Download clean, printable lists of the most common mistakes students make — so you can fix them before they cost marks.
Each sheet is aligned to its exam board and built from recurring student errors highlighted in examiner reports and mark schemes.
What you get
A topic-by-topic mistakes list with a “do this instead” fix and a quick self-check.
How to use it
Review before past papers, then use the quick checks to catch errors under timed conditions.
Why it works
Many marks are lost on predictable slips: rounding, sign errors, units, and misreading commands.
Coverage by topic
Preview (up to 5 per topic)
14 total rows in download
| Topic | Common mistake / misconception | Do this instead | Quick check |
|---|---|---|---|
| Cell Biology | Confusing the terms 'cell' and 'organelle'. | Cell = the basic unit of life. Organelle = a specialised structure INSIDE the cell (e.g. mitochondrion, ribosome). The cell contains organelles. | Organelles are INSIDE the cell. The cell is the whole unit. |
| Cell Biology | Saying osmosis and diffusion are the same process. | Diffusion: any molecule, down concentration gradient, no membrane required. Osmosis: water ONLY, through a partially permeable membrane, from high to low water potential. | Osmosis = water only + membrane. Diffusion = any substance, no membrane needed. |
| Enzymes | Saying boiling permanently destroys the substrate. | High temperature denatures the ENZYME (changes active site shape). The substrate is unchanged. The enzyme can no longer bind to the substrate. | Denaturation affects the ENZYME (active site). Substrate is unaffected. |
| Nutrition | Saying humans absorb food in the stomach. | Most absorption occurs in the SMALL INTESTINE (ileum), which has villi and microvilli for large surface area. Stomach digests but absorbs little (only alcohol, some drugs). | Absorption: small intestine (villi). Digestion: stomach + small intestine. |
| Photosynthesis | Stating plants only photosynthesise in daylight. | Plants photosynthesise whenever light is available — this can include artificial light. They respire continuously (day and night). | Photosynthesis: when light is present. Respiration: always continuous. |
| Respiration | Confusing breathing rate with rate of respiration. | Breathing rate = number of breaths per minute (physical process). Rate of respiration = rate of chemical energy release in cells. They are related but different. | Breathing (physical) ≠ respiration (chemical). Both increase with exercise. |
| Gas Exchange | Saying alveoli exchange gas with blood directly. | O₂ diffuses from alveoli → into blood plasma → into red blood cells → binds haemoglobin. CO₂ diffuses out in reverse. State the full pathway. | O₂: alveolus → blood → RBC → Hb. CO₂: Hb → blood → alveolus → exhaled. |
| Genetics | Forgetting to show gametes in genetic crosses. | Always show: parent genotypes → gametes (with circle) → Punnett square → offspring genotypes and phenotypes with ratios. | Genetic cross: parents → gametes → Punnett square → offspring ratio. |
| Genetics | Confusing dominant allele with common allele. | Dominant = expressed in heterozygote. It has nothing to do with frequency in the population. Recessive alleles can be MORE common in some populations. | Dominant = expressed when present. Frequency in population is unrelated. |
| Ecology | Saying the food web shows energy STORAGE. | Food webs show the FLOW/TRANSFER of energy between organisms. Energy is not stored in the web — it is released at each trophic level (mostly as heat). | Food web: shows energy TRANSFER (arrows point from eaten to eater). |
| Ecology | Saying humans are always at the top of every food chain. | Humans are omnivores and appear at different trophic levels depending on what they eat. A human eating plants is at level 2; eating fish that eat algae is at level 3. | What level depends on what the organism eats — check the specific food chain. |
| Disease | Saying all microbes cause disease. | Most microbes are harmless or beneficial (e.g. gut bacteria, nitrogen-fixing bacteria). Only PATHOGENS (specific bacteria, viruses, fungi, protists) cause disease. | Pathogen = disease-causing microorganism. Most microbes are not pathogens. |
| Homeostasis | Saying insulin converts glucose to starch. | Insulin stimulates liver and muscle cells to convert excess glucose to GLYCOGEN (animal storage carbohydrate), not starch (plant storage). | Animals store carbohydrate as GLYCOGEN (liver/muscle). Starch = plant storage. |
| Reproduction | Confusing sexual and asexual reproduction advantages. | Sexual: genetic variation (adaptation advantage long-term). Asexual: faster, no mate needed, all offspring can reproduce (short-term advantage in stable environments). | Sexual → variation (good for changing environments). Asexual → rapid reproduction (stable environments). |