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

12th Standard

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Biology

Answer all the questions

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

    Answer all the questions

    25 x 1 = 25
  1. The milk secreted by the mammary glands soon after child birth is called ______.

    (a)

    Mucous

    (b)

    Colostrum

    (c)

    Lactose

    (d)

    Sucrose

  2. A contraceptive pill prevents ovulation by ______.

    (a)

    blocking fallopian tube

    (b)

    inhibiting release of FSH and LH

    (c)

    stimulating release of FSH and LH

    (d)

    causing immediate degeneration of released ovum.

  3. Which of the following is true about Rh factor in the offspring of a parental combination DdxDd (both Rh positive)?

    (a)

    All will be Rh-positive

    (b)

    Half will be Rh positive

    (c)

    About ¾ will be Rh negative

    (d)

    About one fourth will be Rh negative

  4. Which of the following statements about DNA replication is not correct?

    (a)

    Unwinding of DNA molecule occurs as hydrogen bonds break.

    (b)

    Replication occurs as each base is paired with another exactly like it

    (c)

    Process is known as semi conservative replication because one old strand is conserved in the new molecule.

    (d)

    Complementary base pairs are held together with hydrogen bonds

  5. According to Darwin, the organic evolution is due to

    (a)

    Intraspecific competition

    (b)

    Interspecific competition

    (c)

    Competition within closely related species.

    (d)

    Reduced feeding efficiency in one species due to the presence of interfering species.

  6. AIDS virus has

    (a)

    Single stranded RNA

    (b)

    Double stranded RNA

    (c)

    Single stranded DNA

    (d)

    Double stranded DNA

  7. Corn \(\overset { A }{ \rightarrow } \) Fermentable sugars \(\overset { B }{ \rightarrow } \) Ethanol. Find out A and B for above statement.

    (a)

    A - Agaricus, B - Sarcina

    (b)

    A - Zymomonas, B - Vinegar

    (c)

    A - Rhizopus, B - Aspergillus

    (d)

    A - Aspergillus, B - Yeast

  8. Transgenic animals are those which have

    (a)

    Foreign DNA in some of their cells

    (b)

    Foreign DNA in all their cells

    (c)

    Foreign RNA in some of their cells

    (d)

    Foreign RNA in all their cells

  9. Bacillus thuringiensis forms protein crystals which contain insecticidal protein. This protein

    (a)

    Binds with epithelial cells of midgut of the insect pest ultimately killing it.

    (b)

    Is coded by several genes including the gene cry.

    (c)

    Is activated by acid pH of the foregut of the insect pest.

    (d)

    Does not kill the carrier bacterium which is itself resistant to this toxin.

  10. Which of the following is correct for r-selected species

    (a)

    Large number of progeny with small size

    (b)

    large number of progeny with large size

    (c)

    small number of progeny with small size

    (d)

    small number of progeny with large size

  11. Identify the incorrect statement

    (a)

    Water is a universal solvent

    (b)

    Water has less surface tension

    (c)

    Water is heavier than air

    (d)

    When freezes water contracts

  12. Select the proper sequence indicating the increasing order of biodiversity.

    (a)

    Polar, Temperate and Polar

    (b)

    Tropics, Temperate and Polar

    (c)

    Temperate, Tropic and Polar

    (d)

    Polar, Tropic and Temperate

  13. The Hydrochlorofluorocarbons (HCFCs) are the compounds which have the following molecules:

    (a)

    Hydrogen

    (b)

    Carbon

    (c)

    Chlorine

    (d)

    Fluorine

  14. Average human consumption of oxygen per day is_________

    (a)

    280 L

    (b)

    550 L

    (c)

    620 L

    (d)

    730 L

  15. Assertion (A): Carica papaya is a dioecious plant.
    Reason (R): Both male and female flowers are borne on same plant.

    (a)

    A is correct R is incorrect.

    (b)

    R explains A.

    (c)

    Both A and R are incorrect.

    (d)

    Both A and R are correct. R does not explain A.

  16. Test cross involves ____.

    (a)

    Crossing between two genotypes with recessive trait

    (b)

    Crossing between two F1 hybrids

    (c)

    Crossing the F1 hybrid with a double recessive genotype

    (d)

    Crossing between two genotypes with dominant trait

  17. Assertion (A): Test cross is done between F2 hybrid with F1 recessive
    Reason (R): It helps to identify the homozygosity of hybrids

    (a)

    A and R are correct R explains A

    (b)

    A and R are incorrect

    (c)

    A is correct R is incorrect

    (d)

    A is incorrect R is correct

  18. At which stage of meiosis, does the chromosomes undergo recombination process

    (a)

    Leptotene stage of prophase I

    (b)

    Zygotene stage of prophase I

    (c)

    Diplotene stage of prophase I

    (d)

    Pachytene stage of prophase I

  19. Self-ligation is prevented by____________

    (a)

    DNA Polymerase

    (b)

    Helicase

    (c)

    Alkaline phosphate

    (d)

    DNA lipase

  20. Which of the following plant has a non-succulent xerophytic and thick leathery leaves with waxy coating

    (a)

    Bryophyllum

    (b)

    Ruscus

    (c)

    Nerium

    (d)

    Calotropis

  21. Identify the incorrect statement

    (a)

    Carbon stored in oil is referred as Grey carbon

    (b)

    Carbon stored in atmosphere is referred as Blue carbon

    (c)

    Carbon stored in industrialized forests is referred as Green carbon

    (d)

    Carbon emitted from gas, died engine is referred as Black carbon

  22. The unit for measuring ozone thickness _____.

    (a)

    Joule

    (b)

    Kilos

    (c)

    Dobson

    (d)

    Watt

  23. Which is not a true statement regarding rainwater harvesting?

    (a)

    Mitigates groundwater quality

    (b)

    Reduces soil erosion

    (c)

    Decreases soil salinity

    (d)

    No wastage of land for storing

  24. The term green revolution was coined by ___________

    (a)

    William S Gaud

    (b)

    M.S. Swaminathan

    (c)

    Dr. B.P. Pal

    (d)

    Dr. N.E. Borla

  25. Identify the tamil name for flaked rice

    (a)

      Nel

    (b)

    Aval  

    (c)

    Pori

    (d)

    Umi

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