All scientific notation, units, and formulae are now displayed using standard HTML entities and text for perfect compatibility.
Mitosis
A type of cell division that results in two daughter cells each having the same number of chromosomes as the parent cell. Used for growth and repair.
[Image of the stages of Mitosis]
Meiosis
A type of cell division that produces four genetically different haploid cells (gametes). Used for sexual reproduction.
Translocation
The movement of dissolved food (sugars) produced during photosynthesis from the leaves to other parts of the plant via the phloem.
Transpiration
The process of water evaporation from the surface of a plant, mainly through the leaves, which creates a pull for water movement (transpiration stream).
Eukaryotic / Prokaryotic Cells
Eukaryotic cells have a membrane-bound nucleus (e.g., animal/plant cells). Prokaryotic cells lack a nucleus (e.g., bacteria).
Homeostasis
The maintenance of a constant internal environment (e.g., temperature, blood sugar) in an organism.
Covalent Bond
A strong bond formed by the sharing of electrons between atoms, typically between non-metals.
Ionic Bond
A strong electrostatic attraction between oppositely charged ions, formed by the transfer of electrons (typically metal and non-metal).
Ion / Isotope
An Ion is a charged atom (lost/gained electrons). An Isotope is an atom with the same protons but different neutrons.
Mole
The unit for the amount of substance, equal to 6.02 × 1023 particles (Avogadro's constant).
Catalyst
A substance that speeds up a chemical reaction by lowering the activation energy but is not used up in the process.
Dynamic Equilibrium
In a reversible reaction, when the rate of the forward reaction equals the rate of the reverse reaction.
Conductor / Insulator
A Conductor allows energy (heat/electricity) to flow easily (e.g., metals). An Insulator resists energy flow (e.g., plastic).
Transverse Wave
A wave where oscillations are perpendicular (90°) to the direction of energy transfer (e.g., light).
[Image of a transverse wave diagram]
Moment
The turning effect of a force about a pivot. Calculated as Force × Perpendicular distance.
[Image of calculating moment of a force]
Resistance
The opposition to the flow of electric current in a circuit. Measured in Ohms (Ω).
Momentum
The product of an object's mass and its velocity. Measured in kg m/s.
Half-life
The time taken for the number of radioactive nuclei in a sample to halve.
Independent Variable (IV)
The one variable that is deliberately changed (manipulated) by the scientist in an investigation.
Dependent Variable (DV)
The variable that is measured (recorded) because it changes as a result of the changes to the IV.
Control Variable (CV)
A variable that must be kept the same throughout the investigation to ensure a fair test. [Image illustrating types of variables in an experiment]
Uncertainty
The interval or range within which the true value is expected to lie (often shown as ± the smallest scale reading).
Repeatable / Reproducible
Repeatable: Same person/method obtains same results. Reproducible: Different people/methods obtain same results.
Mastering these verbs tells you exactly how to structure your answer for maximum marks:
State / List
Give a specific word, term, or short answer. Usually 1 mark and requires no justification.
Describe
Set out the characteristics or give an account of something. Often requires a sequence of events or a structural overview. Usually 2-3 marks.
Explain
Set out the reasons for something happening. Requires a link between the cause and the effect, often using the word 'because' or 'leading to'. (e.g., Explain why the rate increases).
Compare
Identify the similarities AND differences between two or more things. Must reference both things in the answer. (e.g., Compare mitosis vs. meiosis).
Evaluate
Look at the strengths, weaknesses, advantages, and disadvantages of something. Requires a judgement or conclusion (e.g., Evaluate the method for measuring speed).
Devise
Higher-order thinking; requires you to plan or invent a method to investigate a problem. Needs clear steps and control measures.