EMBRYOLOGY: PRACTICE 1

                                      SINGLE BEST OPTION SERIES
  
                    INSTRUCTION: SELECT THE SINGLE BEST OPTION
   

1.             The period of embryogenesis is the .............................of human development in-utero.
   a.       First four weeks
   b.      First eight weeks
   c.       First twelve weeks
   d.      First twenty-four weeks
   e.      First week
   2.       Concerning oogenesis, the development of primordial follicles at puberty include the following stages except:
   a.       Primary stage
   b.      Antral stage
   c.       Acrosomal reaction stage
   d.      Pre-ovulatory stage
   e.      None of the above
   3.       The study of embryological origin and causes of birth defects is called:
   a.       Organogenesis
   b.      Teratology
   c.       Molecular biology
   d.      Developmental toxicity
   e.      Experimental embryology
   4.       The secondary oocyte during oogenesis is arrested in......................... approximately three hours before ovulation.
   a.       Prophase
   b.      Metaphase
   c.       Interphase
   d.      Anaphase
   e.      Telophase
   5.       There are approximately -----------------genes in the human genome.
   a.       31 000
   b.      64 000
   c.       33 000
   d.      34 000
   e.      35 000
   6.       The correct sequence of events in spermatogenesis is:
   a.       Type ‘A’ spermatogonia → primordial germ cells → type ‘B’ Spermatogonia → primary spermatocytes → spermatids → secondary spermatocytes.
   b.      Secondary spermatocytes → type ‘A’ spermatogonia → primordial germ cells → primary spermatocytes → spermatids → type ‘B’ spermatogonia
   c.       Primordial germ cells → type ‘A’ spermatogonia → type ‘B’ spermatogonia → primary spermatocytes → secondary spermatocytes → spermatids
   d.      Primary spermatocytes → secondary spermatocytes → spermatids → type ‘A’ spermatogonia → type ‘B’ spermatogonia → primordial germ cells.
   e.      None of the above
   7.       Which of the following is incorrect?
   a.       During meiosis, one primary oocyte gives rise to four daughter cells but only one of these develops into a mature gamete.
   b.      During meiosis, one primary spermatocyte gives rise to four daughter cells and all four develop into mature gametes
   c.       Meiosis requires two cell divisions to reduce the number of chromosomes to the haploid number
   d.      Mitosis is the process where one cell divides, giving rise to four daughter cells that are genetically identical to the parent cell.
   e.      Human gametes are embryologically derived from primordial germ cells in the yolk sac.
   8.       Which of the following is incorrect about spermatogenesis?
   a.       Spermatogonia and spermatids remain embedded in deep recesses of Sertoli cells throughout their development
   b.      Type ‘A’ spermatogonia undergo meiotic division to produce type ‘B’ spermatogonia
   c.       Primary spermatocytes are formed from type ‘B’ spermatogonia by mitosis
   d.      Spermatids are formed formed when secondary spermatocytes undergo second meiotic division.
   e.      Spermatids are haploid.
   9.       Which of the following is incorrect?
   a.       The most common chromosomal abnormalities in abortuses are Turner syndrome, triploidy and trisomy 16.
   b.      Normal somatic cells are haploid while normal human gametes are diploid
   c.       In women, the incidence of chromosomal abnormalities in their conceptus including nondisjunction increases with age, especially at 35 years and older.
   d.      In mosaicism, some cells have normal chromosome number while others are normal.
   e.      Down syndrome results more from nondisjunction than translocation.
   10.   The following events occur during spermiogenesis except:
   a.       Acrosome formation
   b.      Formation of the neck, middle and tail piece of spermatozoon
   c.       Shedding of most of the cytoplasm of spermatids
   d.      Condensation of nucleus in spermatids
   e.      None of the above
   
   
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