Accelerated Biology Unit 1 Study Guide

A comprehensive vocabulary review of Unit 1 Accelerated Biology covering experimental design, biochemistry, classification, cladograms, and evolution.

Independent variable

The variable in an experiment that is deliberately manipulated or changed by the experimenter.

Dependent variable

The variable in an experiment that is observed or measured to see how it responds to changes in the independent variable.

Controlled variables

All conditions and factors kept constant throughout an experiment to ensure an unbiased and fair test.

Control group

The baseline group in an experiment that does not receive the experimental treatment and serves as a comparison.

Experimental group

The group in a scientific investigation that receives the specific variable or condition being tested.

If…then…because hypothesis

A formal scientific hypothesis structure stating the proposed cause, the predicted outcome, and the underlying biological or chemical reasoning.

Proton

A subatomic particle located in the nucleus with a positive charge ($+1$) and a mass of approximately $1\,\text{amu}$.

Neutron

A subatomic particle located in the nucleus with a neutral charge ($0$) and a mass of approximately $1\,\text{amu}$.

Electron

A subatomic particle located in the electron cloud outside the nucleus with a negative charge ($-1$) and negligible mass.

Atom

The basic, defining unit of a chemical element consisting of a positively charged nucleus surrounded by orbiting electrons.

Isotope

An atom that has the same number of protons as other atoms of the element, but a different number of neutrons.

Ion

An atom or molecule that has gained or lost one or more electrons, resulting in a net positive or negative charge.

Electronegativity

The measure of an atom's tendency to attract a shared pair of electrons toward itself in a chemical bond.

Nonpolar covalent bond

A chemical bond formed when electrons are shared equally between two atoms with similar electronegativity values.

Polar covalent bond

A chemical bond formed when electrons are shared unequally between atoms due to differences in electronegativity, creating partial charges.

Ionic bond

A chemical bond formed through electrostatic attraction between oppositely charged ions following the complete transfer of valence electrons.

Hydrogen bonding

An intermolecular attraction between a partially positive hydrogen atom in a polar covalent bond and an electronegative atom in a nearby molecule.

Cohesion

The property of water molecules sticking to other water molecules via hydrogen bonding.

Adhesion

The attraction between water molecules and other polar or charged surfaces.

Surface tension

The measure of the force required to stretch or break the surface of a liquid, heightened in water due to cohesive hydrogen bonds.

Heat capacity of water

The amount of heat energy required to change the temperature of water, which is high because heat must first break hydrogen bonds.

Heterotroph

An organism that cannot synthesize its own food and must obtain nutrients and energy by consuming other organisms.

Asexual reproduction

A reproductive process involving a single parent that produces offspring genetically identical to the parent.

Intron

A non-coding sequence of DNA or pre-mRNA that is removed during RNA splicing before protein synthesis.

Virus

A biological entity that subverts the characteristics of living things by utilizing a host cell for replication and metabolic functions.

DKPCOFGS

The hierarchy of taxonomic classifications from most inclusive to most specific: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Species

The most specific taxonomic group, consisting of individuals capable of interbreeding and producing viable, fertile offspring.

CER

A scientific writing format consisting of Claim, Evidence, and Reasoning used to explain phenomena or support conclusions.

Cladogram

A branching diagram used in cladistics to display hypothetical evolutionary relationships between taxa based on shared characteristics.

Monophyletic

A taxonomic group that includes an ancestral species and all of its direct evolutionary descendants.

Polyphyletic

A grouping of organisms that includes taxa originating from different ancestors, excluding their most recent common ancestor.

Ancestral trait

A trait inherited from an ancient common ancestor that is shared by multiple related taxa in a cladogram.

Derived trait

A novel trait that evolved relatively recently within a specific lineage and distinguishes it from ancestral groups.

Outgroup

A taxon or lineage on a cladogram that serves as a reference group when determining evolutionary relationships among the ingroup.

Clade

A monophyletic group on a phylogenetic tree that contains a common ancestor and all of its descendants.

Node

A branching point on a cladogram that represents a divergence event and the most recent common ancestor of descendant lineages.

Natural selection

The evolutionary mechanism in which organisms possessing advantageous traits for their environment survive and reproduce at higher rates.

Common ancestry

The evolutionary concept that different species share a common ancestral lineage from which they have diverged.

Convergent evolution

The evolutionary process wherein unrelated organisms independently evolve similar traits due to adapting to similar selective pressures or environments.

Divergent evolution

The process by which interbreeding species diverge into two or more descendant species, typically becoming more morphologically distinct over time.