| Date | November 2016 | Marks available | 1 | Reference code | 16N.3.hl.TZ0.15 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | State | Question number | 15 | Adapted from | N/A |
Question
The structure of DNA (deoxyribonucleic acid) has been studied in many different ways.
State the name of the component of DNA responsible for the migration of its fragments to the positive electrode in gel electrophoresis.
In 2010, scientists claimed that they had discovered a species of bacteria capable of incorporating arsenic in place of phosphorus into the bacterial DNA. This claim has since proved controversial. Suggest one technique or evidence that might help support the claim.
Markscheme
phosphato/phosphate «group»
Do not accept “phosphoric acid”, “phosphorus” or any formula.
mass spectrometry / X ray diffraction/crystallography / nuclear magnetic resonance «spectroscopy»
OR
bacteria able to grow in absence of phosphorus
OR
reproducible data
Accept abbreviations (eg, MS, NMR).
Accept “elemental analysis” or “atomic absorption spectroscopy/AA(S)”.
Examiners report
Syllabus sections
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17N.3.hl.TZ0.13:
The stability of DNA is due to interactions of its hydrophilic and hydrophobic components.
Outline the interactions of the phosphate groups in DNA with water and with surrounding proteins (histones).
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17M.3.hl.TZ2.15a:
Outline how its structure allows it to be negatively charged in the body.
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17M.3.hl.TZ1.15d:
The sequence of nitrogenous bases in DNA determines hereditary characteristics.
Calculate the mole percentages of cytosine, guanine and thymine in a double helical DNA structure if it contains 17% adenine by mole.
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18M.3.hl.TZ1.6d:
Describe how DNA determines the primary structure of a protein such as insulin.
- 18N.3.hl.TZ0.7b: Suggest one concern about the use of genetically modified, GM, food.
- 18N.3.hl.TZ0.7a: State the feature of DNA that determines the primary structure of proteins synthesised by a...
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16N.3.hl.TZ0.15b:
In 2010, scientists claimed that they had discovered a species of bacteria capable of incorporating arsenic in place of phosphorus into the bacterial DNA. This claim has since proved controversial. Suggest one technique or evidence that might help support the claim.
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17M.3.hl.TZ2.15b:
Deduce the nucleotide sequence of a complementary strand of a fragment of DNA with the nucleotide sequence –GACGGATCA–.
- 19N.3.hl.TZ0.13b: Explain how the double-helical structure of DNA is stabilized once formed.
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18M.3.hl.TZ2.12:
DNA is a biopolymer made up of nucleotides. List two components of a nucleotide.
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19M.3.hl.TZ1.14a:
Outline what is meant by genetically modified organisms.
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19M.3.hl.TZ2.10b:
Describe what is meant by the genetic code and how it relates to protein synthesis.
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19N.3.hl.TZ0.13a:
List two components of nucleotides.
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20N.3.hl.TZ0.8b(ii):
The diverse functions of biological molecules depend on their structure and shape.
Draw the nitrogenous base that is paired with guanine in DNA, showing the hydrogen bonds between the bases. Use section 34 of the data booklet.
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19M.3.hl.TZ1.14b:
Outline one benefit of the use of these products.
