📖 Biology Glossary

Electrical impulse along a neuron triggered when sodium ions rush into the cell.

Tiny air sacs in the lungs where gas exchange occurs — oxygen in, carbon dioxide out.

Protein produced by B cells that binds specifically to antigens to neutralize pathogens.

Adenosine triphosphate — the primary energy currency of cells, produced during cellular respiration.

Complete sequence of events in one heartbeat: systole (contraction) and diastole (relaxation).

Volume of blood pumped per minute: Heart Rate × Stroke Volume. Normal resting ~5 L/min.

Passive movement of particles from high to low concentration — no energy required.

Process by which DNA copies itself during the S phase before cell division — semi-conservative mecha...

System of glands that secrete hormones into the bloodstream to regulate metabolism, growth, and repr...

Biological catalyst (usually protein) that speeds up chemical reactions without being consumed.

The tendency of biological systems to maintain stable internal conditions despite external changes.

Cell division that halves chromosome number, producing four genetically unique haploid cells for rep...

Cell division producing two identical daughter cells through prophase, metaphase, anaphase, and telo...

Regulatory mechanism that reverses a change to maintain homeostasis — e.g., insulin lowering blood s...

Specialized cells that transmit electrical and chemical signals throughout the nervous system.

Movement of water through a semipermeable membrane from low to high solute concentration.

Pressure required to stop osmosis across a semipermeable membrane; determined by solute concentratio...

Process by which plants convert light energy into glucose using carbon dioxide and water.

Basic unit of a muscle fiber; actin and myosin filaments slide past each other to produce contractio...

Junction between two neurons where neurotransmitters cross the synaptic cleft to transmit signals.