Class XI & XII · Biology practice
Zoology PYQs Check your understanding, bookmark questions and revisit your mistakes.
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407 questions in this collection · Page 28 of 41
Principles Of Inheritance And Variation
Under which of the following conditions will there
be no change in the reading frame of following
mRNA?
A Deletion of GGU from 7th , 8th and 9th positions B Insertion of A at G at 4th and 5th positions respectively C Deletion of G from 5th position D Insertion of G at 5th position
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Explanation: The reading frame is set by codons of three bases. The given mRNA has codons: AAC | AGC | GGU | GCU | AUU. Deleting an entire codon (GGU at positions 7–9) removes 3 bases, preserving the frame. Hence, no shift occurs with option 1.
🧠 Did You Know? Inserting or deleting any number of bases not divisible by three shifts the reading frame (frameshift), changing all downstream codons and potentially altering the protein.
💡 NCERT Memory Line: A reading frame is read in consecutive triplets; indels not in multiples of three cause frameshifts and alter the amino acid sequence.
Principles Of Inheritance And Variation
What is the genetic disorder in which an individual
has an overall masculine development, gynaecomastia and is sterile?
A Edward syndrome B Turner's syndrome C Klinefelter's syndrome D Down's syndrome
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Evolution
Variations caused by mutation, as proposed by Hugo
de Vries, are:
A random and directionless B random and directional C small and directional D small and directionless
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Evolution
n a species, the weight of newborn ranges from 2
to 5 kg. 97% of the newborn with an average weight
between 3 to 3.3kg survive whereas 99% of the
infants born with weights from 2 to 2.5 kg or 4.5
to 5 kg die. Which type of selection process is taking place?
A Stabilizing Selection B Directional Selection C Disruptive Selection D Cyclical Selection
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Evolution
Match the hominids with their correct brain size :
(A)Homo habilis
(I)900 cc
(B)Homo neanderthalensis
(II)1350 cc
(C)Homo erectus
(III)650-800 cc
(D)Homo sapiens
(IV)400 cc
Select the correct option.
A (A)-(III), (B)-(I), (C)-(IV), (D)-(II) B (A)-(III), (B)-(II), (C)-(I), (D)-(IV) C (A)-(III), (B)-(IV), (C)-(I), (D)-(II) D (A)-(IV), (B)-(III), (C)-(I), (D)-(II)
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Human Health And Disease
Identify the correct pair representing the causative agent of typhoid fever and the confirmatory test for typhoid.
A Salmonella typhi/Widal test B Salmonella typhi/Anthrone test C Streptococcus pneumoniae/Widal test D Plasmodium vivax/UTI test.
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Human Health And Disease
Concanavalin A is:
A an alkaloid B a lectin C an essential oil D a pigment
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Human Health And Disease
Which of the following immune responses is
responsible for rejection of kidney graft?
A Cell-mediated immune response B Inflammatory immune response C Humoral immune response D Cell-mediated immune response
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Human Health And Disease
Drug called 'Heroin' is synthesized by:
A methylation of morphine B glycosylation of morphine C acetylation of morphine D nitration of morphine
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Strategies For Enhancement In Food Production
What triggers activation of protoxin to active Bt toxin of Bacillus thuringiensis in boll worm?
A Body temperature B Moist surface of midgut C Acidic pH of stomach D Alkaline pH of gut
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