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12th Standard Biology English Medium Chromosomal Basis of Inheritance Reduced Syllabus Important Questions 2021

12th Standard

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Biology

Time : 01:00:00 Hrs
Total Marks : 100

    Multiple Choice Questions

    15 x 1 = 15
  1. The A and B genes are 10 cM apart on a chromosome. If an AB/ab heterozygote is testcrossed to ab/ab, how many of each progeny class would you expect out of 100 total progeny?

    (a)

    25 AB, 25 ab, 25 Ab, 25 aB

    (b)

    10 AB, 10 ab

    (c)

    45 AB, 45 ab

    (d)

    45 AB, 45 ab, 5 Ab, 5aB

  2. Accurate mapping of genes can be done by three point test cross because increases

    (a)

    Possibility of single cross over

    (b)

    Possibility of double cross over

    (c)

    Possibility of multiple cross over

    (d)

    Possibility of recombination frequency

  3. Due to incomplete linkage in maize, the ratio of parental and recombinants are

    (a)

    50:50

    (b)

    7:1:1:7

    (c)

    96.4: 3.6

    (d)

    1:7:7:1

  4. How many map units separate two alleles A and B if the recombination frequency is 0.09?

    (a)

    900 cM

    (b)

    90 cM

    (c)

    9 cM

    (d)

    0.9 cM

  5. Which is not a feature of the chromosomal theory of inheritance?

    (a)

    Somatic cells of organisms are derived from zygote by repeated meiosis.

    (b)

    Chromosomes retain their structural uniqueness throughout the life of an organism.

    (c)

    Mendelian factors are located in chromosomes

    (d)

    Sutton and Boveri independently proposed the theory.

  6. The following sequence represents the location of genes in a chromosome. A - B - C - M - R - S - y -Z. Which of the gene pairs will have least chance of getting inherited together?

    (a)

    A and M

    (b)

    Sand Y

    (c)

    M and Z

    (d)

    A and Y

  7. Which of the following statement(s) is/are wrong with respect to Recombination process?
    (i) Mitotic crossing over occurs rarely in somatic cells.
    (ii) Syndesis refers to pairing of non-homologous chromosome.
    (iii) Procentric synapsis starts from telomeres.
    (iv) A Bivalent has four chromatids.

    (a)

    i and iv

    (b)

    ii and i

    (c)

    ii and iii

    (d)

    All the above

  8. Mutation theory was proposed by____________

    (a)

    T. H. Morgan

    (b)

    Hugo de Vries

    (c)

    Alfred Sturtevant

    (d)

    Sutton and Boveri

  9. Transition type of gene mutation is caused when__________

    (a)

    AC is replaced by GT

    (b)

    AG is replaced by TC

    (c)

    AC is replaced by TG

    (d)

    TC is replaced by AG

  10. Sharbati Sonara is a mutant wheat variety which is developed by irradiating the seeds with _________

    (a)

    Thermal neutrons

    (b)

    Gamma radiation

    (c)

    X-rays

    (d)

    UV radiations

  11. Statement 1: Euploidy involves entire sets of chromosomes
    Statement 2: Aneuploidy involves individual chromosomes within a diploid net.

    (a)

    Statement 1 is correct and Statement 2 is incorrect

    (b)

    Statement 1 is incorrect and Statement 2 is correct

    (c)

    Both the statements are correct

    (d)

    Both the statements are incorrect

  12. Statement 1: In transversion mutation, single purine is changed to pyrimidine.
    Statement 2: In transition mutation, a purine replaced by another purine.

    (a)

    Statement 1 is correct and Statement2 is incorrect

    (b)

    Statement 1 is incorrect and Statement 2 is correct

    (c)

    Both the statements are correct

    (d)

    Both the statements are incorrect

  13. One of the following is not the kind of euploidy

    (a)

    Diploidy

    (b)

    Polyploidy

    (c)

    Hyperploidy

    (d)

    Autoploidy

  14. Assertion (A): Self-sterility is observed in Nicotiana species.
    Reason (R): Because the genes are located on chromosome.

    (a)

    A is true R is false

    (b)

    Both A and R are false

    (c)

    A is true, R is not correct explanation for A

    (d)

    R explains A

  15. Observe the gene sequence and identify the types of aberration ABC BCD E F?

    (a)

    Tandem duplication

    (b)

    Simple duplication

    (c)

    Reverse tandem duplication

    (d)

    Displaced tandem duplication

  16. 2 Marks

    10 x 2 = 20
  17. If you cross dominant genotype PV/PV male Drosophila with double recessive female and obtain F1 hybrid. Now you cross F1 male with double recessive female.
    i) What type of linkage is seen?
    ii) Draw the cross with correct genotype.
    iii) What is the possible genotype in F2 generation?

  18. s.no gamete types Number of progenies
    1 ABC 349
    2 Abc 114
    3 abC 124
    4 AbC 5
    5 aBc 4
    6 aBC 116
    7 ABc 128
    8 abc 360

    i) What is the name of this test cross?
    ii) How will you construct gene mapping from the above given data?
    iii) Find out the correct order of genes.

  19. Define linkage. Mention its types.

  20. What are linked genes?

  21. What are bivalents? When does this condition is noticed in a cell?

  22. Define terminalization.

  23. What is genetic mapping?

  24. Name any four chemical mutagens.

  25. What is ploidy?

  26. Given below are the gene sequences on the chromosome. Compare them with the normal  chromosome and identify the type of structural chromosomal aberrations.
    Normal Chromosome : A - B - C - D - E- F - G - H - I.
    Chromosome 1 : A - B - C - B .•C - D - E - F - G - H - I.
    Chromosome 2 : A - B - C - D - F - G - H - I

  27. 3 Marks

    10 x 3 = 30
  28. Write the salient features of Sutton and Boveri concept.

  29. Explain the mechanism of crossing over.

  30. State Coupling and Repulsion theory.

  31. How crossing over differs from linkage?

  32. What is recombination? Which is the widely accepted model of DNA recombination

  33. Enumerate the uses of Genetic mapping.

  34. Differentiate Missense mutation from Nonsense mutation.

  35. Name the following chromosomal conditions.
    (a) 2n + 2 + 2
    (b) 2n - 1 - 1
    (c) x
    (d) 2n
    (e) 2n + n + n
    f) 2n + 1

  36. Given below is a sequence of alphabets representing the genes of chromosome. Observe
    it and answer the questions.
    A- B - C - D - E - F - G - H - I - J -K.
    (a) Write the sequence of genes after the chromosome undergoes terminal deletion of single gene.
    (b) What will be the gene sequence, if the genes Eand Fundergoes tandem duplication?
    (c) Consider the centromere is located between the genes F and G and write a gene sequence, after paracentric inversion occurs in between the genes C, D and E.

  37. In Drosophila melanogaster, there are four pairs of chromosomes. If there occurs chromosomal aberrations resulting in trisomic and monnsomlc condition, what will be the chromosomal count? Write the correct chromosomal count against respective chromosomal aberration.

  38. 5 Marks

    7 x 5 = 35
  39. How sex is determined in monoecious plants. write their genes involved in it.

  40. What is gene mapping? Write its uses

  41. Draw the diagram of different types of aneuploidy.

  42. Why crossing over is important?

  43. Draw a Howchart depicting the various types of ploidy.

  44. List out the significance of ploidy.

  45. Explain the Translocation type of chromosomal aberration.

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