Cells contain carbohydrates, proteins, lipids and nucleic acids. (a) Fig. 5.1 is a list of biological molecules, some of which are components of larger molecules. [Figure 5.1] Complete Table 5.1 by using only the molecules listed in Fig. 5.1. • Each example can be written under one or more correct headings. • All the examples in Fig. 5.1 should appear at least once in Table 5.1. [Table 5.1]

Mark scheme

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

1. [5] glycine in monomer column only;
2. monomer: thymine (nucleotide), α-glucose, β-glucose, glycine
3. polymer: cellulose, messenger RNA, glycogen, α-globin
4. monosaccharide: α-glucose, β-glucose
5. polysaccharide: cellulose, glycogen
6. I incorrect spellings
7. if α-globin appears once and is in monomer column instead of polymer column, and the monomer and polymer columns are otherwise correct, allow one mark (ecf)
8. [3] any three from:
9. allow points from an annotated diagram
10. 1 phosphate head = hydrophilic / polar;
11. 2 fatty acid / hydrocarbon, tail / chains = hydrophobic / non-polar;
12. if mps 1 and 2 not gained, allow one mark for, hydrophilic/polar, heads and, hydrophobic/non-polar, tails
13. 3 (so) heads face, watery environment / tissue fluid / cytoplasm / cytosol / aqueous environment ;
14. 4 (fatty acid) tails, form hydrophobic core / form area away from water / face each other / AW ;
15. 5 ref. tails and hydrophobic interactions ;