Characteristics of Life & the Scientific Method

Cellular organization, metabolism (uses energy), homeostasis, growth and development, reproduction, response to stimuli, and evolution/adaptation over generations.

Maintaining stable internal conditions despite changes outside — e.g., your body holding ~37 °C by sweating, shivering, and adjusting blood vessels.

It uses energy, grows, and can 'reproduce,' but it has no cells, no DNA, no homeostasis, and no evolution — life must show ALL the characteristics.

Viruses have genetic material and evolve, but they have no cells and no metabolism of their own — they can only copy themselves by hijacking a host cell.

Atoms → molecules → organelles → cells → tissues → organs → organ systems → organism → population → community → ecosystem → biome → biosphere.

A population is one species in one place; a community is all the populations together; an ecosystem adds the nonliving parts (soil, water, sunlight).

It is a testable, falsifiable proposed explanation that predicts something — not just a guess. 'Plants like music' isn't testable; 'plants given 8 hrs of music daily grow taller than plants in silence' is.

Independent = what YOU deliberately change (hours of music). Dependent = what you measure, which depends on it (plant height in cm).

Everything kept the same across all groups — soil type, pot size, water volume, light, temperature, seed variety — so only one factor differs.

The control group gets no treatment and serves as the comparison baseline; without it there's nothing to measure the treatment's effect against.

Observe → question → hypothesize → test → analyze → revise → share — it's a repeating loop, not a rigid one-time ritual.