biology-today_2015-03

Assertion & reason

In each of the following questions, a statement of
Assertion (A) is given and a corresponding statement

of Reason (R) is given just below it. Of the statements,
mark the correct answer as :
(a) if both A and R are true and R is the correct explanation

of A

(b) if both A and R are true but R is not the correct

explanation of A

(c) if A is true but R is false

(d) if both A and R are false.

29. Assertion : DNA replication in prokaryotes is
    semiconservative, semicontinuous and bidirectional.

Reason : DNA replication in eukaryotes is
semiconservative, bidirectional and continuous.

30. Assertion: The primary transcript of mRNA is called
    heterogeneous nuclear RNA or hnRNA.

Reason : hnRNA is often larger than the functional
RNA.

31. Assertion : Codon is found in both DNA and mRNA.

Reason : Codon determines the position of a gene in
the DNA.

32. Assertion : Both RNA and DNA are feulgen
    negative.

Reason : Base pairing through hydrogen bonds occurs

only in DNA and never in RNA.

33. Assertion : A lot of energy is consumed during protein
    synthesis.

Reason : For every single amino acid incorporated

in the peptide chain, 2 ATP and 1GTP molecules are

used.

34. Assertion : Out of the two strands of DNA, only
    one strand is effective in producing mRNA in a given
    cistron.

Reason : It is called antisense strand.

35. Assertion : Aporepressor is a proteinaceous substance
    synthesised by regulator gene.

Reason : By itself, the aporepressor is unable to block

the working of operator gene.

36. Assertion : Human gene count is about the same, as
    that of the mouse.

Reason : Nine tenth of genes are identical to that of

the mouse.

37. Assertion : VNTRs are ‘variable number tandem
    repeats which are inherited by an individual from his
    parents.
    Reason : They are also called ‘microsatellites’ and are
    used as genetic markers in personal identity test.


38. Assertion : A peptide bond (–CO–NH–) is established
    between the amino group (–NH 2 ) of amino acid at P site,
    and carboxyl group (–COOH) of amino acid at A-site.
    Reason : Peptide bond formation during translation is
    catalysed by peptidyl transferase, a protein enzyme.

Figure Based Questions

39. Refer the given figure and identify the labelled parts
    P, Q, R, S and T.


40. Fill in the blanks using the letters assigned to figure in
    previous question.
    (a) has 7 bases out of which 3 bases form
    anticodon or nodoc, for attaching to codon of
    mRNA.
    (b) lies at 3’ end, opposite the anticodon.
    (c) has 7 bases and forms site for attaching
    to ribosome.
    (d) is the largest loop and is binding site for
    aminoacyl synthetase enzyme.
    (e) _____ is not present in all tRNAs, and its exact
    role is not known.