Biology Concepts 1.1 What is life?

What is life?  Living things vs. nonliving objects:  Comprised of the same chemical elements  Obey the same physical and chemical laws  The cell is the smallest, most basic unit of all life  Familiar organisms are multicellular  Some cells independent – single-celled organisms

What are emergent properties?  Levels range from extreme micro to global  Each level up:  More complex than preceding level  Properties:  A superset of preceding level’s properties  Emerge from interactions between components

What are the basic requirements of all living things?  Three requirements  Materials and Energy  Reproduction and Development  Adaptations and Natural Selection  Energy - the capacity to do work  The sun:  Ultimate source of energy for nearly all life on Earth  Drives photosynthesis  Metabolism - all the chemical reactions in a cell  Homeostasis - Maintenance of internal conditions within certain boundaries  Acquiring nutrients

What are the basic requirements of all living things?  Living things detect changes in environment  Response often involves movement  Vulture can detect and find carrion a mile away  Monarch butterfly senses fall and migrates south  Microroganisms follow light or chemicals  Even leaves of plants follow sun  Responses collectively constitute behavior

What are the basic requirements of all living things?  Organisms live and die  Must reproduce to maintain population  Multicellular organisms:  Begins with union of sperm and egg  Developmental instructions encoded in genes  Composed of DNA  Long spiral molecule in chromosomes

What are the basic requirements of all living things?  Adaptation  Any modification that makes an organism more suited to its way of life  Organisms, become modified over time  However, organisms very similar at basic level  Suggests living things descended from same ancestor  Descent with modification - Evolution  Caused by natural selection

Biological Concepts 1.2 Taxonomy and Systematics

What is taxonomy?  The rules for identifying and classifying organisms  Hierarchical levels (taxa) based on hypothesized evolutionary relationships  Levels are, from least inclusive to most inclusive:  Species, genus, family, order, class, phylum, kingdom, and domain  A level usually includes more species than the level below it, and fewer species than the one above it

How are organisms classified?

What are the three domains?  Bacteria  Microscopic unicellular prokaryotes  Archaea  Bacteria-like unicellular prokaryotes  Extreme aquatic environments  Eukarya  Eukaryotes – Familiar organisms

What are the kingdoms?  Archaea –  Kingdoms still being worked out  Bacteria –  Kingdoms still being worked out  Eukarya  Kingdom Protista  Kingdom Fungi  Kingdom Plantae  Kingdom Animalia

What are scientific names?  Binomial nomenclature (two-word names)  Universal  Latin-based  First word represents genus of organism  Second word is specific epithet of a species within the genus  Always Italicized as Genus species (Homo sapiens)  Genus may occur alone (Homo), but not specific epithet

Biological Concepts 1.3 Scientific method

What is the scientific method?  Begins with observation  Scientists use their five senses  Instruments can extend the range of senses  Hypothesis  A tentative explanation for what was observed  Developed through inductively reasoning from specific to general

What is the scientific method?  Experimentation  Purpose is to challenge the hypothesis  Designed through deductively reasoning from general to specific  Often divides subjects into a control group and an experimental group  Predicts how groups should differ if hypothesis is valid  If prediction happens, hypothesis is unchallenged  If not, hypothesis is unsupportable

What is the scientific method?  Results  Observable, objective results from an experiment  Strength of the data expressed in probabilities  The probability that random variation could have caused the results  Low probability (less than 5%) is good  Higher probabilities make it difficult to dismiss random chance as the sole cause of the results

What is the scientific method?  The results are analyzed and interpreted  Conclusions are what the scientist thinks caused the results  Findings must be reported in scientific journals  Peers review the findings and the conclusions  Other scientists then attempt to duplicate or dismiss the published findings

What is a scientific theory?  Scientific Theory:  Joins together two or more related hypotheses  Supported by broad range of observations, experiments, and data  Scientific Principle / Law:  Widely accepted set of theories  No serious challenges to validity

What types of experimental variables are there?  Experimental (Independent) variable  Applied one way to experimental group  Applied a different way to control group  Response (dependent) variable  Variable that is measured to generate data  Expected to yield different results in control versus experimental groups