Many lost marks come from a single word: a student knows the process but uses a neighbouring term. This glossary gives each term a plain meaning, a small example and the word it is most often mixed up with.
Sixteen terms are grouped by topic, and each links to the topic that teaches it. The English, Malay and Chinese concept bridge shows the same terms in three languages.
Cells and movement
Diffusion. The net movement of particles from a region of higher concentration to a region of lower concentration, down a concentration gradient, using their own random movement. Example: the smell of cooking spreading across a room. Confused with osmosis. See movement across membranes.
Osmosis. The net movement of water molecules through a partially permeable membrane, from a dilute solution to a more concentrated one. Example: a potato cylinder gaining mass in pure water. Confused with diffusion, which applies to any particles and needs no membrane. See movement across membranes.
Active transport. Movement of particles against a concentration gradient, using energy from respiration. Example: root hair cells absorbing mineral ions from dilute soil water. Confused with diffusion, because both move particles across membranes. See movement across membranes.
Enzyme and substrate. An enzyme is a biological catalyst, and the substrate is the substance it acts on. Example: amylase acts on starch. Confused with each other, and with the product. See biological molecules and enzymes.
Denatured and dead. An enzyme is a protein, not a living thing, so it is denatured, not killed. High temperature changes the shape of its active site, so the substrate no longer fits. Confused with “the enzyme died”. See biological molecules and enzymes.
Energy, gas exchange and transport
Photosynthesis and respiration. Photosynthesis builds glucose using light energy and happens in plants. Respiration releases energy from glucose and happens in all living cells. Confused with each other, as if they were opposites in time, such as “plants respire at night only”. See plant nutrition and gas exchange and respiration.
Respiration and breathing. Respiration is a chemical process inside cells. Breathing moves air in and out of the lungs. Example: you breathe faster because your muscle cells respire faster. Confused with each other, because everyday speech uses one word for both. See gas exchange and respiration.
Transpiration and translocation. Transpiration is the loss of water vapour from leaves, pulling water up the xylem. Translocation is the movement of sucrose and amino acids in the phloem. Confused with each other because both begin with trans. See plant transport.
Artery and vein. An artery carries blood away from the heart, and a vein carries blood towards it. The pulmonary artery carries deoxygenated blood, so “artery means oxygenated” is wrong. Confused with each other, and with oxygen content. See circulation and blood.
Excretion, egestion and secretion. Excretion removes waste made by the body’s own chemical reactions, such as urea. Egestion removes undigested food as faeces. Secretion releases a useful substance, such as an enzyme. Confused with each other, especially excretion and egestion. See excretion and homeostasis.
Inheritance and variation
Gene, allele and chromosome. A chromosome carries many genes. A gene is a length of DNA coding for a protein. An allele is one version of a gene. Example: the gene for seed shape has a round allele and a wrinkled allele. Confused with each other, because all three sit in the nucleus. See cell division and inheritance.
Genotype and phenotype. The genotype is the alleles an organism has, such as Aa. The phenotype is the observable feature that results, such as tall. Confused with each other, because the same phenotype can come from two genotypes. See cell division and inheritance.
Dominant and recessive. A dominant allele shows in the phenotype even with one copy. A recessive allele shows only when two copies are present. Confused with “common”, since dominant does not mean more frequent. See cell division and inheritance.
Mitosis and meiosis. Mitosis makes two genetically identical cells and is used for growth and repair. Meiosis makes gametes with half the chromosome number and with variation. Confused with each other, because both divide the nucleus. See cell division and inheritance.
Natural selection and adaptation. Natural selection is the process by which individuals with helpful features survive and pass on their alleles. An adaptation is the feature that helps. Confused with an individual “trying” to change. See variation and selection.
Ecology and investigations
Habitat, population, community and ecosystem. A habitat is where an organism lives. A population is one species in an area. A community is all the populations. An ecosystem includes the community and its non-living surroundings. Confused with each other, because all describe groups in one place. See ecology and energy flow.
Independent, dependent and control variables. The independent variable is the one you change, the dependent one is what you measure, and control variables are kept the same. Example: changing the temperature and measuring the time for a reaction. Confused with each other when a question asks “what was kept constant”. See data and investigations.
How to use this glossary
Pick one pair a day. Write a one-line meaning for each, add your own example, and say aloud why the other word does not fit. Then answer a short question that needs the right word.
If a pair keeps causing errors, add it to your mistake log and revisit the topic with the original practice hub. The Biology learning guide gives the wider map.
Language choice matters less than precision. In online one-to-one Biology tuition, a teacher can ask you to explain each term in your own words and notice when a neighbouring word slips in.