CH 1: The Scientific Study of Life

Atom

The smallest unit of matter.

Molecule

A group of atoms bonded together (e.g., water, DNA).

Organelle

A functional structure inside cells (e.g., nucleus, mitochondria).

Cell

The basic unit of life.

Tissue

A group of similar cells performing a specific function.

Organ

A structure made of different tissues that work together (e.g., heart, lungs).

Organ System

A group of organs that work together (e.g., digestive system).

Organism

A single living individual.

Population

A group of organisms of the same species in one area.

Community

All populations (different species) in one area.

Ecosystem

A community plus its non-living environment (air, water, soil).

Biosphere

The sum of all ecosystems on Earth.

Emergent Property

A characteristic that arises at a higher level of organization that wasn't present at the lower levels.

Order

Organized structure in cells and organisms.

Regulation (Homeostasis)

Maintaining a stable internal environment.

Growth and Development

Organisms grow and change over time.

Energy Processing

Using energy to function (e.g., metabolism).

Response to Stimuli

Reacting to environmental changes.

Reproduction

Producing offspring.

Evolution and Adaptation

Changes over generations due to natural selection.

Energy

The capacity to do work (e.g., sunlight, food).

Nutrient

A substance required for growth and survival.

Producers

Organisms (plants, algae) that make their own food using sunlight.

Consumers

Organisms that eat producers or other consumers.

Receptors

Proteins or cells that detect stimuli.

DNA (Deoxyribonucleic Acid)

The molecule that carries genetic instructions.

Traits

Inherited characteristics (e.g., eye color, height).

Inheritance

The passing of genetic traits from parents to offspring.

Development

Changes that occur during an organism's life cycle.

Genus

The first part of the name, capitalized (e.g., Homo in Homo sapiens).

Species

The second part, lowercase, unique to the organism (sapiens in Homo sapiens).

Prokaryotes

No nucleus (Bacteria & Archaea).

Eukaryotes

Have a nucleus (Eukarya: plants, animals, fungi, protists).

Bacteria

Single-celled, no nucleus, found everywhere.

Archaea

Single-celled, no nucleus, live in extreme environments.

Eukarya

Have a nucleus, includes plants, animals, fungi, and protists.

Protists

Unicellular or simple multicellular organisms (e.g., algae).

Fungi

Decomposers (e.g., mushrooms, yeast).

Plants

Multicellular, photosynthetic organisms.

Animals

Multicellular consumers that move.

Observation

Noticing a phenomenon.

Question

Asking why or how it happens.

Hypothesis

A testable explanation.

Experiment

Testing the hypothesis.

Data Collection

Gathering results.

Analysis

Interpreting data.

Conclusion

Supporting or rejecting the hypothesis.

Communication

Sharing results for peer review.

Scientific Theory

A well-supported explanation backed by extensive evidence.

Variable

A factor that can change in an experiment.

Independent Variable

The factor that is changed (cause).

Dependent Variable

The factor that is measured (effect).

Experimental Group

The group that receives the treatment.

Control Group

The group that does not receive the treatment, used for comparison.

Hypothesis to Theory

A hypothesis becomes a scientific theory when it has been repeatedly tested, supported by strong evidence, and widely accepted in the scientific community.