Statements below show three xe6 h l,;nbd7hdouble-stranded nucleotide sequences. Which of these sequence7; lhx hned,b6s of base 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 structurev,g,:vrymzc v9 17miz based on the tetranucleotide hypothesis proposed by Levene that DNA was made up of equal amounts of adenine, guanine, cytosine and thymine. This hypothesis was a problem of induction, because it was basevi:vm rgyz7z ,1, m9cvd 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 ribw(g b(oj r*ru: 1zq.iyosomes labelled in the micrograph?

  A strand of nucleotides reads CCUAGAGCUUACCG. Which type of pentose sugar could2 v ;oi2 en g(htgxet,75(u;tvb g9daq be o v2x 9h;tt,7eg(vqg(;5gi ben2uatdfound in the nucleotides in this strand?

  Which of the following processes is most directc*y iksy(zc s1:h2po. 41xwbd ly involved in the formation of n wk:hzyso1y4s1 cb( d.2ci*pxucleic acids such as DNA?

  What distinguishes uracil from th*p+8 ea)tyazwymine?

  Which statements are characteristie78pj.cl a o*8ko hh)jcs 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 nucleotide base sequ abc*-5 xpu8y0fm.mxxp 3y,uj ence and genome size (number of base paifamu 80puxmxyc-*x3p ., 5jybrs, bp) for different species.

Which conclusion can be drawn, based on the table?

  How does the genetic code p/ pquhdxa 9+j, c/yrh4rovide evidence of universal common ancestry?

  The diagram depicts /zcic m:r7id9nucleosomes.

Gel electrophoresis is a 2n+aztek so q-irg-dzx r8 t+)5w 5:uatechnique often used to analyse DNA molecules. It includes a gel and an electric field. The diagram below shows t285wr n-+s qt -a)ur+ox5e ga:z iktzdhe 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 an(gb esv;mbq )65xz 0j*kbp ;aad three mature mRNA transcripts where the introns have been removedbvqj g; s( *6mpb)abaxk0ze5 ;.



What is an advantage of the above process?

  Which of the following is gr)5 nkq r3:/deksmv :a similarity between transcription and translation?

  The diagram shows the structure of a DNA fragment. Which bonds easily9+wgmoq4-w qd6cy ro - break and 9c4good-q- wqyw6+m rreform?

  What would make one DN:o f2nq b2r (;qc)hbilA molecule more stable 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 conducteiq6bn+vb8 us8d bsz t( 4r8mecv6,l*od an experiment to investigate whether DNA or protein serves as the genetic material. They cultured 2 batches of viruses, one in a medium containing radioac,* ib+sl4ot8v uv8q 6 bn dsrzbme(86ctive $^{35}S$ 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 correctly matched in the table olu/ nf-f),hqs hr++u7gm s:f below?

  Which statement highlights the importance of nuclt;rje mdo b8,9* v s)+mdtd0yheosomes in DNA supercoiling ?

  The image shows many ribosomes on a mRNA mol4bm 3ri/fi0vkv i5iz( ecule. How many unique polypeptide chains are bez/ii05mk 3(b4i rfviving translated?

  Which of the labelled structures shows the correct dn4cbjhzxwq-2-f lj,y;t d78 uirectionality of the DNA molecuuwq8bj znj h;-xf-d,2cty7 l4 le?

The diagram below shows the structure of DNA nqxz+ k*fld nl-*dr6+hucleotides.

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 cusf85mmd9rv13c z37l1 cynz* , uon nlwltured viruses that were radioacti,7nr lds*3nn y11v9zz3cl f8ow5mu mc vely labelled 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, uko7, o j9 oqhzjz-8;irvft p+9+fv3kand R if S is a pyrimidine?

  How did radioisotopes help make the investi*h7 l+meg;wtl gations by Hershey and Chase possible?e7 tlwh;+mg *l

  What feature of the DNA molecule qgn,6 z:s8pa ackg; k8;ss3nb was utilised by Hershey and Chase in order to identify that viral DNA is able to enter host cells, bqzk,kss86g ca3anng :8pbs ;;ut most of their protein is not?

.

The image below shows a u r7gzj;6hagfhh t.ursw -2o*,-ts t +short fragment of the DNA molecule.



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 showxf9a-y; anxs0s the correct components of one nucleosome?

  Hershey and Chase conducted experiments using the radioavha)sokzwv8v/d 1 8fi8l 9 zd3ctive 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 experia0xq4ipx . oraps,v/wy8d . 4bment conducted by a team of researchers investia,d 4 .i.xav /qbyrxwpso 804pgating the relationship between the composition and melting point 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 that are essential to all living orgar.k g6qwgs/xv0p;j c/nisms.
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 fragment of the mkw/a4-az+ybk5z c f2a j7vy8DNA 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.