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12th Standard Biology English Medium Free Online Test One Mark Questions with Answer Key 2020 - Part Three

12th Standard

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Biology

Time : 00:25:00 Hrs
Total Marks : 25

    Answer all the questions

    25 x 1 = 25
  1. Assertion and reasoning questions:
    In each of the following questions there are two statements. One is assertion (A) and other is reasoning (R). Mark the correct answer as
    Assertion: Offsprings produced by asexual reproduction are genetically identical to the parent.
    Reason: Asexual reproduction involves only mitosis and no meiosis

    (a)

    both A and R are true and R is correct explanation for A

    (b)

    If both A and R are true but R is not the correct explanation for A

    (c)

    If A is true but R is false

    (d)

    If both A and R are false.

  2. Assertion (A): Asexual reproduction is called blastogenic reproduction.
    Reason (R): It is accomplished by mitotic and meiotic divisions.

    (a)

    A and R are correct

    (b)

    A is correct but R is incorrect

    (c)

    Both A and R are incorrect

    (d)

    R is the correct explanation for A

  3. The most important hormone in intiating and maintaining lactation after birth is

    (a)

    Oestrogen

    (b)

    FSH

    (c)

    Prolactin

    (d)

    Oxytocin

  4. Select the incorrect action of hormonal contraceptive pills from the following

    (a)

    Inhibition of spermatogenesis.

    (b)

    Inhibition of ovulation

    (c)

    Changes in cervical mucus impairing its ability to allow passage and transport of sperms

    (d)

    Alteration in uterine endometrium to make it unsuitable for implantation

  5. Which of the following approach does not give the defined action of contraceptive?

    (a)
    a) Barrier methods Prevent fertilizers

     

    (b)
    b) Intra uterine devices Increases phagocytosis of sperms suppresses sperm motility and fertilizing capacity of sperms. 

     

    (c)
    c) Hormonal contraceptives Prevent retard entry of sperms, prevent ovulation and fertilization.

     

    (d)
    d) Vasectomy Prevents spermatogenesis

     

  6. Mangolism is a genetic disorder which is caused by the presence of an extra chromosome number

    (a)

    20

    (b)

    21

    (c)

    4

    (d)

    23

  7. Which one of the following cannot be explained on the basis of Menders Law of Dominance?

    (a)

    The discrete unit controlling a particular character is called a factor

    (b)

    Out of one pair factors one is dominant and the other recessive

    (c)

    Alleles do not show any blending and both the characters recover as such in F2 generation

    (d)

    Factors occur in pairs

  8. E. coli cell grown on 15N medium are transferred to 14N medium and allowed to grow for two generations. DNA extracted from these cells is ultracentrifuged in a cesium chloride density gradient. What density distribution of DNA would you expect in this experiment?

    (a)

    One high and one low density band

    (b)

    One intermediate density band.

    (c)

    One intermediate density band.

    (d)

    One low and one intermediate density band

  9. The association of histone H1 with a nudeosome indicates

    (a)

    Transcription is occurring

    (b)

    DNA replication is occurring

    (c)

    The DNA is condensed into chromatin fiber

    (d)

    The DNA double helix is exposed

  10. The phenomenon of “ Industrial Melanism” demonstrates

    (a)

    Natural selection

    (b)

    induced mutation

    (c)

    reproductive isolation

    (d)

    geographical isolation

  11. Peripatus is the connection link between Annelida and _______________

    (a)

    Arthropoda

    (b)

    Platyhelminthes

    (c)

    Mollusca

    (d)

    Echinodermata

  12. Which of the following is/are not examples of analogous structure
    (a) Wings of Birds and Bats
    (b) Wings of Birds and Insects
    (c) Thorn of Bougainvillea and Tendril of Cucurbita
    (d) Flippers of Penguins and Dolphins

    (a)

    a, b, c

    (b)

    a and c

    (c)

    band d

    (d)

    All the above

  13. The Athlete’s foot disease in human is caused by _______

    (a)

    Bacteria

    (b)

    Fungi

    (c)

    Virus

    (d)

    Protozoan

  14. Choose the symptom applicable for mumps

    (a)

    Muscular stiffness

    (b)

    Enlargement of parotid gland

    (c)

    Flu like illness

    (d)

    Respiratory failure

  15. The incubation period of malaria' is_______days.

    (a)

    10

    (b)

    12

    (c)

    15

    (d)

    18

  16. Which one of the following pairs is wrong.

    (a)

    Amoebiasis - Home fly

    (b)

    African sleeping sickness - Tsetse flies

    (c)

    Kala-azar - Sand fly

    (d)

    Malaria - female Anopheles mosquito

  17. The test that confirms HIV positive is ________________

    (a)

    Western blot

    (b)

    Northern blot

    (c)

    Southern blot

    (d)

    all the above

  18. Which of the following is not involved in nitrogen fixation?

    (a)

    Pseudomonas

    (b)

    Azotobacter

    (c)

    Anabaena

    (d)

    Nostac

  19. __________is free living bacteria which acts as a biofertilizer.

    (a)

    Azospirillum

    (b)

    Nostoc

    (c)

    Oscillatoria

    (d)

    Glomus

  20. Which of the following are likely to be present in deep-sea water?

    (a)

    Archaebacteria

    (b)

    Eubacteria

    (c)

    Blue-green algae

    (d)

    Saprophytic fungi

  21. Name the person who was the first to use the term antibiotic

    (a)

    Selman Waksman

    (b)

    Alexander Flemming

    (c)

    Earnest Chain

    (d)

    Howard Florey

  22. Predation and parasitism are which type of interactions?

    (a)

    (+,+)

    (b)

    (+, O)

    (c)

    (--, --)

    (d)

    (+, --)

  23. Which of the following forests is known as the lungs of the planet earth?

    (a)

    Tundra forest

    (b)

    Rain forest of north east India

    (c)

    Taiga forest

    (d)

    Amazon rain forest

  24. Depletion of which gas in the atmosphere can lead to an increased incidence of skin cancer?

    (a)

    Ammonia

    (b)

    Methane

    (c)

    Nitrous oxide

    (d)

    Ozone

  25. Plants having similar genotypes produced by plant breeding are called

    (a)

    clone

    (b)

    haploid

    (c)

    autopolyploid

    (d)

    genome

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