Introduction to Biology Studying Life’s Diversity and Intricate Processes

Biological Inquiry  Bio = of living things (life)  Biological Science: observation, identification, experimental investigation and theoretical explanation of natural phenomena  What are the Characteristics of Living Things?  How Do Biologists Study Living Things?

Characteristics of Living Things?  Composed of cells  Levels of organization  Use energy and metabolism  Response to environmental changes  Growth and development  Reproduce  Adapt to their environment (evolution)

1. Living Things are Composed of Cells  Two types of cells  Prokaryotic  Archaea and Bacteria  few internal membranes  no membrane-bound nucleus  Eukaryotic  Protists, Fungi, Animals, Plants  extensive internal membranes  membrane-bound nucleus

2. Organizational Levels of Life Most Complex Least Complex sub-atomic particles atom molecule macromolecule organelle cell tissue organ organ system organism population community ecosystem biosphere protons, neutrons, electrons nitrogen nucleotide DNA nucleus neuron nervous tissue brain nervous system fish school of fish coral reef populations coral reef (living + nonliving) inhabitable regions of earth

3. Energy Use and Metabolism  Energy = ability to do work  Energy conversion = change of one form of energy to another  Metabolism = sum of chemical reactions in an organism

Alfalfa leaves oriented toward sunlight to maximize photosynthesis Desert plant leaves oriented vertically to minimize water loss 4. Response to Environmental Changes

 Living things maintain homeostasis = a relatively stable internal condition regulation and homeostasis response to environmental changes

Feedback mechanisms regulate biological systems

 Growth = increase in size  Development = change in characteristics 5. Growth and Development

6 Reproduce

Adapt To Their Environment 1. Adjustments may occur by natural selection, as individuals with favorable genetic traits breed more prolifically than those lacking these traits (genotypic adaptation), 2. Or they may involve non-genetic changes in individuals, such as physiological modification (e.g. acclimatization) or learned behavioral changes (phenotypic adaptation). Adaptation – adjustments made by animals in response to their environments.

Scientific Method

 Hypothesis-based Science  Ask Questions or make Observations  Formulate an Hypothesis: tentative answer to well-framed question  Make Predictions based on hypothesis  Test Predictions by Conducting Experiments  Analyze experimental data  Determine whether data supports hypothesis

An Hypothesis will haveAn Hypothesis will have –Two measurable variables –Precise relationship between them (relationship = prediction) The relationship between DNA content and length of the cell cycle is a direct proportion.

 A good hypothesis is  Testable  experiments can be designed to test predictions from the hypothesis  experimental results must be repeatable  Falsifiable  allows scientists to eliminate alternative hypotheses

Testing hypothesesTesting hypotheses –Controlled Experiment test designed to determine the effect of one factor while keeping all other factors constanttest designed to determine the effect of one factor while keeping all other factors constant experimental = sample treated to test for effect of the factor being studiedexperimental = sample treated to test for effect of the factor being studied control = sample treated like experimental in all ways EXCEPT for the factor being studiedcontrol = sample treated like experimental in all ways EXCEPT for the factor being studied

Supported Hypotheses Supported Hypotheses Theory = broad explanation of a natural phenomenon that has been supported by a large body of evidenceTheory = broad explanation of a natural phenomenon that has been supported by a large body of evidence Principle or Law = theory that has been supported over a long period of timePrinciple or Law = theory that has been supported over a long period of time –Cell Principle All living things are composed of cells and cell products; all cells come from pre-existing cells.All living things are composed of cells and cell products; all cells come from pre-existing cells.