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BIOLOGY Assertion (A) & Reason (B) MCQ

MODEL PAPER 8 · Rajasthan Board (RBSE) STD 12 Science (Rajasthan - English Medium). 4 questions.

Questions

Assertion (A) & Reason (B) MCQ

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4 questions · self-marked practice — reveal the answer and mark yourself.

MCQ 11 Mark
Assertion (A): Generally, a woman does not conceive during the lactation period.
Reason (R): The hormone prolactin initiates and maintains lactation in a woman.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • C
    A is true but R is false.
  • D
    A is false but R is true.
Answer
Both A and R are true and R is the correct explanation of A.
Explanation: Both A and R are true and R is the correct explanation of A.
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MCQ 21 Mark
Assertion (A): Griseofulvin extracted from P. griseofulvum is used for ringworm treatment.
Reason (R): Trichophyton, Epidermophyton, etc. cannot grow well in presence of Penicillium griseofulvum.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • C
    A is true but R is false.
  • D
    A is false but R is true.
Answer
Both A and R are true and R is the correct explanation of A.
Explanation: Antibiotics are chemical substances produced by some microbes which in small concentration can kill or retard the growth of harmful microbes without adversely affecting the host. Griseofulvin is an antibiotic produced by Penicillum griseofulvum and is antifungal in nature, especially effective against ringworm. Ringworm is caused by dermatophytic fungi like Epidermophyton, Trichophyton, Microsporium, etc. which cannot grow in presence of P. griseofulvum because of the antagonistic effect of antibiotic griseofulvin secreted by it.
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MCQ 31 Mark
Assertion (A): Most evolutionary trees place information about pattern of relationship on horizontal axis and time on vertical axis.
Reason (R): An evolutionary tree depicts pattern of relationship among parents and offsprings.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • C
    A is true but R is false.
  • D
    A is false but R is true.
Answer
A is true but R is false.
Explanation: A is true but R is false.
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MCQ 41 Mark
Assertion (A): Autotrophs are also called as transducers.
Reason (R): They change one form of energy into another.
  • A
    Both A and R are true and R is the correct explanation of A.
  • B
    Both A and R are true but R is not the correct explanation of A.
  • C
    A is true but R is false.
  • D
    A is false but R is true.
Answer
Both A and R are true and R is the correct explanation of A.
Explanation: Autotrophs are those plants which are able to synthesise organic food from inorganic raw materials with the help of solar radiations. They are also called as transducers because they are capable to change light energy into chemical energy (organic food).
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