MCQ ON CYTOGENETICS PART 3
This part contains MCQs based on Meiosis cell division, its various phases and consequences.
1. Which of the following will likely to see in zygotene stage?
(a) Condensed chromosome
(b) Thin chromatid
(c) Bead on a string model
(d) O shaped chromosome
Ans. (a) Condensed chromosome
Explanation: The zygotene chromosomes are more condensed than that in leptotene stage. The ball and seen mainly in leptotene stage while the O shaped structure is in diplotene. The thin chromatins are seen in interphase or pre-leptotene.
2. Which of the following events takes place in zygotene phase?
(d) Equatorial ring formation
Ans. (a) Synapsis
3. If the pairing starts at terminal and proceeds towards centre it is known as?
Ans. (b) Proterminal
4. What percentage of DNA synthesized during zygotene?
Ans. (a) 0.4%
Read….MITOSIS & MEIOSIS- CELL DIVISION
5. What is the size of DNA that is left to be replicated in zygotene?
(a) 100 bp
(d) 104 kb
Ans. (c) 104bp
Read…DNA REPLICATION-DEFINITION & PROCESS
6. Which of the following doesn’t lead to pairing in meiosis?
(a) 0.3% DNA replication that was left after S phase
(b) Retardation factor
(c) Turbulence factor
(d) Precocity factor
Ans. (c) Turbulence factor
7. What is the size of each fiber of the synaptonemal complex responsible for the pairing of homologous chromosomes during meiosis?
(a) 5 nm
(b) 10 nm
(c) 15 nm
(d) 20 nm
Ans. (b) 10 nm
See also… HOMOLOGOUS CHROMOSOMES- KEY FEATURES
8. The synaptonemal complex has ____________ filaments.
Ans. (c) 3
9. The synaptonemal complex is a proteinous complex, which of the protein is not present in it?
(a) Rec 11
(d) Zip 1
Ans. (c) Actin
10. The pairing of the chromosome is mediated by _______________ interactions.
Ans. (d) Electrostatic
Read… SYNAPSIS MEANING- PROCESS & FUNCTION
11. During pairing of the chromosomes which of the following is not true?
(a) There are 3 lateral filaments A, B, C
(b) The A point pairs with adjacent A of other chromatid
(c) The B point pairs with adjacent B of other chromatid
(d) The C point pairs with C
Ans. (b) The A point pairs with adjacent A of other chromatid
12. The fibers of the lateral filament are called____________
(c) Synaptic clefts
Ans. (b) Synaptomere
13. The point where the synaptonemal complex is attached to nuclear envelope is called _______________
(a) Bouque stick
(b) Meiotic point
(c) Fixation point
Ans. (c) Fixation point
14. Which is the longest stage of spermatogenesis?
Ans. (b) Pachytene
Explanation: Pachytene is the longest stage for spermatogenesis which includes crossing over. So, it is a vital stage that leads to an increase in variability.
15. Which of the following is true during pachytene stage?
(a) The crossing over takes place while the chiasma forms later
(b) The chaisma forms earlier while crossing over takes place later
(c) Both simultaneously
(d) None of these
Ans. (a) The crossing over takes place while the chiasma forms later
16. What is the fate of nucleolus in pachytene?
(a) Nucleolus disappears
(b) Nucleolus appears like thin chromatin
(c) Nucleolus is disintegrated
(d) Nucleolus remains attached to particular tetrad
Ans. (d) Nucleolus remains attached to particular tetrad
17. The polar arrangement of the chromosome is a characteristic of the leptotene and zygotene stage. It is generally seen to disappear in the stage:
Ans. (c) Pachytene
18. Crossing over doesn’t take place ________________
(a) Between two sister chromatids
(b) Between two non-sister chromatids
(c) For recombination repair
(d) Between three chromatids
Ans. (d) Between three chromatids
See… CROSSING OVER- PROCESS & FUNCTION
19. What is the stretch of DNA remaining unreplicated during pachytene?
(d) 10 kb
Ans. (a) 200bp
20. Electron dense bars located in the synaptonemal complex in pachytene is?
(a) LC complex
(b) Recombination nodule
(c) Pachytene cluster
Ans. (b) Recombination nodule
Explanation: The recombination nodule is a multienzyme complex that is responsible for recombination of two chromatids.
21. The separation of the chromosomes in diplotene stage starts at ____________
(b) Region before telomere
(c) Region beside centromere
Ans. (d) Centromere
Explanation: The separation of the chromosomes in diplotene stage starts at the centromere and then proceeds towards the telomere. This process is called terminalization.
22. The number of chiasmata is variable and maximum number of chiasma may be 13-14. What is the normal number of chiasma seen in diplotene chromosomes?
Ans. (b) 4
23. The ratio of Number of chiasma / total number of bivalent shows?
(a) Degree of terminalization
(b) Frequency of terminaliztaion
(c) Degree of crossing over
(d) Frequency of crossing over
Ans. (d) Frequency of crossing over
24. According to Darlington, which of the following force leads to terminalization?
Ans. (a) Electrostatic
25. Choose the wrong one about diplotene?
(a) Endoplasmic vesicles increase in the number
(b) Nucleolus condenses
(c) Chromatid body is seen
(d) Chromosomes rotate by 180 degree to terminalize
Ans. (b) Nucleolus condenses
26. What is the bivalent shape in diakinesis?
(a) X shaped
(b) O shaped
(c) Y shaped
(d) Star shaped
Ans. (b) O shaped
27. The number of chiasma in diakinesis stage _________
(c) Remains same
(d) There are no chiasma left
Ans. (b) Decreases
28. In which phase finally Nuclear envelope breaks down and spindle fiber attaches to chromosomes?
(b) Pro metaphase
Ans. (b) Pro metaphase
29. The movement of the chromosome in metaphase is known as:
Ans. (d) Congression
30. How many cells are produced by meiosis 2?
Ans. (b) 2
Explanation: The number of cells formed at the end of the entire process of meiosis is 4, but only meiosis 2 produces 2 cells.
31. The anaphase 1 shows which of the following?
(a) Chromatids separate to one pole
(b) Centromere is 1st to separate
(c) The chromosomes separate to 4 cells
(d) Each homologue reaches opposite pole
Ans. (d) Each homologue reaches opposite pole
32. If your cell has 24 chromatids, what will be the number of a chromosome at each pole after anaphase 1?
Ans. (a) 6
Explanation: 24 chromatids mean 12 chromosmes. Since, Anaphase 1 is reduction division so each homologue should move to opposite pole, resulting in reduction. Therefore, finally there will be only 6 chromosomes at each pole.
33. The chromosomes at the end of anaphase are:
(a) very condensed
(c) Both a & b
(d) None of these
Ans. (c) Both a & b
34. Which of the following can be true with telophase 1?
(a) The chromosomes de-condensed
(b) The sister chromatids of the bivalent is visible
(c) The nuclear membrane breaks down
(d) It is of very long duration
Ans. (b) The sister chromatids of the bivalent is visible
35. Which of the following is wrong statement about Telophase1?
(a) In most animals it is absent
(b) The chromosomes can’t relax and are compacted
(c) The cell passes into diffuse interphase
(d) The nuclear membrane reforms
Ans. (b) The chromosomes can’t relax and are compacted
36. The prophase 2 is ______________ mitotic prophase.
(a) Same as
(b) Similar to
(c) Different from
Ans. (b) Similar to
37. Which of the following is not true for meiosis 2?
(a) Doubled chromosomes line along equatorial plate
(b) Karyokinesis is followed by cytokinesis
(c) The chromosome number is reduced
(d) The anaphase chromosomes start to spate from the centre
Ans. (c) The chromosome number is reduced
Explanation: In meiosis 2 the chromosome number remains the same as this is not a reduction division. The meiosis 1 is the reduction division.
38. The term meiosis, derived from the Greek word for “lessening” was coined in 1905 by:
(a) T.H Morgan
(c) Farmer and Moore
(d) Gregor Mendel
Ans. (c) Farmer and Moore
39. Meiosis was first observed in sea urchin eggs in 1876 by a German biologist:
(a) Oscar Hertwig
(c) Farmer and Moore
(d) Gregor Mendel
Ans. (a) Oscar Hertwig
40. Which of the following is the defining feature of mammalian meiosis, ensures that haploid gametes differ genetically from their adult precursors and is the real engine of genetic diversity and evolution?
(a) Chromosomal aberration
(b) Chromosomal recombination
(c) Chromosome duplication
(d) Chromosomal pairing
Ans. Chromosomal recombination
41. The essential difference between mitotic and meiotic replication is that a single DNA duplication step is followed by only one cell division in mitosis but two cell divisions in meiosis which results?
(a) Two daughter cells
(b) One daughter cells
(c) Eight daughter cells
(d) four daughter cells
Ans. (d) four daughter cells
42. Meiosis consists of one round of DNA replication and two rounds of————–
(a) chromosome segregation
(b) DNA duplication
(c) chromosome pairing
(d) None of these
Ans. (a) chromosome segregation
MCQ ON CYTOGENETICS PART1
MCQ ON CYTOGENETICS PART 2