EPFO APFC 2023 General Studies · Question 118 of 120

Correct — B, (b) click chemistry and bioorthogonal chemistry. The Nobel Prize in Chemistry for 2022 was awarded jointly to Carolyn R. Bertozzi, Morten Meldal and K. Barry Sharpless for the development of click chemistry and bioorthogonal chemistry, and the citation uses both phrases because the prize recognises two connected achievements rather than one. Click chemistry is the idea that useful molecules can be built by snapping together simple building blocks with reactions that are fast, reliable, high-yielding and free of unwanted by-products, instead of by the long and wasteful syntheses that organic chemistry had traditionally required. Sharpless set out the concept and gave it its name around the turn of the century, and the reaction that became its centrepiece — a copper-catalysed joining of an azide to an alkyne — was arrived at independently by Meldal and by Sharpless. It works in water, tolerates a wide range of other chemical groups and gives a single product in high yield, which is what makes it a tool rather than a curiosity. Bertozzi's contribution was to make such reactions usable inside living systems. A reaction performed in a living cell must not interfere with the cell's own chemistry, and the copper catalyst that made the original click reaction work is toxic to cells. Bertozzi devised copper-free versions, using a strained ring to supply the driving force instead, and coined the term bioorthogonal for reactions that proceed alongside the biochemistry of a living organism without disturbing it. She used them to attach fluorescent markers to the sugars on the surfaces of cells and so to map glycans in living organisms, which had not previously been possible. The practical reach of the two ideas is what the prize citation emphasises: pharmaceutical development, the mapping of DNA, the creation of materials fitted to a purpose, and the targeting of cancer drugs to tumours. One point of Nobel history is worth attaching to this prize because it is examinable in its own right: Sharpless had already received the Nobel Prize in Chemistry in 2001, for work on chirally catalysed oxidation reactions, and the 2022 award made him one of the very small number of people to have won two Nobel Prizes.

• (a)CRISPR/Cas9 genetic scissors — The genetic scissors were the subject of the Nobel Prize in Chemistry for 2020, not 2022. That prize went to Emmanuelle Charpentier and Jennifer A. Doudna for the development of a method for genome editing — the CRISPR-Cas9 system, which allows the DNA of animals, plants and micro-organisms to be cut at a chosen position with very high precision. It was a notable award for two further reasons that examiners like: it was the first science Nobel awarded to two women jointly, and it came only eight years after the underlying paper, which is unusually fast for a Nobel Prize. The option is placed here because CRISPR is the piece of recent chemistry that a general reader is most likely to have heard of, so a candidate who remembers a famous chemistry prize without its year will reach for it. Keeping the last several years of chemistry prizes in order, with a phrase for each, is the only protection against this kind of option.
• (c)lithium-ion batteries — Lithium-ion batteries were the subject of the Nobel Prize in Chemistry for 2019, awarded jointly to John B. Goodenough, M. Stanley Whittingham and Akira Yoshino for their development. The prize recognised a technology rather than a discovery in the usual sense: a lightweight, rechargeable and powerful battery that made portable electronics practical and is now central to electric vehicles and to the storage of energy from renewable sources. Goodenough was ninety-seven at the time and became the oldest person ever to receive a Nobel Prize, which is the detail most often examined about that award. As with the genome-editing option, the difficulty here is that the subject matter is famous and the year is not, so a candidate answering from general awareness rather than from a memorised list has three plausible chemistry prizes in front of them and no way to choose between them.
• (d)palaeogenomics — Palaeogenomics was indeed the subject of a Nobel Prize for 2022 — but of the Nobel Prize in Physiology or Medicine, not in Chemistry. That award went to Svante Pääbo for his discoveries concerning the genomes of extinct hominins and human evolution: he sequenced the Neanderthal genome, discovered the previously unknown hominin Denisova from a finger bone, and showed that gene transfer occurred from these now-extinct hominins to Homo sapiens after the migration out of Africa. This is the most carefully placed option in the set, because it is right about the year and wrong only about the discipline, and a candidate who has revised the 2022 prizes as a block and remembers palaeogenomics among them can land here without noticing that the stem specifies chemistry. When revising Nobel Prizes, the year and the prize must always be memorised as a pair; either alone is worth nothing on an item constructed like this one.

The Nobel Prizes were established by the will of Alfred Nobel and first awarded in 1901 in physics, chemistry, physiology or medicine, literature and peace; the prize in economic sciences was established later by Sveriges Riksbank in Nobel's memory. The prizes in physics and chemistry are awarded by the Royal Swedish Academy of Sciences, that in physiology or medicine by the Nobel Assembly at the Karolinska Institute, that in literature by the Swedish Academy and that in peace by a committee appointed by the Norwegian Parliament. Laureates are announced in October and the prizes presented on 10 December, the anniversary of Nobel's death, in Stockholm — the peace prize in Oslo. A prize may be shared by up to three people and is not awarded posthumously. The chemistry of this particular award belongs to the field of synthesis. Click chemistry is a design philosophy rather than a single reaction: build complex molecules by joining small, ready-made units with reactions that go to completion quickly, work under mild conditions, generate no troublesome by-products and are insensitive to water and oxygen. The copper-catalysed azide-alkyne cycloaddition is the standard example. Bioorthogonal chemistry is the subset of such reactions that can be carried out inside a living organism, because they neither interfere with nor are interfered with by the organism's own biochemistry; the copper-free, strain-promoted version of the azide-alkyne reaction is the best-known. Together they underpin antibody-drug conjugates that carry a cytotoxic agent to a tumour, the labelling and tracking of biomolecules in living cells, and a great deal of modern materials and medicinal chemistry.

The last three items of this paper are current affairs, and the Nobel Prizes are among the most predictable of all current-affairs topics: they are announced on a fixed calendar, in six fixed categories, and every serious examination in the year following an announcement will test at least one of them. What makes the questions non-trivial is that the examiner does not ask who won — that would reward name-memory alone — but pairs a year with a category and offers four genuine Nobel subjects as options. This item does exactly that. Every one of the four options names something that really did win a Nobel Prize; three of them won it in a different year, in a different category, or both. A candidate who has revised laureates as a flat list of famous discoveries has no way through an option set of that construction, while one who has kept a small table of year, category and one-phrase citation answers it in seconds. The discipline the paper is rewarding is therefore structured note-keeping rather than reading volume. The stem is printed as an incomplete sentence completed by the options and ends without a question mark, which is this booklet's habit on several items in the closing stretch, and it should be read straight through into each option in turn.

• The Nobel Prize in Chemistry for 2022 was awarded jointly to Carolyn R. Bertozzi, Morten Meldal and K. Barry Sharpless for the development of click chemistry and bioorthogonal chemistry. The citation names both fields because the prize recognises two connected achievements: a way of building molecules reliably, and a way of doing so inside a living organism.
• Click chemistry joins simple building blocks with reactions that are fast, high-yielding, tolerant of water and free of troublesome by-products. Its centrepiece is the copper-catalysed joining of an azide to an alkyne, arrived at independently by Meldal and by Sharpless, who also gave the field its name around the turn of the century.
• Bioorthogonal chemistry consists of reactions that proceed inside a living organism without disturbing its own biochemistry. Bertozzi developed copper-free versions of the azide-alkyne reaction, driven by ring strain rather than by a toxic catalyst, and used them to map glycans on the surfaces of living cells — work now applied to targeting cancer drugs to tumours.
• K. Barry Sharpless had already won the Nobel Prize in Chemistry in 2001, for work on chirally catalysed oxidation reactions, so the 2022 award made him one of the very few people to have received two Nobel Prizes. The other three options in this item name prizes of other years or of another category.
• The three distractors are all real Nobel subjects: CRISPR-Cas9 genome editing won the chemistry prize in 2020 for Emmanuelle Charpentier and Jennifer A. Doudna; lithium-ion batteries won it in 2019 for John B. Goodenough, M. Stanley Whittingham and Akira Yoshino; and palaeogenomics won the 2022 prize in physiology or medicine for Svante Pääbo — the same year as this question, but a different prize.

• Revising laureates without their years. All four options here name genuine Nobel subjects, so an option set of this construction cannot be narrowed by recognising the science; the year and the category have to be attached to each.
• Missing that one option is the right year but the wrong prize. Palaeogenomics won the 2022 prize in physiology or medicine, and a candidate who revised the 2022 awards as a block without separating the categories will find it entirely plausible.
• Reaching for the most famous option. Genome editing is the recent chemistry prize a general reader is likeliest to have heard of, which is precisely why it is offered here; fame is no guide to the year.
• Assuming a Nobel Prize cannot be won twice by the same person. Sharpless received the chemistry prize in both 2001 and 2022, and that fact is itself examinable, so a candidate who rejects the option on that ground rejects the correct one.

Nobel Prize questions appear in the current-affairs section of practically every general studies paper set in the year after an announcement, and they take three forms. The first, used here, names the year and the category and asks what the prize was awarded for, offering other genuine Nobel subjects as distractors. The second names the laureate and asks for the field, or names the field and asks for the laureate. The third asks a structural question about the prizes themselves — which body awards which prize, how many people may share one, whether it may be awarded posthumously, or which prize is presented in Oslo rather than Stockholm. All three are answerable from a single page of notes that pairs each year with each category and a short citation, refreshed each October. Because the distractors are always real prizes from neighbouring years, partial knowledge is worth very little here and complete knowledge of a small table is worth a great deal.

No directly related past PYQ was found.

• practice — not a real PYQ

  The Nobel Prize in Physiology or Medicine for the year 2022 was awarded to Svante Pääbo for his discoveries concerning which one of the following?

  • (a)The genomes of extinct hominins and human evolution
  • (b)The discovery of the hepatitis C virus
  • (c)Receptors for temperature and touch
  • (d)Nucleoside base modifications enabling effective mRNA vaccines

  Answer(a) The genomes of extinct hominins and human evolution — Pääbo sequenced the Neanderthal genome, identified the previously unknown hominin Denisova from a finger bone, and showed that gene transfer took place from these extinct hominins to Homo sapiens. The hepatitis C virus was the subject of the 2020 medicine prize, receptors for temperature and touch of the 2021 prize, and mRNA vaccine technology of the 2023 prize.

• practice — not a real PYQ

  K. Barry Sharpless, one of the three laureates of the Nobel Prize in Chemistry for 2022, had earlier been awarded the same prize in 2001 for his work on which one of the following?

  • (a)Chirally catalysed oxidation reactions
  • (b)The development of the polymerase chain reaction
  • (c)The discovery of fullerenes
  • (d)Studies of the structure and function of the ribosome

  Answer(a) Chirally catalysed oxidation reactions — Sharpless shared the 2001 chemistry prize for that work, which is why his 2022 award placed him among the very few people to have received two Nobel Prizes. The polymerase chain reaction was recognised in 1993, fullerenes in 1996 and ribosome structure in 2009, all of them chemistry prizes of other years.