Themes in Biology Advanced Biology

Definition of Biology Biology means the “study of life” –Allows scientists to examine the natural world Interactions between each other How organisms change over time –Many sub-branches of biology Organism –Living things (bacteria, protists, plants, fungi, animals) are considered to be organic beings; non-living things are inorganic –Estimated between 8.7 million (6.5 on land and 2.2 in the oceans) on Earth; we have identified roughly 1.2 million thus far

Building Blocks of Life All living things exhibit a high degree of organization Basic building block is a cell –Made of atoms  macromolecules  organelles –Blood, bone, muscle cells Cells combine to form tissues –Group of cells with common structures and functions –Muscle, connective, epithelial, and nervous tissue

Building Blocks of Life Tissue combine to form organs –Group of tissues that work together to perform a certain task –Heart, lungs, stomach Organs will combine to form organ systems –Several organs that work together –Cardiovascular, digestive Organ systems will form an organism

Six Major Components All living things are composed of cells –Unicellular One celled organisms (Bacteria, Amoeba, Paramecium) Can live and function independently –Multicellular Organisms composed of more than one cell Undergo cell differentiation or specialization for a certain job

Six Major Components Organisms must maintain homeostasis to survive –Organisms stabilize internal conditions (homeostasis) despite their changing external environment –Body will adjust to maintain homeostasis Body temperature Water levels in body

Six Major Components Living organisms must receive a constant supply of energy –All chemical reactions that occur in an organism are known as metabolism –Autotrophs: Make own food (energy) from sunlight(photosynthesis) –Heterotrophs: Must intake food for energy

Six Major Components Living organisms also have the ability to respond to different stimuli (changes in the environment) –Can be internal or external (light source), can be physical or chemical –Helps to ensure the organism’s survival

Six Major Components Reproduction allows for the survival of the species, not the individual –Process of creating more organisms like themselves –Parents pass genes (DNA) to offspring –Sexual reproduction Requires two organisms to reproduce (conjugation-in bacteria and some protistians) –Asexual reproduction Requires only one organism to reproduce (binary fission, budding)

Six Major Components All organisms will have adaptations that help them to survive –Traits or characteristics that improve chances of survival –Allows for diversity within populations Natural selection-organisms with favorable traits will survive to pass on those traits to their offspring Populations change over time (not individuals

Living Organisms Believe first life forms on Earth appeared billion years ago during the Paleozoic era –Was probably some form of bacteria that could grow, reproduce, and evolve –Miller-Urey experiment—1950s Sent an electric current (lightening) through methane and ammonia (gases thought to be in the primordial or “early” atmosphere) Reaction created amino acids or organic molecules that make up our bodies today _miller-urey_experiment.html

Miller-Urey Experiment

CLEs Biology –3.1.C.a (DOK 1)