AQA GCSE Chemistry
AQA GCSE Chemistry 4.7.3 Synthetic and Naturally Occurring Polymers Exam Questions
Free AQA GCSE Chemistry exam questions for 4.7.3 Synthetic and Naturally Occurring Polymers, with a mark scheme for every pack. Covers addition polymerisation, condensation polymerisation, amino acids and proteins, DNA and other naturally occurring polymers.
4.7.3 Synthetic and Naturally Occurring Polymers exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About AQA GCSE Chemistry 4.7.3 Synthetic and Naturally Occurring Polymers
AQA GCSE Chemistry 4.7.3 is separate Chemistry only content about the large molecules that make plastics and living things. You learn how alkenes join by addition polymerisation and how to draw repeating units, then (Higher tier only) how condensation polymers form from monomers with two functional groups, losing a small molecule such as water. You also study amino acids, proteins, DNA, starch and cellulose. The topic is assessed on Paper 2 and builds on alkenes and functional groups from 4.7.2. Drawing repeating units and comparing addition with condensation polymerisation are frequent exam questions.
What you need to know
- Addition polymerisation Many small alkene monomers join to form a long polymer chain, with the C=C double bond opening. The repeating unit has the same atoms as the monomer, for example ethene → poly(ethene).
- Drawing repeating units Draw the monomer's carbon chain with single bonds, add brackets, extension bonds through the brackets and n. You should be able to go from monomer to repeating unit and back.
- Condensation polymerisation (Higher tier only) Monomers with two functional groups react, joining together and losing a small molecule, usually water. The simplest example uses a diol and a dicarboxylic acid to make a polyester.
- Amino acids (Higher tier only) Amino acids have an amino group (-NH2) and a carboxylic acid group (-COOH). They polymerise by condensation to form polypeptides and proteins; glycine is a simple example.
- DNA and natural polymers DNA is a large molecule made of two polymer chains of four different monomers called nucleotides, in a double helix; it encodes genetic instructions. Other natural polymers include proteins, starch and cellulose (from sugars).
Common mistakes in 4.7.3 Synthetic and Naturally Occurring Polymers
- Leaving the double bond in the repeating unit of an addition polymer. The C=C becomes a single bond in the polymer.
- Forgetting extension bonds or the n in a repeating unit.
- Saying addition polymerisation produces water. Only condensation polymerisation produces a small molecule as well as the polymer.
- Thinking a condensation polymer needs only one functional group per monomer. Each monomer needs two (or the two different groups on one monomer, as in amino acids).
- Confusing nucleotides (monomers of DNA) with amino acids (monomers of proteins).
Try three 4.7.3 Synthetic and Naturally Occurring Polymers exam-style questions
1. Draw the repeating unit of poly(propene) from propene, CH2=CHCH3, described in words. (2 marks)
Show the mark scheme answer
Two carbons joined by a single bond in brackets with extension bonds; one carbon has two H, the other has one H and a CH3 group; n after the bracket.
2. State two differences between addition and condensation polymerisation. (2 marks) Higher tier only
Show the mark scheme answer
Addition uses monomers with a C=C double bond, condensation uses monomers with two functional groups; addition gives only the polymer, condensation also gives a small molecule such as water; addition can use one type of monomer, condensation usually uses two different monomers (or one with two different groups).
3. Name the monomers that make up DNA and describe its structure. (3 marks)
Show the mark scheme answer
Nucleotides; four different types; two polymer chains forming a double helix.
4.7.3 Synthetic and Naturally Occurring Polymers FAQs
What does AQA GCSE Chemistry 4.7.3 cover?
It covers addition polymerisation and repeating units, condensation polymerisation and amino acids (Higher tier only), and naturally occurring polymers such as DNA, proteins, starch and cellulose.
Who studies 4.7.3?
It is separate Chemistry only content assessed on AQA GCSE Chemistry Paper 2, with condensation polymerisation and amino acids at Higher tier only.
How do I draw a polymer repeating unit quickly?
Copy the two carbons from the C=C, change the double bond to a single bond, keep all side groups where they were, then add brackets, extension bonds and n. Check the atoms match the monomer.
