Biology Fundamentals: Life, Classification, and Scientific Inquiry

Biology

The study of life.

Cell

The smallest unit that is still considered alive.

Homeostasis

A constant balancing act, maintaining internal conditions such as blood glucose, oxygen, carbon dioxide, and acidity within a viable range.

Biotic

Refers to living components of an ecosystem.

Abiotic

Refers to nonliving components of an ecosystem.

Atom

The smallest unit of matter.

Biological Organization Hierarchy

Atom $\to$ Molecule $\to$ Organelle $\to$ Cell $\to$ Tissue $\to$ Organ $\to$ Organ system $\to$ Organism $\to$ Population $\to$ Community $\to$ Ecosystem $\to$ Biosphere.

Ecosystem

Communities together, which include biotic (living) and abiotic (nonliving) components, i.e., the living and nonliving aspects of the environment.

Biosphere

The collection of all ecosystems on Earth.

Taxonomy

The scientific classification system for organisms, utilizing Latin-based names developed by Carl Linnaeus.

Carl Linnaeus

The historical figure responsible for developing the standard system of scientific names (binomial nomenclature).

Binomial Nomenclature

The system of scientific naming using genus and species, such as $\textit{Homo sapiens}$.

Domains of Cellular Life

Bacteria, Archaea, and Eukaryota.

Eukaryota Kingdoms

Animalia, Plantae, and Fungi.

Chordata

A major phylum within the animal kingdom for animals possessing a spinal cord.

Scientific Method Steps

Observation $\to$ Question $\to$ Hypothesis $\to$ Experiment $\to$ Data $\to$ Conclusion (often includes Research and Repeatability).

Repeatability

Essential in the scientific method to confirm whether results are reliable and reflect real phenomena or chance.

Hypothesis

A testable explanation for a phenomenon; a tentative answer that can be tested and, if new data emerge, can be revised or discarded.

Theory

A hypothesis that has been repeatedly tested and has withstood extensive scrutiny with little change; well-supported by extensive evidence but open to revision.

Law

A principle that can be completely explained by mathematics; common in physics and chemistry (rare in biology).

Independent Variable

The factor that is deliberately changed in an experiment.

Dependent Variable

The data or outcome that is measured and reported in an experiment.

Constants

Factors held fixed across all groups in an experiment to prevent confounding influences.

Positive Control

A group in an experiment expected to show the effect; demonstrates what the outcome looks like when the phenomenon occurs.

Negative Control

A group in an experiment not expected to show the effect; shows what it looks like when it does not occur.

Confounding Variable

Occurs when multiple factors change in tandem, making it difficult to determine which factor caused an observed effect.

If-Then Statement (Hypothesis)

Articulates a predicted causal relationship: if a certain action is taken, then a specific outcome will occur.

Null Hypothesis

A hypothesis predicting no effect.

Alternative Hypothesis

A hypothesis predicting an effect.

Typical Human Body Temperature

$T_{\text{body}} \approx 98.6 \,^\circ F \approx 37 \,^\circ C.$