Grade 8 Science: Cells, Living Things, Cell Theory, Microscopes, Diffusion & Osmosis

Four characteristics of living things

1. Has a life span, 2. Is made out of cells, 3. Grows and reproduces, 4. Responds to the environment.

Unicellular organism

An organism composed of only one cell; example: paramecium.

Multicellular organism

An organism composed of multiple cells; example: plant.

Autotroph

Organisms that obtain energy through photosynthesis.

Heterotroph

Organisms that obtain energy by consuming nutrients from their environment.

Sexual reproduction

Reproduction that requires two parent cells.

Asexual reproduction

Reproduction that requires only one parent cell.

Stimulus

A signal to which living things can respond; examples: sound, light.

Waste produced by living things

Examples include carbon dioxide from breathing and excretion.

Matthias Schleiden

A scientist who proposed that all parts of plants are made up of cells.

Theodore Schwann

A scientist who proposed that animals are made entirely of cells.

Robert Hooke

A scientist known for discovering cells, allowing scientists to see them for the first time.