Carbohydrates, proteins and nucleic acids are types of biological molecule. Within each type, there are examples of molecules that can be described as polymers. (a) A polymer is a large molecule composed of smaller repeating molecules known as monomers. Complete Table 4.1 to produce a summary of some named biological polymers. Table 4.1 polymer constituent monomer type of bond between monomers

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2019). The mark or mark type is shown in brackets.

1. [4] (a) polymer constituent monomer type of bond between monomers amylose glucose glycosidic glycosidic ; A glucosidic cellulose glucose I details of bond collagen amino acid; peptide R protein (amino acid) DNA DNA nucleotide phosphodiester ; glycogen (α-)glucose ; glycosidic R B-glucose
2. [2] (b) two from 1 amylose composed of α-glucose (monomers) and cellulose composed of β-glucose (monomers); 2 (amylose) α-1,4 v. (cellulose) β-1,4 (glycosidic) bonds; R if amylose stated to have α-1,6 bonds I ref. to cellulose also has hydrogen bonds If mp 1 and 2 not stated allow one mark for amylose has α-glycosidic bond and cellulose has β-glycosidic bond 3 (cellulose) adjacent, monomers / glucose(s), rotated through 180° ; AW R ref. to heads / tails 4 amylose has an (energy) storage function v. cellulose has structural function / description relating to cell wall;
3. [5] (c) max 2 from mp 1 and 2 if transcription described or mix and match transcription and replication any five from: 1 DNA (double helix / molecule) unwinds ; I unzips R DNA, strand / a helix, unwinds 2 hydrogen bonds break between, base pairs / bases / strands ; A hydrogen bonds break between nucleotides only if clear that two strands are separated 3 both strands used as templates ; concise statement 4 DNA polymerase, qualified ; e.g. involved in polynucleotide formation / phosphodiester bond formation / catalyses synthesis R joins phosphates 5 ref. to (free) activated (DNA) nucleotides / AW ; A phosphorylated nucleotides R RNA nucleotides 6 complementary (DNA) nucleotides added ; R RNA nucleotides A described in terms of complementary base pairing A A pairs with T and C pairs with G 7 idea that process, occurs / continues, along whole DNA molecule ; 8 ref. to Okazaki fragments / movement of polymerase in one direction / nucleotides added in one direction ; A correct ref. to leading and lagging strands 9 each newly formed molecule contains one original and one newly synthesised strand ; 10 AVP; e.g. replication bubbles form / described ref. to repair / proofreading ref. to helicase (unwinding) / ligase (joining Okazaki fragments) in correct context R ligase joining phosphates process occurs, step-by-step / sequentially / AW ref. to RNA primers