Biology: Properties of Life

Study Notes

Biologists seek to understand the fundamental properties of life, their functions, organization, diversity, and origins.

Order: Organisms exhibit highly organized structures, with all life composed of one or more cells.
Sensitivity or response to environment: Organisms react to external stimuli, such as plants bending towards light or bacteria moving towards or away from chemical or light sources.
Reproduction: Living organisms create offspring through DNA replication, ensuring the continuation of their species.
Adaptation: Organisms evolve to fit their environment through natural selection; for example, heat-resistant Archaea bacteria adapt to harsh environments.
Growth and Development: Organisms grow and develop according to genetic instructions, inheriting traits from their parents.
Regulation/Homeostasis: Organisms maintain a stable internal environment (homeostasis) despite external changes, using regulatory mechanisms. Examples include human body temperature regulation and freshwater fish maintaining salt balance.
Energy Processing: All organisms utilize energy sources, converting sunlight or food into chemical energy.
Evolution: Organisms adapt to changing environments through mutations and genetic changes, resulting in diversity.

Prokaryotic Cells: Single-celled organisms lacking membrane-bound organelles and a nucleus.
Eukaryotic Cells: Can be single-celled or multicellular, possessing membrane-bound organelles and a nucleus enclosed by a nuclear membrane.

Tissue: A group of similar cells carrying out similar functions.
Organ: A collection of tissues working together for a specific function.
Organ System: A higher-level organization of organs cooperating for related functions.
Organism: An individual living entity.

Population: All individuals of a species within a specific area.
Community: The sum of all populations within an area.
Ecosystem: All living organisms and their non-living environment within a defined area.
Biosphere: The collection of all ecosystems on Earth, encompassing land, water, and the atmosphere.

Domain: The highest level of classification, encompassing major groups of organisms.
Kingdom: A subdivision of Domain, grouping organisms with shared characteristics.
Phylum: Further subdivision of Kingdom, grouping organisms with more specific traits.
Class: Subdivision of Phylum, grouping organisms with even more specialized traits.
Order: Subdivision of Class, grouping organisms with closely related features.
Family: Subdivision of Order, grouping closely related genera.
Genus: A group of closely related species.
Species: A group of organisms capable of interbreeding and producing fertile offspring.