Grade 9 Biology Key Terms

These flashcards cover key terms and their definitions from Grade 9 Biology, including concepts related to cell biology, diffusion processes, and components of the circulatory system.

Osmosis

Movement of water through a selectively permeable membrane from an area of high water concentration to low water concentration (does not require energy).

Selectively Permeable Membrane

A membrane (barrier) that lets certain molecules through (like water) but not other molecules (like solutes such as sugar or salt).

Diffusion

Movement of molecules from an area of high concentration to an area of low concentration (no energy required).

Lysosomes

Contains enzymes which can digest things such as old organelles in the cell.

Ribosomes

Used to make proteins by assembling amino acids in the correct order.

Golgi Body

Sorts and processes proteins, deciding which proteins are transported outside the cell and which remain, packing them into vesicles.

Endoplasmic Reticulum

Folding proteins into the correct shape and putting them in vesicles to transport them to the Golgi body.

Vesicles

Move molecules around the cell.

Mitochondria

Produces energy for the cell.

Carbohydrates

Composed of C, H, O; contains sugar molecules; used as an energy store.

Lipids (fats)

Composed of C, H, O; used as energy storage or insulation.

Proteins

Composed of C, H, O, N and sometimes S; have many functions including enzymes and muscle repair.

Nucleic Acids

Composed of C, H, O, N, P; used for storing genetic material in DNA & RNA.

Equilibrium

State where concentrations are equal.

Concentration Gradient

Occurs when the concentration of particles is higher in one area than another.

Facilitated Diffusion

Molecules diffuse across the plasma membrane with assistance from membrane proteins, moving down a concentration gradient.

Active Transport

Requires energy; molecules move from low concentration areas to high concentration areas.

Transpiration

Evaporation inside the leaf through the stomata to the atmosphere.

Hypotonic

Lower solute concentration, higher water concentration.

Isotonic

Equal solute and water concentrations.

Hypertonic

Higher solute concentration, lower water concentration.

Phagocytes

A type of white blood cell that ingests and digests pathogens in a process called ‘phagocytosis.’

Lymphocytes

A type of white blood cell that produces antibodies and is specific.

Arteries

Carry blood away from the heart; have thick muscular walls to withstand high pressures.

Capillaries

Are a single cell thick; allow for diffusion of molecules in and out.

Veins

Carry blood towards the heart.