Evolution, Themes of Biology, and the Chemical Context of Life

A set of vocabulary flashcards covering the characteristics and organization of living things, taxonomy, scientific method, basic chemistry, and the biological properties of water.

Biology

The scientific study of living things.

Biosphere

The portion of Earth that supports life, encompassing all ecosystems.

Ecosystem

A biological community of living organisms interacting together with their physical, nonliving environment.

Community

All the populations of different species that live and interact together within a defined area.

Population

A group of individuals belonging to the same species living in the same geographic area.

Organism

An individual living thing, representing a single member of a population.

Cell

The smallest functional unit of life, enclosed by a membrane or cell wall.

Tissue

A group of similar cells that work together to perform a specific function.

Organ

A structure composed of two or more types of tissues working together to carry out a specific task.

Organ System

A group of organs working together to carry out a broad set of body functions.

Homeostasis

The ability of an organism to regulate and maintain stable internal conditions despite fluctuating external conditions.

Asexual Reproduction

A form of reproduction involving a single parent that passes an exact copy of its genes to offspring, producing genetic clones.

Sexual Reproduction

A form of reproduction involving two parents passing half of their genes to offspring via gametes, producing genetically varied offspring.

Adaptation

Any inherited structure or behavior that enhances an organism's fitness and survival in a specific environment.

Taxonomy

The branch of biology concerned with naming and classifying species into hierarchical groups.

Binomial Nomenclature

The two-word scientific naming system in Latin consisting of the Genus name followed by the specific epithet.

Domain Bacteria

A domain of microscopic, unicellular prokaryotes representing the most diverse and widespread organisms.

Domain Archaea

A domain of unicellular prokaryotes that often inhabit extreme environments such as boiling hot springs and salty lakes.

Domain Eukarya

The domain comprising all eukaryotic organisms (protists, fungi, plants, and animals) with complex cells containing a nucleus.

Independent Variable

The single factor intentionally changed or manipulated by the researcher in an experiment.

Dependent Variable

The factor or response measured to generate data in an experiment in response to changes in the independent variable.

Control Group

The experimental baseline group that is kept under normal or baseline conditions for comparison.

Scientific Theory

A broad explanation of a fundamental aspect of the natural world supported by extensive and varied empirical evidence.

Matter

Anything that has mass and occupies physical space.

Element

A basic substance that cannot be broken down into simpler substances; $92$ occur naturally.

CHNOPS

An acronym for Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur, which constitute $98\%$ of living matter.

Atom

The smallest unit particle of an element that retains the chemical properties of that element.

Proton

A subatomic particle carrying a positive charge located within the atomic nucleus.

Neutron

A subatomic particle carrying no charge (neutral) located inside the atomic nucleus.

Electron

A subatomic particle carrying a negative charge located outside the atomic nucleus.

Atomic Number

The specific number of protons contained in the nucleus of an atom.

Mass Number

The combined total number of protons plus neutrons in an atom's nucleus.

Atomic Mass Number

The average mass calculated across all naturally occurring isotopes of an element.

Isotopes

Atoms of the same element that share the same atomic number but possess differing numbers of neutrons.

Radioisotopes

Unstable isotopes that emit radiation ranging from low to high levels during radioactive decay.

Valence Shell

The outermost electron shell of an atom, determining its chemical reactivity and bonding behavior.

Octet Rule

The chemical principle that an atom's valence shell is stable when filled with $8$ electrons.

Compound

A substance composed of two or more different chemical elements combined in fixed proportions by chemical bonds.

Electronegativity

A measure of an atom's ability to attract and pull electrons toward itself within a chemical bond.

Ionic Bond

A chemical bond resulting from electrostatic attraction between oppositely charged ions created by electron transfer.

Covalent Bond

A strong chemical bond formed when nonmetal atoms share one or more pairs of valence electrons.

Polar Covalent Bond

A covalent bond formed between atoms with different electronegativities, leading to unequal electron sharing and partial charges.

Nonpolar Covalent Bond

A covalent bond in which valence electrons are shared equally between atoms with similar electronegativity.

Hydrogen Bond

A weak intermolecular attraction between a slightly positive hydrogen atom in a polar molecule and a slightly negative atom in another.

Hydrophilic

Refers to polar or ionic 'water-loving' substances that readily dissolve in or interact with water.

Hydrophobic

Refers to nonpolar 'water-fearing' substances that do not mix with or dissolve in water.

Amphipathic

Describes a molecule containing both a polar (hydrophilic) region and a nonpolar (hydrophobic) region, such as soap.

Cohesion

The intermolecular attraction between like molecules, causing water molecules to stick to one another via hydrogen bonding.

Adhesion

The attraction between unlike molecules, causing water to stick to other polar surfaces.

Surface Tension

A measure of how difficult it is to stretch or break the surface of a liquid, caused by cohesive forces.

Capillary Action

The upward movement of liquid through narrow spaces against gravity driven by combined cohesive and adhesive forces.

Specific Heat

The quantity of heat energy required to raise the temperature of $1\,g$ of a substance by $1\,^\circ\text{C}$.

Heat of Vaporization

The amount of heat energy required to convert a liquid into a gas; for water, this equals $540\,cal/g$.

Acid

A substance that dissociates in water to release hydrogen ions ($H^+$), such as $HCl \rightarrow H^+ + Cl^-$.

Base

A substance that reduces hydrogen ion concentration by releasing hydroxide ions ($OH^-$) or binding $H^+$, such as $NaOH \rightarrow Na^+ + OH^-$.

pH Scale

A logarithmic scale ranging from $0$ to $14$ indicating the relative concentration of hydrogen ions in solution.

Buffer

A chemical system that minimizes pH changes by taking up or releasing hydrogen ions, such as the bicarbonate buffer system $H_2CO_3 \rightleftharpoons H^+ + HCO_3^-$.