- ·· ·-'~ "~ ;

152 m:rD CBSE Champion Biolo

gy Ci.11112
8. Origin of replication of DNA In E.coli Is shown below. ill.. at the 5' end, and lill.. at the 3' end. At thes·
ldenllfy the labelled parts (I), (Ii), (Ill) and (Iv).
the most distinctive specialised end nucle0 ti cl1d
de .(j"
is added and a sequence of about 200 li.Yl_ . ' IJ}
to the 3' end. is added
(a) (i) initiator codon (ii) promotor

(a)
«~
(Iv) (111)
(i)- Discontinuous synthesis, (ii)- Continuous
synthesis (iii) 3' end (iv) S' end
(iii) terminator codon (Iv) release factors
(bl (i) promotor (Ii) elongation
(iii) regulation (Iv) termination
(c) (i) capping (ii) polyadenylation
(iii) mGPPP (iv) Poly A
(d) (i) repressor (ii) co-repressor
(b) (i)- Continuous synthesis, (ii)- Discontinuous (iii) operon (iv) release factors (Term I, _
2021 2
synthesis (iii) S' end (Iv) 3' end 13, Transcrip 10n urn 1s represented in the d. ~
. t ' 't '
(c) (i)- Discontinuous synthesis, (ii)- Continuous 1agrarn
given below.
synthesis (iii) S' end (iv) 3' end
3'
(d) (i)- Continuous synthesis, (ii)- Discontinuous
synthesis (iii) 3' end (iv) S' end r.!'1 S'
(I) Site
(Term/, 2021-22) L.!!.J
(111)
5.5 Transcription Identify site (I), factor (ii) and enzyme (iii) responsible
for carrying out the process.
(a) (i) Promoter site, (!il Rho factor (iii) RNA
9. Assertion : Ribosomal RNA Is synthesized in the
polymerase
nucleus of the cell.
Reason : It is translated with the enzyme RNA (b) (i) Terminator site, (11) Sigma factor (iii) RNA
polymerase 111. polymerase
(a) Both A and R are true and R is the correct (c) (i) Promoter site, (ii) Sigma factor (iii) RNA
explanation of A. polymerase
(b) Both A and R are true and R is not the correct (d) (i) Promoter site, (ii) Sigma factor (iii) DNA
explanation of A. polymerase (Term/, 2021-22)@
(c) A is true but R is false.
(d) A is false but R is true. (2023-24)~
·Mf+W (5 marks)
10. The promoter site and the terminator site for 14. Observe the segment of mRNA given below.
transcription are located at ✓_/ J' mRNA
(a) 3' (downstream) end and 5' (upstream) end,
respectively of the transcription unit
(b) S' (upstream) end and 3' (downstream) end, Exon
respectively of the transcription unit
5'
(c) the 5' (upstream) end of the transcription unit
(d) the 3' (downstream) end of the transcription (a) Explain and illustrate the steps involved tomak!
unit. (Term I, 2021-22) (]j fully processed hnRNA.
(b) Gene encoding RNA Polymerase I and III hll~
11. Which of the following is correct about mature RNA
been affected by mutation in a cell. Explain ill
in eukaryotes?
impact on the synthesis of polypeptide, stat~
(a) Exons and introns do not appear in the mature
RNA. reasons. (2022-23)~
(b) Exons appear, but introns do not appear in the
mature RNA. 5.6 Genetic Code
(c) lntrons appear, but exons do not appear in the
mature RNA. ■Mi-■ - - -- ------- ---
(d) Both exons and introns appear in the mat~ 15. What is the smallest part of a DNA molecule that<~'
RNA. (Term I, 2021-22) U!J be changed by a point mutation?
12. Two important RNA processing events lead to {a) . Ollgonucleotlde {b) Codon
specialised end sequences in most human mRNAs: (c) Gene (d) Nucleotide 1
(2023-24M
 Basis of /nherilonce 151
,AolclllI0r

~i ~.:: .::-~& =f iih l~:__ (a) A Is having 2'-0H group which makes it less
7
5,1 The DNA

-
reactive and structurally stable, wherecJs B is
having 2'-H group which makes it more reactive
A short piece of DNA, having 20 base pairs, was and unstcJble.
1. (b) A is having 2'-0H group which makes it more
analyzed to find the number of nucleotide bases
recJctive and structurally unstable, whereas B is
In each of the polynucleot lde strands. ·Some of the
having 2'-H group which makes it less reactive
results are shown in the table.
and structurally stable.
Number of nucleotide bases
- Adenine Cytosine Guanine Thymine
(c) A and B both have -OH groups which make it
more reactive and structurally stable.
Strand 1 4 4 (d) A and B both are having-OH groups which make
5 It less reactive and structurally stable.
(Term I, 2021-22) ~
Strand 2
How many nucleotides containing adenine were
present in strand 2? 5.2 The Search for Genetic Mate rial
(al 2 (b) 4 (c) 5 (d) 7
(2023-24) (]j ■Mi••
5. Which of the following criteria must a molecule fulfil
2. Total number of nucleotide sequences of DNA that
to act as a genetic material?
codes for a hormone is 1530. The proportion of
(i) It should not be able to generate its replica.
different bases in the sequence is found to be adenine
(ii) It should chemically and structurally be stable.
= 34%, guanine = 19%, cytosine = 23%, thymine
(iii) It should not allow slow mutation.
=19%.
(iv) It should be able to express itself in the form of
Applying Chargaff's rule, what conclusion can be
Mendelian characters.
drawn? (a) (i) and (ii) (b) (ii) and (iii)
(a) It is a double stranded circular DNA. (c) (iii) and (iv) (d) (ii) and (iv)
(bl It is a single stranded DNA. (Term I, 2021-22) (]j
(cl It is a double stranded linear DNA.
(d) It is a single stranded DNA coiled on histones. 6. Oswald Avery, Colin Macleod and Maclyn McCarty
used enzymes to purify biochemicals such as
(Term I, 2021-22) IBrr]
proteins, DNA and RNA from the heat-killed S cells
J. A stretch of an euchromatin has 200 nucleosomes-. to see which ones could transform live R cells into S
How many base pairs will there be in the stretch and cells in Griffith's experiment. They observed that
what would be the length of the typical euchromatin? (a) proteases and RNases affected transformation
(a) 20,000 bp and 13,000 x 10-9 m (b) DNase inhibited transformat ion
(b) 10,000 bp and 10,000 x 10·9 m (c) proteases and lipases affected transformat ion
(c) 40,000 bp and 13,600 x 10·9 m (d) RNases inhibited transformation.
(d) 40,000 bp and 13,900 x 10· 9 m (Term I, 2021-22) (]J
(T~rm I, 2021-22) IBrr]
5.4 Replication
4. Observe structures A and B given below. Which of
the following statements are correct?
S' 5' 7. If Meselson and Stahl's experiment is continued
Ho
1,yo~?H Hofyo~?H for sixth generations in bacteria, the ratio of heavy
strands 15N/15N :Hybrid 15 N/14N : light
14Nf14N
4' C H
1\c-c H/11' 1\~3' 2 71fr~ 1'
/3' 2' / I
4' C
1 containing DNA In the sixth generation would be
H c-c H H H (a) 1:1:1 (b) 0:1:7
I I I I (c) 0:1:15 (d) 0:1:31.
OH OH OH H
B (Term I, 2021-22} ~
A
 148 ~ CBSE Champion Biolo
gy Cia11ll
75. During elongation process of translation, th
A'f.11• (3 marks_) bond formation between amino acids is cat;PePlid!
65. (i) How many types of RNA polymerases are there
(a) ribosomal RNA (b) transfer RN/sed ~
in a eukaryote cell? Mention which one of them
(c) messenger RNA (d) small nuclear RNA,
transcribes hnRNA.
(ii) Write the changes that hnRNA undergoes (Term I, 2021.22)!1
before it leaves the nucleus as mRNA. !.
(2023) @
76. Give an example of a codon having dual r .
66. Construct and label a transcription unit from which unct1°'1.
the RNA segment given below has been transcribed. (Delhi 201 6JfR
Write the complete name of the enzyme that 77. How does a degenerate code differ from !
transcribed this RNA. unambiguous one? (Foreign ~
201
ATGCATGCATG C
■ • (2 mar~~l
•-:fi•t•■ - - ---- ·-
5,_l'---'-1. . :. . 1_,_I___,_l_l:___:_I
. .:. . I---'-1"""""1_1:........:....I_ 3,
"RNA molecule" 78. State a functional difference between the roi~ -
codons. ~
(Delhi 2019) ~
(a) AUG and UM
Mia■ I? marks) - - -- - - - - -- - · (b) Specific and Degenerate (2020)~
6 7. Name the different types of RNA polymerases in a 79. Differentiate between the genetic codes given belaw•
eukaryotic cell. Write their roles in transcription. (a) Unambiguous and Universal ·
(2020C) (b) Degenerate and Initiator (Al20t~
68. Name the type of cells and the process by 80. Following are the features of genetic codes. What
which hnRNA is formed. Describe the processing does each one indicate?
mechanism it undergoes before it becomes Stop codon; Unambiguous codon; Degeneratecodort
functional. (2020)@
Universal codon. (Al 2016)~
69. Compare the processes of DNA replication and
transcription in prokaryotes. (2019 C) MEW (5 marks)
70. (a) Describe the process of transcription in bacteria. 81. (a) Write the contributions of the following
(b) Explain the processing the hnRNA needs to scientists in deciphering the genetic code.
undergo before becoming functional mRNA of George Gamow; Hargobind Khorana; Marshal
eukaryotes. (Al 2016) Nirenberg; Severo Ochoa
71. Explain the process of transcription in prokaryotes. (b) State the importance of a genetic code in protein
How is the process.different in eukaryotes? biosynthesis. (Delhi 201~
(A/2015) @ 82. (a) Describe the structure and function of a tRNA
72. Explain the process of transcription in eukaryotes. molecule. Why is it referred to as an adaptg
• (Foreign 2015) molecule?
(b) Explain the process of splicing of hnRNA in;
5.6 Genetic Code eukaryotic cell. (Al 201~

5.7 Translation
73. Given below is a sequence of bases in mRNA of a
bacterial cell. Identify the amino acid that would be
incorporated at codon position 3 and codon position 83. The different types of RNAs transcribed by R~~
5 during the process of its translation. polymerase Ill in eukaryotes are
3' AUCAGGUUUGUGAUGGUACGA S' (a) tRNA, hnRNA, 285 rRNA
(a) Phenylalanine, Methionine
(b) 28S rRNA, 18S rRNA, 5.8S rRNA
(b) Cysteine, Glycine
(c) tRNA, 5S rRNA, snRNAs
(c) Alanine, Proline
(d) hnRNA, 18S rRNA, 28S rRNA. ~•
(d) Serine, Valine (2023) (h) .??I i
(Tierm I, 2021 -- --
74. When an amino acid is coded by more than one
codon, the genetic code is said to be WJ.f;lljl mark)
(a) universal (b) punctuated 84· Write the two ~-p ecific codons that a translati(#
(c) commaless (d) degenerate.
unit of mRNA is flanked by one on ei ther sides. ·c
(Term I, 2021-22)@ (Al 201,
 147
Basis of Inheritance
1Aolecu Ior
Name the st age in cell cycle where DNA (d) Determines the first nucleotide to be t ranscribe~
47 (a)
replication occur. Into RNA. (Term 1. 2021 -22J U
(bl Explain the mechanism of DNA replication.
Highlight the role o f enzymes In t he process. 55 In a transcriptio n unit In DNA the 'I' is located
(c) Why Is DNA replication said t o be semi - towards 3' end of the 'II' strand and it usually defines
conscrvaliv e? (A l 20 16J u... the end of the process o f transcriptio n.
Choose the correct I and II from the opt ions given
that was
48. Describe M esc lson and Stahl's experiment below.
carried in 1958 on E. coli. Write the conc lusion they Promoter. template
(a) Terminator. coding (b)
arrived at aft er the experiment . (Al 2016J
(c) rho fact or, template (d) sigma factor, coding
a labelled diagram of a "replicating fork"
49. (a) Draw (Term 1, 2021-22) (LJJ
showing the polarity. Why does DNA replica tion
occur within such ' forks'? 56. Given below Is a heterogeneous RNA formed during
(b) Name two enzymes involved in the process of eukaryotic transcriptio n.
DNA replication, along wi th their properties.
(Al 2015J
LJl_ 3·
so Explain the process of DNA replication with the help s·
of a replicating fork_ (Delhi 2015C) A)
How many introns and exons respectivel y are formed
s.5 Transcr iption in this hnRNA?
(a) 7, 7 (b) 8, 7 (cl 8, 8 (d) 7, 8
IXt<•I ,;i
(Term 1, 2021-22J [A
51.. In a 'transcriptio n unit', the 't erminator' is located
towards the
57 In a bact erium, when RNA po lymerase binds
(a) 3 · end of the template strand to the promoter on a transcriptio n unit during
(b) 5 • end of the template strand transcriptio n, it
(cl 5' end of the coding strand (a) terminates the process
(d) 3· end of the coding strand. (b) helps remove introns
52.. Assertion (A) : Primary transcripts in eukaryotes are (c) initiates the process
subjected to splicing to remove the introns. (d) inactivates the exons. (2020J
Reason (R) : Primary transcripts contain both exons
and intrans and the introns are non-functio nal in M£11 (1mark)
eukaryotes. 58. What is a cistron? (A l 2015J
(a) Both Assertion (A) and Reason (R) are true and
Reason (R) is the correct explanation of the 59. Write the function of RNA polymerase II.
(Foreign 2015J
Assertion (A).
(bl Both Assertion (A) and Reason (R) are true, but 60. Name the enzyme that transcribes hnRNA in
Reason (R) is not the correct explanation of the eukaryotes. (Delhi 2015 C)
Assertion (A).
(cl Assertion (A) is true, but Reason (R) is false. 61. Differentia te between exons and introns.
(d) Assertion (A) is false, but Reason (R) is @ (1/ 3, Al 2015 CJ

true. (2~ 4J ]J WffilM (2 marks

~ ) __
53. A region of coding strand of DNA has the following
nucleotide sequence 5' -ATGCGGC - 3' 62. Given below is one of the strands of a DNA segment:
The sequence of bases on mRNA transcribed by this , TACGTACGTACGTACG ,
3 5
would be (a) Write its complemen tary strand.
(a) 5' - AUGCGGC - 3' (b) 3' - AUGCGGC - 3'
(bl Write a possible RNA strand that can be
(c) 5' - TACGCCG - 3' (d) 3' - TACGCCG - 5'
(Term I, 2021 · 22) 1]J
54 Which one of the following statement describe the
transcribed from the above DNA molecule
formed. (2020J[Ap-
function of the promoter in a transcriptio n unit? 63. Draw a schematic diagram of a transcriptio n unit
(a) Signals the termination of polypeptide chain. with the polarity of the DNA strands and label coding
(b) Serves a sequence where transcriptio n will strand, template strand and terminator. (2020 CJ
initiate.
(c) Serves as DNA template for transcriptio n to 64 Differentiat e between a template strand and coding
take place. strand of DNA. (2/ 3, Delhi 2015C)
, ◄
146 ~ C135F Chnmplon lllolor,y Un,~ 11
(,1)Hy brirl : Heavy, 1 : 16 WfflM 12 mnrl<s)
(b) light : Heavy, 1 : 3 t
40 Dlscu~s tho role, I he cn7yme DN/\ llg;isp pl;iy,, dur1n
(c) Hybrid : Het1vy, 1 : 31 8
DNA rer,lic;itlon. /Or lhl 20 J6)
(d) Light : Hc,w y, 1 : 05
3:; Given below is n list of steps M eselson .incl St.ihl •·•-:,•t•1..j■
• (3 m;irks)
carried out in their experiment to prove th.it DNA Describe the exper iment where M :itt.llcw Mr•~••l'o
• l n
replicat ion is scmi-co nscr.rntivc. Select the opl lo11
•

and Fr,1nklln Stahl used heavy Isotope or nllrow]n

that gives the correct sequence or steps foll ow en by
/2020/f ,,
them.
11
(i) Bacteria t r;insfcrre d to ;i N ' medium and •12 Explain the mechanism of DN/\ repllc,1tlon with th,,
sampled every 20 minutes. help of i'l repllcnll on fork. W hal role doc'.i l he cn7Yrn,,
11
(ii) All bacteria contain hybrid DNA (N • DNA and DNA llgase play In a DNA repllc;ition fork?
N ' ~DNA}. (Del/JI 2019)
(iii) Bacteria grown In N ' s medium for many
generations. ,13, Answer the followin g ques tions h.1sed on Mc5obon
15
(iv) All bacter ia contain N DNA. and Stahl's experim ent on E.coli:
(v) Bacteria contain either all N DNA or all hybrid
14 (a) Wri te the name of the chemica l suh-;tancc used
DNA. as the only source of nitrogen In the experiment
(a} (ii) ➔ (iv) ➔ (iii) ➔ (i) ➔ (v) (b) Why did they allow the synthesis of the light and
(b) (i) ➔ (ii) -> (v) ➔ (iv) ➔ (iii) the heavy DNA molecules In the org;inism?
(c) (iii) ➔ (iv) ➔ (i) ➔ (ii) ~ (v) (c) How did they distingu ish the heavy DNA
(d) (iv} ➔ (iii) ➔ (ii) ➔ (v) -► (i) (2023) l R"I molecule s from the light DNA molecule,;?
Explain.
36 Given below are the illustrati on of the differen t
steps of experim ents conducted by Macleod, Mc (d) Write the conclusion the scientist s arrived at, at
Carty and Avery to find the chemical nature of the the end of the experim ent. (Al 2019) t
'transfor ming principle' as DNA. Select the option 1
44. (a) Why does DNA replication occur within a
that incorrec tly depicts the step of the experiment.
replication fork and not In Its entire length

gA s Heatkilled
bact eria (b)
simultan eously ?
" DNA replicati on is continuous and
Bact erial t Filtrate discontin uous on the two strands within the
(2019)
r eplicatio n fork." Give reasons.
RNase 45. Describe the experim ent that hel ped demonstrate
p the semi-co nservati ve mode of DNA replication.
(De/hi 2016)
E~~~j
g;:;:} OR
~
I How was a heavy isotope of nitrogen used to provide
l
R bacteria R bacteria R bacteria R bacteria exper imental evidence to semi-con servative modeof
(live) (live) (live) (live) (Foreign 2015)
DNA-re plication ?
t t t t OR
No No
transform ation Transform ation transform ation Transform ation Describe Meselso n and Stahl's experim ent to prove
(c) (d)
(a) (b) that the DNA replica tion is semi-conservative. ~

pJ
(Term I, 2021-22) (A (315, Al 2015C) ~
37 Meselson and Stahl carried out centrifug ation in
CsCl 2 density gradient to separate :
MiilA 15 marks)
(a) DNA from RNA 46. (i) Draw a labelled diagram of a replication fOfk
(b) DNA from protein in a prokary ote indicatin g the process of DNA
(c) the normal DNA from 15 N-DNA replicati on.
(d) DNA from tRNA. (2020) (.R) ' between the two newly
(ii) Differen tiate
titll llmark) _ synthes ised DNA strands within the fork.
01
(iii) Name the enzymes involved in the process
38. Write the dual purpose served by deoxyrib o- DNA replicati on.
nucleoside triphosp hates in polymer isation. (2018) (iv) Name the eukaryo te where the senv-
3 9. Name the source of energy for the replicati on of conserv ative mode of replicntion w~
DNA. (1/ 3, Delhi 2015C) experim entally proved. (2023) U
r:
Bosi5. of Inherita nce
145
, 11 ,
{'-!_,i(:<Wv

(b) In the above experi ment, " heat w hich ki lled one
• • (Smarks)
type of bact er ia. did not dest roy t he proper t ies
_ (a) How are t~ fo~lowing formed and involved in o f genet ic materi al " Justify (20 19 CJ
17
DNA packaging in a nucleu s o f a cell?
(i) Histon e octam er 26. (a) State the ·centra l dogma' as proposed by Franci s
(ii) Nucleo some Crick. Are there any except ions to i t? Suppo rt
(iii) Chrom atin your ansv,e r w ith a reason and an examp le.
(b) Differe ntiate betwe en euchro matin and (b) Explain how the bioche mical charac t er isat ion
(Delhi 2016) (nature) of 'Transf orming Princip le' w as
hetero chrom at in.
determ ined. which w as not denne d from
Griffith's exper iments. (2018)
5.2 The Search for Gen etic
27 List the criteri a a molecu le that can act as geneti c
Mate rial materi al must fulfi ll. Which one of the criteri a are
best fulfille d by DNA or by RNA th us making one
of them a better geneti c materi al than t he other?
(Delhi 2016) u',._
18. Assert ion (A) : RNA is unstab le and can mutate at a Explai n.
faster rate. 28. Answe r the followi ng questi ons based on Hersh ey
Reason (R) : Th e p r ese nce of 2 ' - OH grou p i n and Chase experi ments :
every nucleo tide ot RNA makes it labile and easily (a) Name the kind of viru s they worke d with and
degradable. why?
(a) Both Assertion (A) and Reason (R) are true and (b) Why did they use two types of culture media to
Reason (R) is the correc t explanation of the grow vi ru ses in? Explain.
Assertion (A). (c) What w as the need for using a blende r and later
(b) Both Assertion (A) and Reason (R) are t rue. but a centr ifuge during their experi ments ?
Reason (R) is not the correct explana,t ion of the (d) State the conclu sion drawn by them after the
Assertion (A). experi ments. (Delhi 2016)
(c) Asserti on (A ) is true. but Reason (R) is fa lse.
(d) Assertion (A) is false. but Reason (R) is Q 29. (a) Descri be the series of experi ments of F. Griffi th.
(2024) @ Comm ent on the signific ance of t he results
true.
obtain ed.
UN £1 mar&_ _ _ _ _ (b) State the contrib ution of M acleod. McCa r ty
(Al 20 16)
and Avery.
19. Why is RNA more reactiv e in compa rison to DNA?
(Delhi 2015C) 30. How did Hershey and Chase established t hat DNA is
transfe rred from virus to bacter ia? (Delhi 2015)
Attil (3 marks) 31. (a) Descri be the experi ment w hich demonstr ated
20. Explain the discov ery made by Hershe y and Chase the existen ce of "trans formin g princip le".
using radioa ctive sulphu r and phosph orus in their (b) How was the bioche mical nat ure o f t his
experi ment (2020J (]J "transf orming princip le" determ ined by Avery.
M acl eod and M cCarty? (Foreign 2015)
21. Why is DNA a better genetic materi al when compa red
to RNA? (Delhi 2015C) JL 32. How did Alfred Hershe y and Marth a Chase
conclu sively est ablish that DNA is the geneti c
Mtl l (Smarks) materi al? Explain. (Foreign 20 15)
22 Stabili ty, as one of the proper ties of geneti c materi al. 33. How did Griffith prove transfo rming princip le in
was very eviden t in one of the very early experi ments genetics? Explain the proced ure. (Delhi 20 15C)
in geneti cs. Name the scient ist and @
descri be his exper im ent. State the • ~ 5.4 Repl icati on
conclusion he arrived at. (2024) lM.i
23. Explain Griffith's experi ment condu ct ed in search of
genetic materi al and write the conclu sion he arrived 34. In an experi ment. E. coli is grown in a mediu m
14
NH 4 CI (14 N is the light isotop e o f
at How did Avery, M acl eod and M cCarty @ contai ning
establish the bioche mical nature of the ~
JI nitroge n) followe d by growin g it for six genera tions
in a mediu m having heavy iso t ope of nitroge n ( 1 N).
5
"Genet ic Materi al" identif ied by Griffit h? (2024) ®!.I
After six genera tions. their DNA w as extrac ted and
24 - Describe the experi ment carried out by Her shey and
subjec ted to CsCI densit y gradie nt centri fugat ion.
Chase. Write the conclu sion they arrived al. (2020) Identif y the correc t densit y (Light /Hybrid/ Heavy )
25- (a) Explain Griffit h's 'transf orming princip le' and ra tio of the bands of DNA in CsCI densit y
experiment. gradie nt centrif ugatio n.
 mm (W, ~ ( lt.Hnplon l11r)ln~y ( 1,,.,., \)

[ ~•. ·· ~ v-i=f1i=l·ftt,t•1!t¥Jit·hhr~
5.1 Tlw DN/\ U N nnH' lhr· neg:il lv,•ly r h,lrf:<'cl :ind pc,c,it lvC'ly rh.,rP."d
ro1npnnc nt r. or iJ nu<1,,w,ornc'. (n c11i1?O JJC)
•~Ge•■ ......f...jra■• (2 morl<s)
1. fho lypr> u l 1\011<1 rc •p1W,l'nlc:d by 1111 • dullc•d llrn·
· In , 1 ~, he11w l Ii 11olv1111< l<'olld<• c:11.1111 I•, ? /\ltl\011r:h ,1 prol<;iryr, llc <.ell 11,,c; no clefinr,cl nut leus
/ S • II yc l l)N/\ I'> not <;c;il ter cd th roughout the ,ell FYplain
I'
'-.,. 5 ····· IJ /2018)
p/ 10. Oco;<.rlbe lhc c; I rue. l ure of , 1 nucleosome (De /hi 20 17)
; s ······
p'
IJ 1 ] . Wh;,t I•; ccn l r~,I clo1~ma? Who proposed 1t,

's ······ U
p/
(2/5. Al 20 I SC) R'
........... WtJI• (3 marks)
(il) hyclrol!Cll bond
12 (,1) lden tlly l he picture r_:iven below ;mcl name the
(bl
(cl
(d)
pcpl Ide bond
N· clycosltllc llnknge
phosphodle!iter bond.
e I
(202'1) I U
tool under w h ich it wa~ view ed
••• "'-1 . .. .. ... . .. , . , r, ·, 7,:/ • 4i l' " "'' t ' •• -.. - ,,, •· .,1 ·,/ • •
,., 4. I"' \,,_. ·"'
·:•,'.r·:a · r·· ,:.:,,- •'·.;,
!..... ....... lf 'l:· . .-, . .,,, ....-~-·:, • ~ ~ ·
·.-,,"'"'•r,~)-.· . .,~ :., ,~ '-·'l"r .. • ,,., J ..-.... ..":
\
1,11.,,l, '.•
'<-/ :/(-,;. ;11.:,1'.::'·"'i~~\i~• , ..\::',~~..? ~•t..r.-:•1
, ,._. .• ,l . ,,~ .. ('( " •'i ~.,,.\ 'l 'l'lll t--.,,J ~ j • ' ~••• ,,...- 'e
j
~..... r;,:~~" -~•--:,"=-.,.,;'Y~.,: :x>..,~-_; ';~ _::._.;~p~1r;;
V !f) ~
. , ..
2. In the double hellc;il structure or DNA molecule, lhe
slr.1nds ;ire ;-i•;));,.i;h :~t,..·:',·?,~~·!·.~~-<i'-{'.~:?;., t:i~~fl
(il) ldcntlc;:il ;ind complc mcnlary -./1 ,'r?, 'f'HA--~15
J, • h . ~. • , :.,•, ~
•,:;,(,•~•,<:, • •:i~ t:!,:-.,~ •r.,. •~,?').~~~
:rf1,.,~..r'~" · - ~J -'l r;i --..p,----:t; .vt~ . A

(bl ldentlc;il ;incl non-complementary /l~ r.-.,.f,~., ~ :.-,;,;: ,, ;:-~~::'J;.:.:,;:,;':{-,•1.'i:J.! . --;,,r:{:~.{e-1[· ,,;
........~. 1...~ -c~•;'..: \::.cltr,~1; ..~.,:; ... ,l ~~ ·':;-,.,.r; ....."?;1~;.Jml
(c) ilnll-parallel ;:incl complementary J! ~,~.,.. . _'-;-! ~r.'·t.•4 ' 17 ..(-;.'.?Xl'')tt',__~~-•-l!•t.~~ ; ;~_<~· ft., ,,1••,'(itJJ1
.,<,J, ,-~:--,: "f}"'"' I •, • TT . " "-L: • •~ •• • _, " ctr
1.;.:17, ,1;,"(_,~··.'.,10~i-1.,:-.?.~·~,•,:.'.":-~:,,~.\~:c-·~:...r~~~....:
(d) antl·par;:illel and non·complementary. (20 2 4) ( R J f\~ "t~..;'Q :,.#,~ol' - ~ turi. ~ • .,_-.._;(_)1i~"j~,....,,. .,. l - • ; ) : ~
3 A DNA fr.igmcnt h;is 3000 nucleotides, out of which ~~-i~•:~!-:;1.:\~~i~~{~~~f.:ti..~~:-':B .QJ~Yt.~1
1':°?'. !£<$;1-.~1:l-'{~\J:,.i~,':·6 ''_;1;_:.v-:f~•0~
1

160 ;ire guanine. How m,1ny bases having double I)' • -·~.~;\ff-~t·,, ;.;-. 'l,·%'1t i...,.':1:.·,• .,:....,. ,..,.,,_-:4
hydrogen bonds between them does this DNA
fragment possess?
~;}~~~ t~~~~tc1i,~(f.t.J;],f~\:~i~
,,x'.,~;-:.•-~.:.:: ~tr("'"'· r. !..~,,.. ,~,:,1....,,~u!~·.... ,.d~;l;'.;.~~
i
(a) l.60 (b) 320 ~ (bl What do the d ar k spo ts repr esent in @
(cl 1340 (d) 2680 (2024) lEvJ ' the picture? Ex pl ain how and w hy - ,...
are they formed. (2024) Ae,
4. What would be the effect on hlstone proteins in the
nucleus, on neutralisation of their positive charge? 13. The length of DNA in any cell is far greater than the
(a) They would bind the DNA tighter. dimension of its nucleus. Explain how this enormous
(b) They would separate from DNA. DNA is packaged in a eukaryotic cell. (2023) u"
(cl They would no longer attract each other.
14. (a) A DNA segment has a to tal o f 1000 nucleotides.
(d) They would cause supercoiling of DNA.
out of w hich 240 are adenine containing
(Term I, 2021 ·22J l u"J nucleotides. How many pyrimidine bases this
5. A DNA molecule is 160 base pairs long. It has 30% DNA segment possesses?
guanine. How many adenine bases are present in this (bl Draw a diagrammatic ske tch of a portion of DNA
DNA molecule? segment to support you r answer. (Delhi 2015)
(a) 48 (b) 64 (c) 96 (cl) 192 15. (a) A DNA segment has a total of 1.500 nucleotides.
(Term I, 2021·22) ~ out of which 410 are guanine containing
6. In prokaryotes like E.coli the DNA In the nucleoid nucleotides. How many py rimidine bases this
region Is organised as segment possesses?
(a) negatively charged DNA wrapped around hi stone (b) Draw a diagrammatic sket ch of a portion of DNA
(b) densely packed chromatin with NHC proteins segment to support your answer. (Delhi 2015)
(c) large loops held by the proteins 16. (a) A DNA segment has a total of 2,000 nucleotides.
(d) many repeating units of nucleosomes.
out of which 520 ar e adenine containing
(Term I, 2021·22) ( RJ nucleotides. How many puri ne bases this DNA
segment possesses?
M1• (1mark) (bl Draw a diagrammatic sketch of J portion or
7. Name the transcrlptlonally active region of DNA segment to support your ;inswer. ...
chromatin In a nucleus. (Delhi 2015) (Delhi 2015) E1