Chemistry 20
Mole ratio
Coefficients count particles, not grams.Common errorUsing coefficients as a mass ratio is the single most expensive error in the unit.
Biology 20
Biomagnification
Concentration rising UP the food chain, level by level.Common errorBioaccumulation — that is buildup inside ONE organism. Magnification is across levels.
English 20-1
Controlling idea
Your claim. One sentence, arguable, and every paragraph must serve it.Common errorThe topic. “Isolation” is a topic. It claims nothing, so it cannot control anything.
English 20-1
Text creator
The person who MADE the text. A writer, a film-maker, a photographer.Common errorThe narrator — that is a voice the text creator invented.
Biology 20
NP = GP − R
Net primary production. The plant burns some of what it makes just staying alive.Common errorConsumers eat NET, never gross. Using GP is the classic error.
Math 20-1
Root / zero / x-intercept
Three names, one idea — the x values where y = 0. The exam swaps between them freely.