Statements below show t4 8*:s iyuysqlhree double-stranded nucleotide sequences. Which of these sequences of base pairs is possq* yiu 4l:yss8ible 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 structure baseo+lxl 1wt 6y.dd 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 based on a limited set of data. Subsequent evidence and data revealed a more complex and accurate understanding of the struct6.1lxw +yt dolure, leading to the falsification of the initial hypothesis.

  What is the main role of the ribosomes labelle:l aqh3w61r5t c5pke qd in the micrograph?

  A strand of nucleotides reads CCUAGAGCUUACCG. Which ep 8:m/4p6 g-y nhozhzr6 d0kcd :e5matype of pentose sugar could be found 8p5md eh4h:6 d6nmk zpze-o yr/g:0acin the nucleotides in this strand?

  Which of the following processes is most directhzf(q( y* yh2jnh9 3nsly involved in the formation of nucleifnn*2 (yjs3qh9y h zh(c acids such as DNA?

  What distinguishes uracil from thz4dw bo ,vn2k;i (6. ekqfd*siymine?

  Which statements are characteristics of a DNA.* bt6amrin6d26ou(* iy0dpe2s r ue obz/*wx 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 nudvwiu e ug4,4 g2an n*:qww2-jcleotide base sequence and genome size (number of base pairs, bp) for different w*,v4g-:gj4ew 2nnudawiq 2 u species.

Which conclusion can be drawn, based on the table?

  How does the genetic code provide evidence of universal cof*hbz- 7fq1(lxgx ht2mmon ancestry?

  The diagram depicts nucleosomesa svj4u5t( z4ot , c4/kbfb6sf.

Gel electrophoresis is a technique oflpl/7 fl0tcw -zzr4i, ten used to analyse DNA molecules. It includes a gel and an electric field. The diagram below shows the outco r7 lzf w/l0tz4-plci,me 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 mature mRNA transcripts 4n9 *q)nexv: j/gld cxwhere the introns have been removend/lx4:g *) qnc9vxejd.



What is an advantage of the above process?

  Which of the following is a similarity between transcription and translatio ,/wefpy*ao8d *qp63v kog*e mrkd:/ gn?

  The diagram shows the structur z8l1.ul*godve of a DNA fragment. Which bonds easily break and rlod u .lgz*8v1eform?

  What would make one DNA molecule more stable tha qf0z 8/ehz3)c (iofwln 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 (fg p17j/ku gpexperiment to investigate whether DNA or protein serves as the genetic gppu g1j7/fk( material. They cultured 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 correctly matched in t69zfl8xv9gys c8 ssngr8kame8 w u (+:he table below?

  Which statement highlights the importance of nucleosomes s 9nckz8hf53x h)4ep mr/olf9 in DNA supercoiling ?

  The image shows many ribosomes on a mRNA moltvb- qv:wv)7eecule. How many unique polypeptide chains v7tq :-vbew) vare being translated?

  Which of the labelled structures shows y 1huu7t ,5fj; fmtc:ythe correct directionality of the DNA mol:uyftm ,uf;1ht5 jyc 7ecule?

The diagram below shows the structure of a+*b.qocs3h7 cezyy3 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 virusesybsx/r gm0t ewp/i 65rv(r 2jo23shr1 that were radioactively labelled witrjxs51 t/y g2w 6m(vs/2rbo3rpr ih0eh 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, (j2)v;/e qfao pon;iband R if S is a pyrimidine?

  How did radioisotopes help make the investigations by Hershey 8syx3k -+iq9 :r7aebde.f qi+sboiw, and Chase possible?sqxesfaiw .: + 3qor,iebb79yd -i+ 8k

  What feature of the DNA molecule was utilised by Herdksq: z*g.ert k2+8 bsshey and Chase in order to identifs8+z *k t: r.e2gqdbksy that viral DNA is able to enter host cells, but most of their protein is not?

.

The image below shows a 90, (uxzb:;co9gdcbh3fjk+ 9hexlw q umr,/ vshort 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 shows the correct9xi,860q z)kdtkb ccg components of one nucleosome?

  Hershey and Chase condu6 +)xunll( vc0tiqw, ) wiba,lcted experiments 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 tk xoyp- x80,vphe results of an experiment conducted by a team of researchers investigating the relationship between the composition and melting point of different DNA samples. At the melting point, the DNA double helix separates intoyx0 po 8kxvp,- 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 aclq2 m e3x/u0cla)n -qzids that 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 fragment of the r)z htcyu ;86/y 9p 3bnrilf6w1fl8s0yfc+koDNA 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.