
5. Chromosome analysis is carried out on the polar bodies of a woman for screening prior to in vitro fertilization. Polar bodies removed from some oocytes contain two copies of chromosome 21 while others contain no copies of chromosome 21. The woman displays none of the characteristics of Down syndrome and so the nondisjunction that resulted in this condition must have occurred in which of the following cells?
A. Primary oocyte in her mother's germline
B. Secondary oocyte in her mother's germline germline
C. Blastomere in her mother's germline
D. Primary oocyte in her own germ line
E. Secondary oocyte in her own germline
F. Blastomere in her own germ line
6. A female patient in the late first trimester of pregnancy exhibits hypertension, vaginal bleeding and edema. A conceptus characterized by multiple fluid-filled vesicles and the absence of a fetus is spontaneously aborted a week later. Chromosome analysis reveals a 46, XX karyotype but all of the chromosomes are of paternal origin. Which of the following tissues failed to develop in this conceptus?
A. Cytotrophoblast
B. Outer cell mass
C. Epiblast
D. Primary villi
E. Syncytiotrophoblast
7. A conceptus characterized by patches of cystic villi and an underdeveloped fetus is spontaneously aborted in the second trimester. The karyoype of the fetal tissues is 69, XXX. What is (are) the parental origin(s) of this triploid complement of chromosomes?
A. 69 from the mother
B. 46 from the mother and 23 from the father
C. 69 from the father
D. 46 from the father and 23 from the mother
8. Two children from different families harbor the mutation for Huntington's chorea. In one case, symptoms of the disease appear early in life and are severe while in the other, milder symptoms are exhibited much later in life. How are these differences in onset and severity of the disease best explained?
A. The patients have different life-styles
B. The patients are of different sex
C. The mutations occurred at different sites
D. The mutations arose spontaneously in these patients
E. Different parental origins of the mutations
9. A female patient spontaneously aborts a hydatidiform mole. Follow-up monitoring of which of the following hormones is typically carried out to definitively reveal whether or not any remnants of the mole remain?
A. Estrogen
B. Adrenocortical hormone
C. Human chorionic gonadotropin
D. Follicle stimulating hormone
E. Progesterone
10. Which of the following processes occurs differently in the male and female germ line, thus explaining the phenotype of a complete hydatidiform mole and differences in expression of mutations that underlie diseases such as Huntington's chorea, neurofibromatosis and myotonic dystrophy?
A. Spontaneous mutation
B. Nondisjunction
C. Translocation
D. Genomic imprinting
E. Recombinatio
11.An infant exhibits agenesis of caudal structures and reduction and fusion of the lower extremities. A possible genetic basis of this abnormality is best explained by a mutation of which of the following genes?
A. LIM1
B. Goosecoid
C. Nodal
D. Brachyury
E. Noggin
12. Knockout of Lim-1 in mice results in total absence of the head while remaining structures of the embryo are virtually normal. The expression of Lim-1 is thus normally restricted to which of the following tissues?
A. Paraxial mesoderm
B. Intermediate mesoderm
C. Lateral Plate mesoderm
D. Somitic mesoderm
E. Prechordal mesoderm
13. Which of the following classes of genes is primarily involved in the establishment of axes of symmetry (craniocaudal; dorsoventral; and right-left) of the human embryo?
A. Maternal effect
B. Zygotic
C. Homeobox
D. Segmentation
E. Pair-rule
14. Activation of Mad (mothers against decapentaplegegic) genes by dorsalizing and ventralizing factors play key roles in mesoderm induction in animal embryos. A mad-related gene in humans, DPC4 is disrupted in a large proportion of human pancreatic cancers and some colon cancers implicating DPC4 as which of the following kinds of genes?
A. Maternal effect
B. Tumor suppressor
C. Protooncogene
D. Oncogene
15. Epigenetic development of mammalian embryos (including humans) is regulated by which of the following gene cascades?
A. Zygotic -> Maternal effect -> Hox -> cell adhesion genes
B. Hox -> zygotic -> cell adhesion genes -> maternal effect
C. Cell adhesion genes -> zygotic -> maternal effect -> Hox
D. Maternal effect -> zygotic -> Hox -> cell adhesion genes
E. Hox -> maternal effect -> cell adhesion genes -> zygote
idea Please provide some explanations too !
JS
|
| phuluong2k
Forum Fanatic
Topics: 714
Posts: 2,008
|
1 A
2 A
3 D
4 C
5 E ???
6 C
7 D
8 E different triplet repeat
|
| phuluong2k
Forum Fanatic
Topics: 714
Posts: 2,008
|
8 E, the triplet repeat in different generations
9 C Role of placenta in secretion of hCG
10
11
12. E ??
13. Segmentation ???
14 B
|
| JS
Forum Senior
Topics: 16
Posts: 95
|
Thankyou phuluong2k,
These are the right answers provided..
1. A
2. A
3. D
4. C
5. F
6. C
7. D
8. E
9. C
10. D
11. D
12. E
13. A
14. B
15. D
|
|
| |
| | | | |
