01
Cells & energy
Cells use specialized structures and chemical processes to maintain life.
- Cell membranes regulate movement of substances.
- Ribosomes build proteins.
- Mitochondria are major sites of cellular respiration in eukaryotic cells.
Edvora/Science
SUBJECT HUB
Science
Biology, chemistry, and physics references built around models, evidence, and cause-and-effect reasoning.
CORE TOPICS
Build the foundation.
These are concise review notes—not a replacement for your course textbook or teacher’s instructions.
02
Genetics
DNA carries hereditary information, while gene expression helps connect genotype to traits.
- Genotype refers to allele combinations; phenotype refers to observable traits.
- Punnett squares model probabilities, not guarantees.
- Mutations and recombination contribute to variation.
03
Evolution & ecology
Population change over generations is shaped by heritable variation and environmental pressures.
- Natural selection acts on variation within populations.
- Food webs model transfers of matter and energy.
- Changes in one part of an ecosystem can affect many other parts.
04
Atomic structure
Matter is built from atoms whose structure explains many chemical patterns.
- Atomic number = number of protons.
- Neutral atoms have equal numbers of protons and electrons.
- Isotopes of an element differ in neutron count.
05
Chemical reactions
Balanced equations represent conservation of atoms during chemical change.
- Change coefficients to balance equations, not subscripts in formulas.
- Mole ratios come from coefficients in a balanced equation.
- Mass is conserved in a closed system.
06
Motion
Describe motion using position, velocity, and acceleration, then connect equations to graphs.
- Average speed = distance / time
- Average velocity = displacement / time
- Acceleration = change in velocity / time
07
Forces & energy
Net force changes motion; energy tracks the ability of systems to cause change.
- Newton’s second law: F = ma
- Kinetic energy: KE = ½mv²
- Near Earth, gravitational potential energy: PE = mgh
08
Scientific reasoning
Good science distinguishes observations, models, uncertainty, and conclusions.
- Identify independent and dependent variables.
- Use controls when they help isolate a cause.
- A conclusion should match the strength of the evidence.
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