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Founder Principle OR Founder Effect

When a few individuals or a small group migrate from a main population, only a limited portion of the parental gene pool is carried away.

In the small migrant group, some genes may be absent or occur in such low frequency that they may be easily lost. 

The unique frequency of genes that arise in population derived from small bands of colonizers or “founders”, has been called the founder effect or founder principle. 

This principle was proposed in 1956 by Harvard evolutionist, Ernst Mayr. 

The founder principle essentially emphasizes the conditions or circumstances that support the operation of Sewall Wright’s genetic drift. 

Example

North American Indian tribes, for the most part, lack the gene IB that governs type B blood. However, in Asia, the ancestral home of the American Indians, the IB gene is widespread. 

The ancestral population of Mongoloids that migrated across the Bering Strait to North America might have been very small.

 Accordingly, the possibility exists that none of the prehistoric immigrants happened to be blood group B. It is also likely that a few individuals of the migrant band did carry the IB gene but they failed to leave descendants.

Evolutionary geneticists interpret this peculiar feature in terms of genetic drift. 

Most of the North American Indians possess only blood group O, or stated another way, contain only the blood allele i.

With few exceptions, the North American Indian tribes have lost not only blood group allele IB but also the allele that controls type A blood (IA). 

The loss of both alleles, IA and IB, by sheer chance perhaps defies credibility. 

Indeed, many modern students of evolution are convinced that some strong selective force led to the rapid elimination of the IAand IB genes in the American Indian populations.

 If this is true, it would provide an impressive example of the action of natural selection in modifying the frequencies of the genes in a population.

Reference

CELL BIOLOGY,GENETICS,MOLECULAR BIOLOGY, EVOLUTION AND ECOLOGY.

VERMA  AND AGARAL

IMPORTANT MCQ ON CELL DIVISION

 MCQ CELL DIVISION

1. An event not occurs in Anaphase-I but occurs in Anaphase-II is

1) Condensation of chromosomes 2) Poleward movement of chromosome

3) Contraction of spindle fibres 4) Splitting of centromere

2. During G₂ – phase of cell cycle  a diploid cell contains the amount of DNA equal to a

1) Diploid cell 2) Tetraploid cell 3) Haploid cell 4) Nothing can be said

3. In which of the following phase crossing over occurs

1) Zygotene 2) Pachytene 3) Diplotene 4) Diakinesis

4. During the cytokinesis of which group forms a contractile mid body

1) Animals 2) Higher plants 3) Fungi 4) Algae

5. In which direction cytokinesis occurs in plants 

1) Centripetal 2) Centrifugal 3) Oblique 4) Equatorial

6. Which of the following  events restore the normal number of chromosomes in life cycle?

1) Mitosis and Meiosis 2) Meiosis and fertilisation

3) Fertilisation and mitosis 4) Only meiosis

7. Match the column A with column B and select the correct answer

Column A		Column B
A	Pachytene	i.	Bouquet stage
B	Zygotene	ii.	Chiasma visible
C	Diplotene	iii.	Terminalisation
D	Leptotene	iv	Gene exchange
E	Diakinesis	v	Synapsis

1) A-i, B-ii, C-iii, D-iv, E-v 2) A-iv, B-v, C-ii, D-i, E-iii

3) A-iii, B-iv, C-v, D-ii, E-i 4) A-ii, B-iii, C-iv, D-i, E-v

8. Which of the plant part  is commonly used for the study of meiosis

1) Root apex 2) Ovary 3) Anther 4) Shoot apex

9. Chromosomal movement in Anaphase is assisted by

1) Astral rays 2) Centrioles 3) NOR 4) Spindle fibres

10. In which of the following phase the nuclear envelope reappears

1) Metaphase 2) Prophase 3) Anaphase 4) Telophase

11. Movement of of chiasmata towards the ends of bivalent is called

1) Terminalisation 2) Diakinesis 3) Interkinesis 4) Heteropycnosis

12. During  meiosis, how many cycles of chromosome division occurs?

1) One 2) Four 3) Two 4) Three

13. Which of the following events does not occurs in prophase?

1) Decondensation of chromatin

2) Condensationof chromatin

3) Appearance of chromosome

4) Disappearance of nuclear membrane and nucleolus

14. In which of the following stage of cell division, number of chromosomes best counted

1) Prophase 2) Metaphase 3) Telophase 4) Interphase

15. How many chromosome shall be present in a diploid cell at mitotic anaphase if its egg cell has 4 chromosome

1) 4 (four) 2) 8 (eight) 3) 12 (twelve) 4) 16 (Sixteen)

16. High level of chromosome coiling exhibits during

1) Prophase 2) Metaphase 3) Telophase 4) Interphase

17. In which sub stage of prophase-I the “Bouquet-stage” occur ?

1) Leptotene 2) Zygotene 3) Pachytene 4) Diplotene

18. During anaphase – II of meiosis each chromosome  contains

1) 4 DNA 2) 3-DNA 3) 2-DNA 4) 1-DNA

19.  The chromosomes are composed of two chromatids  in ?

1) Prophase & metaphase 2) Anaphase and telophase

3) Prophase and telophase 4) Metaphase and anaphase

20.  Each chromosome composed of ……………………..in Anaphase – I

1) One chromatid 2) Two chromatid 3) Four chromatid   4) Many chromatid

21. Gap phase between division phase and start of DNA-replication is called

1) G₁ – phase 2) G₂ – phase 3) M – Phase 4) Interkinesis

22. In meiosis, Division of centromere occurs during

1) Interphase 2) Anaphase – I 3) Anaphase – II 4) Metaphase – I

23. In meiosis, nuclear membrane and nucleolus disappear during

1) Zygotene 2) Pachytene 3) Diakinesis 4) Metaphase – I

24. In cell cycle, which stage is misnomerly called resting phase

1) S-phase 2) Telophase 3) Cytokinesis 4) Interphase

25. Separation of homologous chromosomes during anaphase – I is called

1) Synapsis 2) Disjunction 3) Nondisjunction 4) Crossing over

26. During cell division, spindle fibres attach to which part of chromosome

1) Primary constriction 2) Sec. Constriction

3) Chromomere 4) Chromatid

27. Diakinesis represents

1) transition to prophase 2) transition of metaphase

3) transition to anaphase 4) transition to telophase

28. Synaptonemal complex is characteristic of

1) Mitotic chromosomes 2) Leptotene chromosomes

3) paired meiotic chromosomes 4) Metaphase

29. During which stage a diploid cell becomes tetraploid in mitosis

1) G₂ 2) Prophase 3) Metaphase 4) Anaphase

30. Division of centromere occurs in

1) Prophase 2) Metaphase 3) Anaphase 4) Telophase

31. Each chromosome composed of one chromatid in

1) Anaphase – I 2)Anaphase – II 3) Metaphase – I 4) Metaphase – II

32. If the number of bivalents are 8 in metaphase – I, what shall be the number of chromosomes in daughter cells after meiosis – I and meiosis – II respectively

1) 8 and 4 2) 4 and 4 3) 8 and 8 4) 16 and 8

33. Which one of the following statements is correct?

1) Cell divided by cytokinesis only mitosis

2) DNA is replicated before the start of meiosis only

3) Spindles consisting of microtubules are formed only in mitosis

4) Exchange of genetic materials occurs only in meiosis

34. Which of the following not occurs in Anaphase – I

1) Segregation of homologous chromosomes 2) Shortening in spindle

3) Poleward movement of chromosomes 4) Division of centromere

35. In meiosis

1) Division of nucleus twice but replication of DNA only once

2) Division of nucleus twice and replication of DNA twice

3) Division of nucleus once and replication of DNAis also once

4) Division of nucleus once and DNA replication is twice

36. After meiosis – I, the two chromatids of a chromosome are

1) Genetically similar

2) Genetically different

3) There occurs only one chromatid in each chromosome  

4) None of the above

37. Chiasmata appears during

1) Diakinesis 2) Synaptotene 3) Diplotene 4) Leptotene

38. What happens in synthesis phase during cell cycle

1) DNA synthesis 2) Chromosome number becomes double

3) Formation of two nuclei 4) Synthesis of tubulin proteins

39. Reappearance of nuclear membrane & nucleolus along with thining and elongation in chromosomes are diagnostic characters for the phase

1) Anaphase 2) Metaphase

3) Formation of two nuclei 4) Synthesis of tubulin proteins

39. Reappearance of nuclear membrane and nucleolus along with thining & elongation in chromosomes are diagnostic characters for the phase

1) Anaphase 2) Metaphase 3) Interphase 4) Telophase

40. Condensation of chromosomes and appearance of astral rays occurs during

1) Prophase 2) Metaphase 3) Anaphase 4) Telophase

41. During telophase

1) Nuclear membrane is formed 2) Nucleolus appears

3) Astral rays disappear 4) All the above

42. Chromosomal morphology (Structure) is best observed at

1) Prophase 2) Metaphase 3) Interphase 4) Anaphase

43. Pairing of homologous chromosomes in called

1) Disjunction 2) Synapsis 3) Segregation 4) Polyteny

44. Preparation phase of mitosis is

1) G₁-Phase 2) S-phase 3) Prophase 4) Interphase

45. Synaptonemal complex first appear

1) Leptotene 2) Pachytene 3) Zygotene 4) Diplotene

46. The correct sequence of prophase-I of meiosis is

1) Leptotene, pachytene, zygotene, diplotene, diakinesis

2) Leptotene, diplotene, pachytene, zygotene, diakinesis

3) Leptotene,zygotene, pachytene, diplotene, diakinesis

4) Leptotene, zygotene, diakinesis, diplotene

47. M-phase of cell cycle consist of

1) G₁, S and G₂ phase

2) Prophase, Metaphase, Anaphase, Telophase

3) Interphase, Prophase, Metaphase, Anaphase, Telophase

4) Only prophase

48. If the cell is diploid in G₁ than after the 5 phase cell remain/become

1) n 2) 4n 3) 8n 4) 2n

49. Nuclear membrane disappears in

1) Late prophase 2) Early prophase 3) Metaphase 4) Telophase

50. Pre-DNA synthesis phase is

1) G₁ – phase 2) G₂ – phase 3) S – phase 4) Prophase

51. Synapsis occurs between

1) Two homologus chromosomes 2) A male and a female gamete

3) mRNA and ribosomes 4) Spindle fibres and centromere

52. Synapsis occurs during:

1) Leptotene 2) Zygotene  3) Pachytene 4) Diplotene

53. During mitosis ER and nucleolus begin to disappear at:

1) Early prophase 2) Late prophase 3) Early metaphase 4) Lat e metaphase

54. Which stages of cell division do segregation of chromosome and condensation of chromatin respectively occurs?

    1) Prophase – Anaphase 2) Metaphase – Telophase

    3) Telophase – Metaphase 4) Late Anaphase – Prophase

55. Select the correct option with respect to mitosis

    1) Chromatids separate but remain in the centre of the cell in anaphase

    2) Chromatids start moving towards opposite poles in telophase

    3) Golgi complex and endoplasmic reticulum are still visible at the end of prophase

    4) Chromosomes move to the spindle equator and get aligned along equatorial plate in metaphase    

56. At metaphase, chromosomes are attached to the spindle fibres by their  

    1) Centromere 2) Satellites

    3) Secondary constrictions 4) Kinetochores

57. Meiosis is not having the one of the character out of the four given below

1) It involves two stages of DNA replication, one before meiosis-I and another before meiosis-II

2) It involves recombination and crossing over

3) Sister chromatids separate during anapahase-II

5) Nuclear membrane disappears during prophase

58. During gamete formation, the enzyme recombinase participates during

1) Prophase – I 2) Prophase – II 3) Metaphase – I 4) Anaphase II

59. Identify the stage in which crossing over occurs

1) Prophase of Mitosis 2) Both prophase and metaphase of mitosis  

3) Prophase I during meiosis 4) Prophase II during meiosis

60. Identify the meiotic stage in which the homologous chromosomes separate while the sister chromatids remain associated at their centromeres

1) Anaphase I 2) Anaphase II 3) Metaphase I 4) Metaphase

61. Which of the following is wrong about G₁ phase?

1) G-1 stage followed by Mitosis 2) Cell is metabolically active

3) Cell grows continuously 4) Cell does not replicate its DNA

62. Select the answer which gives correct identification of the stage with its characteristics.

 

1)	Telophase	Endoplasmic reticulum and nucleolus not reformed yet .
2)	Telophase	Nuclear envelop reforms golgi complex reforms
3)	Late anaphase	Chromosomes move a away from equatorial plate, golgi complex not present
4)	Cytokinasis	Cell plate formed, mitochondria distributed between two daughter cells

63. The complex formed by a pair of synapsed homologous chromosomes is called

1) Axoneme 2) Equatorial plate 3) Kinetochore 4) Bivalent

64. In which phase of cell cycle the amount of DNA in a diploid cell become four times as compared to a haploid cell?
1) G₁ 2) S 3) G₂, S & M 4) G_°

65. During which phase(s) of cell cycle, amount of DNA in a cell remains at 4C level if the initial amount is denoted as 2C?

1) G₀ and G₁ 2) G₁ and S 3) Only G₂ 4) G₂ and M

66. In ‘S’ phase of the cell cycle?

1) Amount of DNA doubles in each cell 2) Amount of DNA remains same in each cell

3) Chromosome number is increased 4) Amount of DNA is reduced to half in each cell

67. The enzyme recombinase is required at which stage of meiosis:

1)  Pachytene 2) Zygotene 3) Diplotene 4) Diakinesis

68.  Which of the following is longest phase of the cell cycle?

1) Prophase 2) Interphase 3) Telophase 4) M – phase

69. A somatic cell that has just completed the S phase os its cell cycle, as compared to gamete of the same species, has:

1) same number of chromosomes but twice the amount of DNA

2) twice the number of chromosomes and four times the amount of DNA

3) four times number of chromosomes and twice  the amount of DNA

4) twice the number of chromosomes and twice the amount of DNA

70. Arrange the following events of meiosis in correct sequence:

a) crossing over b) Synapsis

c) Terminalisation of chaismata 4) Disappearance of nucleolus

1) b, c, d, a 2) b, a, d, c 3) b, a, c, d 4) a, b, c, d

71. Which one is correct for G₀ stage?

I. is a quiescent stage

II. In this phase cell cycle is stopped

III. G₀ cells do not grow or proliferate but metabolically active

IV. G₀ cells can divide in response to some stimulus

1) All are correct 2) I, II, III are correct

3) I, II are correct 4) Only I and IV are correct

72. Which of the following is not correctly matches a phase of the cell cycle with its function?

1) Second gap phase – Period of cytoplasmic growth

2) First gap phase – Most of the organelle duplication

3) Interphase – Phase of preparation for cell division

4) DNA synthesis phase – Doubling of number of chromosome in cell

73. Mark incorrect statements

A) meiosis involves only a single cycle of DNA replication

B) Four haploid cells are formed at the end of meiosis – I

C) Meiosis occurs in diploid cells

D) In yeast, cell cycle takes about 90 minutes

1) A and B 2) A and C 3) Only B 4) All are correct

74. Interval between mitosis and initiation of DNA replication is called

1) G₂ – Phase 2) G₁ – Phase 3) Karyokinesis 4) S – phase

75. Diploid cell in human, where cell division does not occur

a) Heart cell b) Muscle cell c) Nerve cell

1) Only c 2) b and c 3) a and c 4) a, b and c

76. The events shown below occur during different phases

A. Centromere splits, chromatidsseparate and move to opposite poles, chromatids are now celled chromosome

B. Chromosomes cluster at opposite poles, decondensation of chromosome, reappearance of NM, GB and ER

C. Chromosome are arranged at equatorial plate

D. Kinetochores are arranged at equatorial plate

E. Condensation of chromosomal materials

Which of the following correctly indentifies each of the phases described

	Interphase	Prophase	Metaphase	Anaphase	Telophase
1)	C	E	D	A	B
2)	C	D	E	A	B
3)	C	E	D	B	A
4)	C	A	D	E	B

77. Arrange the following events of meiosis in the correct sequence-

A. Terminalisation of chiasmata

B. Crossing over

C. Synapsis

D. Disjunction of chromosomes

E. Dissolution of synaptonemal complex

The correct sequence is-

1) A®B®C®D®E 2) E®D®C®B®A 3) C®B®D®E®A 4) C®B®E®A®D

78. The anaphase of mitosis differs from metaphase in:

 (a) Half the number of chromosomes

 (b) Half the number of chromatids in each chromosome

 (c) Half the number of chromosomes but doubles the number of chromatids in

each chromosome

 (d) Half the number of chromosomes and half the number of chromatids in each

chromosome.

79. Chromosome in equtorial plane is seen during

1) Metaphase of mitosis 2) Anaphase of mitosis

3) First anaphase of meiosis 4) Second anaphase of meiosis

80.  The correct sequence of Prophase I is

1) Diplotene>Pachytene>Diakinesis>Zygotene>Leptotene>Pre-leptotene

2) Leptotene>Pachytene>Diakinesis>Zygotene >Pre-leptotene> Diplotene

3) Leptotene >Diakinesis>Zygotene >Pre-leptotene> Diplotene> Pachytene

4) Pre-leptotene>Leptotene>Zygotene>Pachytene>Diplotene>Diakinesis

81. A cell has 46 chromosomes at each pole in mitotic telophase. In this division the number of chromatids at the metaphase was:-

1) 23 2) 46 3) 92 4) 69

82. A mouse cell is treated with a chemical that interferes with the activity of microfilaments. Which

of the following will probably be affected the most?

1) Formation of spindle fibres 2) Division of cytoplasm

3) Chromosome duplication 4) Pairing of homologous chromosomes

83. Number of chromosome pairs at equator in metaphase-I of a diploid plant cell (n=25

chromosomes) shall be-

1) 50 2) 100 3) 75 4) 25

84. How many meiotic divisions are required during the formation of 500 zygotes, if in males one

meiotic division results in formation of four male gametes and in females one meiotic division

results in formation of one female gamete?

1) 625 2) 500 3) 1000 4) 2500

85. Number of chromatids in each chromosome at anaphase is-

1) One in mitosis, one in meiosis-I and two in meiosis-II

2) One in mitosis, two in meiosis-I and one in meiosis-II

3) Two in mitosis, one in meiosis-I and two in meiosis-II

4) Two in mitosis, two in meiosis-I and two in meiosis-II

86. In which of the following stages of mitosis, chromosomes are most condensed?

1) Stage between the stage of cell plate formation and stage of DNA replication

2) Stage between the stage of centrioles separation  and stage of splitting of centromere

3) Stage between the stage of DNA replication and stage of initiation of condensation of

chromatin

4) Stage between the stage of metaphase plate formation and stage of decondensation of

chromosomes

87. If the cell had diploid or 2n number of chromosomes at G₁, after S phase the number of

chromosomes in the cell is?

1) 2 n 2) 4 n 3) n 4) 3n

88.Name the cell division  in A -Gamete formation and B-body growth   

1) A®Meiosis-II, B®Meiosis-I 2) A®Mitosis, B®Meiosis-I

3) A®Meiosis, B®Mitosis 4) A®Mitosis, B®Meiosis

89. In a diploid cell Before S-phase quantity of DNA is 20 pico gram (pg) in a diploid cell.What will be    the quantity of DNA in each daughter cell after meiosis I ?

1) 10 pg 2) 20 pg 3) 5 pg 4) 40 pg

90. How many cycles of nucleus division, DNA replication and division of centromere

take place respectively during meiosis :-

1) Three, Two, One 2) One, Two, Two 3) Two, Two, One 4) Two, One, One

 

 

 

 

 

 

 

KEY

1. 4) Splitting of centromere

2. 2) Tetraploid cell

3.     2) Pachytene 

4. 1) Animals 

5. 2) Centrifugal

6. 2) Meiosis and fertilisation

7.     2) A-iv, B-v, C-ii, D-i, E-iii

8. 3) Anther

9. 4) Spindle fibres

10. 4) Telophase

11. 1) Terminalisation 

12. 1) One

13. 1) Decondensation of chromatin

14. 2) Metaphase

15. 4) 16 (Sixteen)

16. 2) Metaphase 

17. 1) Leptotene 

18. 18.4) 1-DNA

19. 1) Prophase & metaphase  

20. 2) Two chromatid

21. 1) G₁ – phase

22. 3) Anaphase – II

23. 3) Diakinesis 

24. 4) Interphase 

25. 2) Disjunction

26. 1) Primary constriction

27. 2) transition of metaphase

28. 3) paired meiotic chromosomes

29.   4) Anaphase

30. 3) Anaphase

31. 2)Anaphase – II

32. 3) 8 and 8

33. 4) Exchange of genetic materials occurs only in meiosis

34. 4) Division of centromere

35.  1) Division of nucleus twice but replication of DNA only once

36. 2) Genetically different

37. 1) Diakinesis

38 .3) Formation of two nuclei

39. 1) Anaphase

39. 4) Telophase 

40. 1) Prophase

41. 4) All the above

42.    2) Metaphase 

43. 2) Synapsis

44. 4) Interphase 

45.  3) Zygotene 

46. 3) Leptotene,zygotene, pachytene, diplotene, diakinesis

47. 2) Prophase, Metaphase, Anaphase, Telophase

48 .4) 2n

49. 1) Late prophase

50. 1) G₁ – phase

51. 1) Two homologus chromosomes

52.  2) Zygotene  

53. 2) Late prophase

54. 4) Late Anaphase – Prophase

55. 4) Chromosomes move to the spindle equator and get aligned along equatorial plate in metaphase    

56. 4) Kinetochores

57. 1) It involves two stages of DNA replication, one before meiosis-I and another before meiosis-II

58. 1) Prophase – I

59. 3) Prophase I during meiosis

60. 1) Anaphase I

61. 1) G-1 stage followed by Mitosis

62. 2) Telophase Nuclear envelop reforms golgi complex reforms

63. 4) Bivalent 

64. 2) S 

65. 4) G₂ and M

66. 1) Amount of DNA doubles in each cell

67. 1)  Pachytene 

68 .2) Interphase

69. 2) twice the number of chromosomes and four times the amount of DNA

70. 3) b, a, c, d

71. 1) All are correct

72.  4) DNA synthesis phase – Doubling of number of chromosome in cell

73. 3) Only B

74. 2) G₁ – Phase

75. 4) a, b and c

76.

	Interphase	Prophase	Metaphase	Anaphase	Telophase
1)	C	E	D	A	B

77. 4) C®B®E®A®D

78.  (b) Half the number of chromatids in each chromosome

79.   3)First anaphase of meiosis

80. 4) Pre-leptotene>Leptotene>Zygotene>Pachytene>Diplotene>Diakinesis

81. 3) 92

82. 2) Division of cytoplasm

83. 4) 25

84. 1) 625

85. 2) One in mitosis, two in meiosis-I and one in meiosis-II

86.   2) Stage between the stage of centrioles separation  and stage of splitting of centromere

87. 1) 2 n

88. 3) A®Meiosis, B®Mitosis

89. 2) 20 pg

90. 4) Two, One, One