OCR A 2.1.2(a)–(j) · 20 written questions · 46 marks · about 55 minutes · marked as you go
This free quiz has 20 written exam questions on water, carbohydrates and lipids, all taken from OCR A Level Biology A papers (AS and A level, 2018 to 2025). Short answers and calculations mark themselves. For longer answers you write your answer, then tick off the OCR mark-scheme points you made, so you see exactly where the marks are. The quiz covers the first half of OCR A 2.1.2 Biological molecules: why water's properties matter to living things, monomers and polymers, the elements in biological molecules, carbohydrates from glucose to cellulose, and the structure, formation and roles of triglycerides and phospholipids.
What the quiz covers (OCR A spec 2.1.2(a)–(j))
Water (2.1.2(a)): hydrogen bonding, cohesion and adhesion in xylem transport, and how density and specific heat capacity make water a good habitat.
Monomers, polymers and elements (2.1.2(b)(c)): classifying biological molecules as monomers or polymers, and which elements are found in proteins.
Monosaccharides and glycosidic bonds (2.1.2(d)(e)): α- and β-glucose, ribose as a pentose, maltose, and making and breaking glycosidic bonds by condensation and hydrolysis.
Starch, glycogen and cellulose (2.1.2(f)(g)): comparing their structures, and linking the properties of glucose and polysaccharides to their roles in cells and plant cell walls.
Triglycerides and phospholipids (2.1.2(h)–(j)): saturated and unsaturated fatty acids, ester bonds and hydrolysis, how phospholipids form membranes, and the functions of triglycerides.
How to use it
Write every answer in full, as you would in the exam: the mark for each question is shown, so you know how much to write. When you self-mark, only tick a point if your answer clearly makes it, then read the examiner's tip under each question. Your progress is saved on your device, so you can do it in two sittings, and at the end you can retry just the questions where you dropped marks.
Prefer multiple choice? Try the 27-question Carbohydrates multiple choice quiz first.
Open the Water, Carbohydrates and Lipids quiz in a new tab (easier on a phone)
Where students lose marks (from OCR examiners' reports and mark schemes)
Each point below is followed by wording that gained marks.
Say water molecules, not water: Answers about transport in the xylem say 'water sticks together' or 'water forms a column' without mentioning molecules or the xylem.
✔ Gains credit: Cohesion: hydrogen bonds hold water molecules together, so a column of water molecules is pulled up the xylem; adhesion makes water molecules stick to the xylem vessel walls.
Three ester bonds, three waters: When explaining hydrolysis of a triglyceride, students rarely say how many bonds break, and some call them glycosidic or phosphodiester bonds.
✔ Gains credit: Water is used to break the three ester bonds, splitting the three fatty acids from the glycerol.
Kinks, not hydrogen bonds: Students think fatty acids with more hydrogen atoms have higher melting points because they form more hydrogen bonds.
✔ Gains credit: Fewer hydrogen atoms means more C=C double bonds, so the chains are kinked and the molecules can't pack closely together, giving a lower melting point.
Polyunsaturated means more than one: Students say a polyunsaturated fatty acid has a double bond or a kink, missing the 'poly'.
✔ Gains credit: It has more than one C=C double bond, so more than one kink in the chain (and fewer hydrogen atoms).
Specific heat capacity in full: 'High heat capacity' or 'specific latent heat' is written when explaining why water is a stable habitat, and OCR ignores both.
✔ Gains credit: Water has a high specific heat capacity, so its temperature stays stable.
Tensile strength, not just strong: Students describe cellulose as 'strong', 'rigid' or 'permeable', or describe the cell wall instead of the cellulose molecule.
✔ Gains credit: Cellulose is insoluble, unreactive (inert), flexible and has a high tensile strength.
Say which kind of insulation: Single-word answers such as 'insulation' or 'warmth' don't earn marks for the functions of triglycerides.
✔ Gains credit: Thermal insulation, electrical insulation, buoyancy, energy storage, respiratory substrate, physical protection (e.g. around the kidneys).
Explain why the bilayer forms: Asked how phospholipid structure allows membranes to form, students describe membrane structure instead of explaining it.
✔ Gains credit: The phosphate head is hydrophilic and the fatty acid tails are hydrophobic, so the heads face the water and the tails face each other, away from the water, forming a bilayer.
Keep practising
Try the Carbohydrates multiple choice quiz, the Lipids and Cholesterol quiz, the Cell Structure and Microscopy written quiz or the Proteins, Ions, Food Tests and Chromatography written quiz, or browse all our OCR A Level Biology quizzes. Our OCR A masterclasses (Year 12 on Wednesdays at 5.15pm, Year 13 on Tuesdays at 6.30pm) work through real exam questions on one topic each week.
Questions, mark schemes and examiners' report extracts © OCR.