Statements below show three double-stranded nucleotide s;cjjjoh 5h6 )bequences. Which of these sequences of bahj65) ;j cjhbose pairs is possible in a DNA molecule?

I. 5’- GGA CAG AGC -3’
3’- CCT GTC TCG -5’


II. 5’- GGA CAG AGC -3’
3’- TTC ACT CTA -5’


III. 5’- AGG GAC CGA -3’
3’- TCC CTG GCT -5’

  The diagram below shows the (oc xhcax v3fs1/4uy8structure based on the tetranucleotide hypothesis proposed by Levene that DNA was made up of equal amountsc1ca s48h uo3v(/fxyx of adenine, guanine, cytosine and thymine. This hypothesis was a problem of induction, because it was based on a limited set of data. Subsequent evidence and data revealed a more complex and accurate understanding of the structure, leading to the falsification of the initial hypothesis.

  What is the main role of the ribosomes labelled i za n 5v:jzrcybp6-u12n the micrograph?

  A strand of nucleotides reads CCUAGAGCUUz-rn 2 h6agq/tACCG. Which type of pentose sugar could be found in the nucleotides in t 6t-gz2aqhrn/ his strand?

  Which of the following processes32( egvce6c1te vnr(j is most directly involved in the formation of nucleic acids suc2ene6 gvrt 1 ecc(j3(vh as DNA?

  What distinguishes urac5wowbw sj0r er 7j,yv b1i,z,2il from thymine?

  Which statements are 6fw+zo/a/c sx characteristics of a DNA molecule?
I. The two strands are identical.
II. The two strands are antiparallel to one another.
III. The sugar-phosphate backbone is held together by covalent bonds.

  The table shows the nucleoo y *+4fb8wvciidvoanq lp :fr7z 1341tide base sequence and genome size (number of base pairs, bp) for dif8poz11b7*+i4 lf3ynvirwv 4qc:a fdoferent species.

Which conclusion can be drawn, based on the table?

  How does the genetic code provide eviden,bkah;* n awar)yg lixj*6k 9,ce of universal common ancestry?

  The diagram depicts ;i6+cw.) b. ck7gxzx sm;w zsanucleosomes.

Gel electrophoresis is a technique often used to analys:ue- ui3la)*wpp28qq g l9 ivqe DNA molecules. It includes a98* ulu 32-eqiagl viwqp:q)p gel and an electric field. The diagram below shows the outcome of gel electrophoresis.


1.DNA is a type of nucleic acid. State one location where DNA is found in cells.

2.Deduce, with a reason, which direction the DNA fragment moves through the gel.

3.Distinguish between the functions of DNA and RNA in unicellular organisms.

  The diagram below shows pre-mRNA and three matxsfw v81d;re4gal2ba uf2 b+9nq :ra+ure mRNA transcripts where the introns have been rxva b+fr8 2+sflae:bq4u;a1wd2nr g 9 emoved.



What is an advantage of the above process?

  Which of the following is 1 fnco,w6j7af6 b .exza similarity between transcription and translation?

  The diagram shows the structure of a DNA fragment. Which bonds qlc;f7+ nzz h:easily break and rez+7h:nqfcl;z form?

  What would make one DNA molecule more staqknax,7n t;sdtoytt 2d/o1uy3k,:kkk8k11n ble than another DNA molecule?
I. More G-C base pairs than A-T base pairs
II. More hydrogen bonds between base pairs
III. Greater distance between A-T base pairs than G-C base pairs

  Hershey and Chase conducted an experiment to investigate whethllw4(v i/qvm w vblu 9c826/o9s/iaqy er DNA or protein serves as the genetic material. They culaib 8m6 9vcuiql92s l/4w wvy( o//vlqtured 2 batches of viruses, one in a medium containing radioactive $^{35}S$ and one in radioactive $^{32}P$. They then introduced each batch of viruses to separate cultures of bacteria. After allowing time for the viruses to infect the bacteria, the culture solutions were centrifuged to separate the viral remains from the bacterial cells, forming two layers, the pellet and the supernatant.


Which component of the tube would provide evidence that DNA is the genetic material?

  Which function and process are corz2z c5jf1z;bf ds +-b zk+*bvhrectly matched in the table below?

  Which statement highlights the importance of nucleosomes in DNA supercoili;-vv5 3:tgubwpkx( jrng ?

  The image shows many ribosomes on a mRNA molecule. How many unique poma)we *ry/+g 2noeb+d lypeptide chains are ) an *o2m+ederg/y +bwbeing translated?

  Which of the labelled structures shows the correct directionality of the +. nt sv:/q-bmhra5zs/wq;nr DNA molecule? a /nrw-b qs/tr.n; z:sh+5mvq

The diagram below shows the s8q 9j3w;upyd etructure of DNA nucleotides.

1.State the component of DNA that is attached at position X.

2.Identify the type of bonding shown as dotted lines in the diagram.

3.The 5’ and 3’ linkages in DNA play an important role in replication, transcription and translation.

3.1.On the diagram, label the 5’ prime and 3’ prime ends on both strands to show the direction of the DNA.

3.2.Outline how the processes of transcription and translation occur with regards to the formation of 5’ and 3’ linkages.

4.Explain how the DNA helix maintains its stability.

5.Erwin Chargaff’s data on the relative amounts of purine and pyrimidine bases played an important role in determining the structure of DNA.

5.1.Outline how Chargaff’s data contributed to our understanding of the structure of DNA.

5.2.State a proposed model of DNA that was falsified by Chargaff's data.

The Hershey-Chase experiment in 1952 involved cultured viruchu;4kd.m99ng z,rli g*zyj1ses that were radioactively labelygc9i g1z jmudr.n ,kz*l h94;led with either sulfur ($^{35}$S) or phosphorus ($^{32}P) in two separate flasks. Each batch of viruses was then added to separate cultures of bacteria. After allowing time for the viruses to infect the bacteria, the culture solutions were centrifuged to separate the viral remains from the bacterial cells, forming two layers, the pellet and the supernatant.


1.State reasons for using radioactive sulfur ($^{35}$S) and phosphorus ($^{32}$P).

2.Suggest one technological development, other than radioisotopes, that helped open up possibilities in understanding the overall structure of DNA.

3.1.Outline the results of the experiment that provided evidence to support the conclusion that DNA is the genetic material.

3.2.Describe how the 4 nitrogenous bases of DNA enables polypeptides to be coded for.

4.Explain how DNA can be packaged into compact units to form chromatin.

  What bases are P, Q, and R if S is a p54e, xibkpj599nohhvg y/ ;0xcp81 hxzbql5byrimidine?

  How did radioisotopes help make the investigations by Hershey 27 af +q6c;h vf6cqn*7komfle and Chase possible7f6;kmna+ol6c*ch7fv 2 q eqf?

  What feature of the DNA molecule was utilised by H.8q navz1*jyte27s vncc 9w7m gbl9+sershey and Chase in order to identify tha+ygvv.nsc 7ew1 j92n czb qla9m*7ts8t viral DNA is able to enter host cells, but most of their protein is not?

.

The image below shows a short fragment of the DNA mol 1-g tob f+.zzdc:pa8iecule.



1.Suggest one possible outcome if DNA consisted of two parallel strands instead of two antiparallel strands.

2.The structure of DNA is described as being a 'double helix'. Explain how this structure is related to the DNA function.

3.Compare and contrast the nitrogenous bases thymine and uracil.

  Which of the following shows the correct components *buu/k bk6 7ic,khhq4of one nucleosome?

  Hershey and Chase conducted experi)z rts.lrt+.g ments using the radioactive isotopes $^{35}$S and $^{32}$P which demonstrated that DNA is the genetic material. What would they have observed about the distribution of isotopes in the centrifuged sample if protein, rather than DNA, were the genetic material?

  The graph below shows the results of an experiment conducted by a team of resea3prirf5/d bl +rchers investigating the relationship between the composition and melting poi+r5lf/dr i3pb nt of different DNA samples. At the melting point, the DNA double helix separates into two individual strands.

Two DNA samples were compared, one consisting of only PQ pairs and another one consisting of only RS pairs. Letters P, Q, R and S represent different nitrogenous bases found in the DNA.


Based on the results presented in the graph, and your knowledge of nucleotide base pairing (between purines and pyrimidines), deduce which nitrogenous bases correspond to the letters P, Q, R and S.

DNA and RNA are nucleic acids thaeceopcoh y 52(4rx1 ,dt are essential to all living organisms.
1.Draw and label a diagram of a nucleotide.

2.Explain how the variation in base sequences leads to the ability of DNA to have an enormous capacity for storing genetic information.

3.DNA is a polymer of nucleotides. Describe the structure of DNA.

The image below shows a short fragmc:5( hwm1 s2v-e qoovbent of the DNA molecule.


1.Suggest one possible problem that could arise if DNA consisted of two parallel strands instead of two antiparallel strands.

2.State one place where DNA is found in cells.

3.Compare and contrast the structure of DNA and RNA.