Which of the following statements is INCORRECT? Mitosis is a conservative mechanism that preserves the genetic status quo. Meiosis is a special type of cellular division that occurs in gametes. After mitosis, two identical 2n daughter cells are produced. After meiosis I, four n daughter cells are produced.
Oogenesis
The formation of the ovum (mature female gamete) from undifferentiated germ cells is called oogenesis. This process takes place in the ovaries (female gonads). Oogenesis consists of three stages known as the multiplication phase, growth phase, and maturation phase.
Cell Division
Cell division involves the formation of new daughter cells from the parent cells. It is a part of the cell cycle that takes place in both prokaryotic and eukaryotic organisms. Cell division is required for three main reasons:
- Which of the following statements is INCORRECT?
- Mitosis is a conservative mechanism that preserves the genetic status quo.
- Meiosis is a special type of cellular division that occurs in gametes.
- After mitosis, two identical 2n daughter cells are produced.
- After meiosis I, four n daughter cells are produced.
- Genetic recombination or diversity is a feature of __________.
|
A. |
Meiosis I |
C. |
Mitosis |
|
B. |
Meiosis II |
D. |
Choices A, B, and C are correct. |
- The following are cellular events during prophase I, EXCEPT:
|
A. |
Chromatin condensation |
C. |
Crossing-over |
|
B. |
Synapsis |
D. |
Paired homologs attach to spindle fibers. |
- Which of the following statements refers to synapsis?
- It is the pairing of homologous chromosomes during meiosis.
- It is the alignment of chromosomes on the equatorial plate.
- It is the exchange of parts between non-sister chromatids.
- It represents the sites where crossing-over occurred.
- Which of the following events below is associated with zygotene?
|
A. |
Synapsis |
C. |
Appearance of recombination nodules |
|
B. |
Crossing-over |
D. |
Crossover points appear as chiasmata. |
- Chiasmata are observed during the following stages of meiosis I, EXCEPT:
|
A. |
Diplotene |
C. |
Metaphase I |
|
B. |
Diakinesis |
D. |
Anaphase I |
- Which of the following statements is INCORRECT?
- Unlike in meiosis I, homologous chromosomes do not pair up during mitosis and meiosis II.
- Genetic exchange between homologous chromosomes does not occur during mitosis.
- Homologous chromosomes, not sister chromatids, attach to spindle fibers from opposite poles during metaphase I.
- During meiosis, the centromeres of the sister chromatids separate at the beginning of anaphase I.
- Which of the following statements is TRUE of interkinesis?
- It is a relatively brief interphase between telophase I and prophase II.
- Chromosomes duplicate during interkinesis.
- DNA undergoes semiconservative replication during this interphase.
- In all species, chromosomes usually decondense during this time.
- Bivalents or tetrads are first observed in which stage of meiosis?
|
A. |
Leptotene |
C. |
Pachytene |
|
B. |
Zygotene |
D. |
Diplotene |
- The type of cell division that converts spermatogonia and oogonia to primary spermatocytes and primary oocytes respectively is __________.
|
A. |
Meiosis I |
C. |
Mitosis |
|
B. |
Meiosis II |
D. |
Binary fission |
- The following are haploid cells, EXCEPT:
|
A. |
Spermatids and spermatozoa |
C. |
Ovum and second polar body |
|
B. |
Primary oocytes and primary spermatocytes |
D. |
Secondary oocytes and first polar body |
- Which of the following statements is INCORRECT?
- By six months after conception, fetal ovaries contain about half a million primary oocytes arrested in the diplotene stage.
- At ovulation, a released primary oocyte completes meiosis I and proceeds as far as metaphase II.
- Fertilization quickly completes meiosis II.
- Only two of the three products of a single meiosis serve as the female gametes.
- A normal spermatozoon carries __________.
|
A. |
Both X and Y chromosomes |
C. |
Either an X or a Y chromosome |
|
B. |
An X chromosome only |
D. |
A Y chromosome only |
- Spermatogenesis takes place in which of the following structures?
|
A. |
Ovarian follicles |
C. |
Male urethra |
|
B. |
Glans penis |
D. |
Seminiferous tubules of the testes |
- During spermatogenesis, __________ undergo meiosis II and give rise to spermatids.
|
A. |
Primary spermatocytes |
C. |
Spermatogonia |
|
B. |
Secondary spermatocytes |
D. |
First polar body |
- A normal ovum carries __________.
|
A. |
Both X and Y chromosomes |
C. |
Either an X or a Y chromosome |
|
B. |
An X chromosome only |
D. |
A Y chromosome only |
- Which of the following is NOT a characteristic of X-linked recessive traits?
- The trait appears more in females than males.
- The mutation will never be passed from father to son.
- An affected male passes the X-linked mutation to all his daughters.
- With a rare affected female, all her sons will be affected and all her daughters will be carriers.
- Which of the following statements is NOT TRUE of X-linked dominant traits?
- The trait is seen in every generation as long as affected the males have female children.
- All the daughters but none of the sons of an affected male will be affected.
- Sons and daughters of affected females each have a 50% chance of being affected.
- Hemophilia, red-green color blindness, and vitamin D-resistant rickets are X-linked dominant traits.
- Which of the following statements is NOT TRUE of Y-linked traits?
- Maleness and male fertility are the only known Y-linked traits in humans.
- The trait is only seen in males.
- Not all male descendants of an affected man will exhibit the trait.
- Females cannot transmit the trait.
- Which of the following statements is INCORRECT?
- Sex-limited traits affect a structure or process that is found in one sex but not in the other.
- Sex-influenced traits appear in both sexes.
- Expression of sex-influenced traits may differ between sexes because of hormonal differences.
- Pattern baldness is autosomal recessive in men, but autosomal dominant in women.
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