BIOL 1000 - Chapter 1

Life

organized, requires materials and energy, has capacity to reproduce and develop, responds to its environment, maintains internal environment, has the ability to adapt

Atom

smallest unit of an element composed of electrons, protons, and neutrons

Molecule

union of two or more atoms of the same or different elements

Cell

the structural and functional unit of all living organisms

Tissue

a group of cells with a common structure and function

Organ

composed of tissues functioning together for a specific task

Organ System

composed of several organs working together

Levels of Biological Organization

atom - molecule - cell - tissue - organ - organ system

Levels of Biological Organization (2)

organism - species - population - community - ecosystem - biosphere

Organism

an individual

Species

a group of similar interbreeding organisms

Population

organisms of the same species in a particular area

Community

interacting populations in a particular area

Ecosystem

a community plus the physical environment

Biosphere

regions of the Earth’s crust, waters, and atmosphere inhabited by living organisms

Reproduction

the process by which an organism makes more of itself

Genes

units of information within an individual’s DNA that are pased to offspring during reproduction

DNA (deoxyribonucleic acid)

present in all organisms and directs cellular functions

Variations arises when

genes are recombined, expressed differently, or mutated

Organisms respond to external stimuli by

moving toward or away from the stimuli

Homeostasis

the requirement that organisms maintain a relatively constant internal environment

Adptations

features that make individual organisms better suited to a particular environment

Natural Selection

the differential reproductive success of adapted individuals

Natural selection results in

changes of characteristics of a population over time

Evolution

the chane in frequency of traits in populations and species

Living organisms are assigned groups based on

similarities

Taxonomy

the discipline of identifying and grouping organisms

Systematics

the study of the evolutionary relationships among organisms

Organism classifications

domain, kingdom, phylum, class, order, family, genus, species

Domains

the largest classification category

3 Domains

archaea, bacteria, eukarya

Archaea and bacteria include

unicellular prokaryotic cells

Prokaryotic cells

no nucleus

Eukarya include

eukaryotic cells

Eukaryotic cells

have a nucleus

Genes are found

within the nucleus of the cell