BIO 150 Foundations of Biology Flashcards (Ch. 1-5)

VOCABULARY flashcards covering key terms from BIO 150 Unit 1 lecture notes (Chapters 1–5).

Homeostasis

The regulation of an organism’s internal environment to maintain stability in the face of external changes.

Levels of biological organization

From smallest to largest: atoms, molecules, organelles, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystems, biosphere (smallest living level: cell).

Domains of life

Bacteria, Archaea, and Eukarya; Eukarya includes cells with nuclei.

Kingdoms of multicellular eukaryotes

Plantae, Fungi, and Animalia.

Qualitative data

Descriptive data that describes qualities without numerical measurements.

Quantitative data

Data expressed as numbers and measurements.

Hypothesis

A testable, falsifiable tentative explanation that can be evaluated by experiments.

Negative control

A group where no effect is expected, used to show that observed effects are due to the treatment.

Positive control

A group where a known effect is expected, used to show the experiment can detect effects.

Independent variable

The variable deliberately changed by the experimenter.

Dependent variable

The variable measured in response to the independent variable.

Theory

A well-supported explanation for a broad set of phenomena, founded on multiple tested hypotheses.

Matter

Anything that has mass and takes up space.

States of matter

Solid, liquid, and gas.

Element

A pure substance that cannot be broken down into simpler substances by chemical means.

Compound

A substance composed of two or more elements in a fixed ratio.

Four major biomass elements

Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N).

Atomic number

The number of protons in the nucleus; identifies the element.

Proton

Positively charged subatomic particle with mass ~1 amu; located in the nucleus.

Neutron

Electrically neutral subatomic particle with mass ~1 amu; located in the nucleus.

Electron

Negatively charged subatomic particle with negligible mass; located in electron shells around the nucleus.

Valence shell

Outer electron shell; determines bonding behavior.

Full valence shell

A complete outer shell (often 2 or 8 electrons) resulting in high stability and low reactivity.

Ionic bond

Bond formed by transfer of electrons resulting in oppositely charged ions attracted to each other.

Covalent bond

Bond formed by sharing electrons between atoms.

Single/double/triple bonds

Numbers of shared electron pairs: 1 (single), 2 (double), or 3 (triple).

Polar covalent bond

Unequal sharing of electrons due to electronegativity differences; creates partial charges on atoms.

Nonpolar covalent bond

Equal sharing of electrons; no partial charges.

Electronegativity

Attraction of a bonded atom for electrons; larger differences yield polar bonds.

Hydrogen bond

A weak attraction where a hydrogen covalently bonded to a highly electronegative atom is attracted to another electronegative atom.

Intermolecular forces

Forces between molecules (e.g., hydrogen bonds, dipole-dipole, London dispersion); hydrogen bonds are among the strongest in biology.

Chemical reaction notation

Reactants on the left, products on the right; arrow indicates direction; ⇌ indicates equilibrium.

Cohesion

Attraction between like molecules (e.g., water to water).

Adhesion

Attraction between unlike substances (e.g., water to glass).

Hydration shell

Layer of water molecules surrounding dissolved ions or molecules.

Solvent

The dissolving medium in a solution; in biology, typically water.

Solute

The substance dissolved in a solvent.

Solution

A homogeneous mixture of solvent and solute.

Dissociation of water

Water self-ionizes: H2O ⇌ H+ + OH−.

pH

A scale measuring how acidic or basic a solution is; 7 is neutral.

Buffer

A substance that resists changes in pH by neutralizing added acids or bases.