Biology Test 1 Study Guide

Cell Theory

A fundamental biological principle stating that all living organisms are composed of one or more cells and that all cells arise from preexisting cells.

Homeostasis

The process by which living organisms maintain relatively stable internal physical and chemical conditions.

Metabolism

The sum of all chemical processes that maintain life within an organism, including catabolic and anabolic reactions.

Negative Feedback Loop

A primary homeostatic mechanism in which a change in a variable triggers a response that counteracts the initial change, such as blood sugar regulation.

Endocytosis

A cellular process in which substances are brought into the cell by engulfing them in a vesicle formed from the cell membrane.

Capsid

The outer protein coat that surrounds and protects the genetic material of a virus.

Virion

A complete, structurally intact, and infectious virus particle located outside a host cell.

Lytic Cycle

A viral replication path that proceeds through attachment, penetration, synthesis, assembly, and host cell lysis to release new viruses.

Lysogenic Cycle

A viral replication path where viral DNA integrates into the host chromosome and replicates alongside the host cell without immediately destroying it.

Antibiotic Action

Medications designed to kill or inhibit bacteria by targeting bacterial structures (like cell walls), making them ineffective against non-cellular viruses.

Monophyletic Group

A phylogenetic group (clade) that includes a single common ancestor and all of its descendants.

Paraphyletic Group

A phylogenetic group consisting of a common ancestor and some, but not all, of its descendants.

Convergent Evolution

The process by which unrelated organisms independently evolve similar traits due to adapting to similar ecological niches or selective pressures.

Homologous Structures

Anatomical traits in different species that are similar because they were inherited from a common ancestor.

Law of Parsimony

A scientific principle stating that when evaluating phylogenetic trees, the hypothesis requiring the fewest evolutionary changes is preferred.

Microevolution

Changes in allele frequencies within a population over generations.

Macroevolution

Major evolutionary change occurring over long geological time scales, resulting in the origination of new species or higher taxonomic groups.

Genetic Drift

Random changes in allele frequencies within a population due to chance events.

Gene Flow

The transfer of genetic variation and alleles between populations through migration and interbreeding.