Class 12 Biology MCQs Chapter – 6
21. Two genes present near by on a chromosome will have :
( A ) Double crossing over
( B ) No crossing over
( C ) Hardly any crossing over
( D ) Regular crossing over
Answer-( C )
22. Exchange of segments between non- homologous chromosomes is called:
( A ) Crossing over
( B ) Inversion
( C ) Duplication
( D ) Translocation
Answer-( D )
23. Complete linkage has been reported in :
( A ) Maize
( B ) Human female
( C ) Female Drosophilla
( D ) Male Drosophilla
Answer-( D )
24. Genes are made up of :
( A ) Lipoprotein
( B ) Nucleosides
( C ) Polynucleotides
( D ) Histones
Answer-( C )
25. Triplet UUU codes for :
( A ) Leucine
( B ) Methionine
( C )Phenylalanine
( D ) Glycine
Answer-( C )
26. In gene mutation, adenine is replaced by guanine. It is :
( A ) Frame-shift mutation
( B )Transcription
( C ) Transition
( D ) Transversion
Answer-( C )
27. A segment of DNA that reads the same forward and backward is called:
( A ) palindromic DNA
( B ) Plasmimic DNA
( C ) complementary DNA
( D ) copy DNA
Answer-( A )
28. Purines of RNA are :
( A ) guanine and adenline
( B )uracil and thymine
( C ) adenine and cytosine
( D )uracil and guanine
Answer-( A )
29. Which one is correct for RNA ?
( A ) [A] = [U]
(B) [G] = [C]
( C ) [A] not equal [U]
( D ) [A] + [G]
Answer-( C )
30. Which is recognition site of RNA ?
( A ) Anticodon
( B ) Loop I
( C ) Loop IV
( D ) 3-OH end
Answer-( A )
31. RNA is synthesized on :
( A ) both strands of DNA
( B ) on sense strand of DNA
( C ) on complementary strand of DNA
( D ) on c DNA
Answer-( B )
32. If codon in DNA is AAA. What will be the anticodon for it :
( A )U U U
( B ) AAA
( C ) TTT
( D ) AUG
Answer-( B )
33. DNA fragments are joined by :
( A ) Ligase
( B ) Polymerase
( C ) Helicase
( D ) Gyrase
Answer-( A )
34. DNA and RNA differ by :
( A ) Nitrogen bases and sugars
( B ) Nitrogen bases and phosphate groups
( C ) Number of C-atoms in sugars
( D )Sugar and phosphate groups
Answer-( A )
35. Who discovered DNA polymerase
( A ) Okazaki
( B ) Kornberg
( C ) Meselson and Stahl
( D )Watson and Crick
Answer-( B )
36. Uracil is related to
( A ) RNA
( B ) DNA
( C ) Both ( A ) & ( D )
( D ) None of these
Answer-( A )
37. Lac operon represents
( A ) Inducible gene system
( B ) Repressible gene system
( C ) Housekeeping gene system
( D ) All of these
Answer- ( A )
38. Synthesis of RNA on DNA template is known as
( A ) Translation
( B ) Transcription
( C ) Transduction
( D ) Replication
Answer-( B )
39. Which of the following is a wrong pair ?
( A ) G ≡ C
( B ) T = A
( C ) A = U
( D ) T = U
Answer- ( D )
40. Genes present on same locus having different expression are called :
( A ) Multiple allele
( B ) Polygene
( C )
( D ) Codominant gene
Answer- ( A )
