Chapter 1 – The Study of Life Biology – The study of life and living organisms Organism – Anything capable of carrying on all of the processes of life Branches of biology – There are many subtopics within biology – a few examples we’ll hit upon this year:

Biochemistry – Chemical substances and processes in organisms Genetics – Inheritance – passing of traits from one generation to next  Evolution – Change in organisms over time  Cell biology/cytology – Cell structure and function  Zoology – Animals  Anatomy – Structures of organisms  Physiology – Functions, activities, and processes of organisms  Ecology – Interactions of organisms and environment

Characteristics of Life – Life is diverse yet all organisms share a set of characteristics: 1.Living things are organized – levels of organization vary In general: atoms  molecules  cells  tissues  organs  organ systems  organisms Cells are the smallest unit of life

 Multicellular organisms (more than 1 cell) will have the above system based on jobs cells perform (although some organisms may not have complex organs or systems – more primitive, ex: sponge)  Cells in these organisms are considered specialized (have certain jobs)  Examples: some fungus, plants, and animals

 Unicellular organisms (one cell) will be organized up to the cellular level  1 cell does all jobs for organism  Examples: bacteria, protists, and some fungus

2.Living things acquire materials and energy  Metabolism – all the chemical reactions in cell  Heterotrophs are organisms that obtain nutrients from food eaten Ex: some bacteria and protists, fungus, & animals

 Autotrophs are organisms that make their own food through photosynthesis  Take CO 2, H 2 O, and solar energy to make glucose, a simple sugar that can be used as a source of energy  Ex: plants, some protists, and some bacteria

3.Living things reproduce  Reproduction – production of offspring  Prevents extinction of species  Uses DNA (hereditary information) – which can be copied  Can be sexual or asexual

Asexual reproduction – used by unicellular and some multicellular organisms; only 1 parent; offspring has DNA identical to parent Sexual reproduction – used by multicellular organisms; 2 parents, each parent contributes ½ genetic information to offspring; offspring has mixed traits from parents

4.Living things respond to stimuli Stimuli is external May be seen as movement, such as movement away from danger, or reactions to other organisms. Behavior – observable, coordinated responses to environmental stimuli Examples: plant growing toward light, hair raising on back of cat’s neck, pupils dilating in response to light

5. Living things are homeostatic  Homeostasis – maintaining (relatively) constant internal conditions (such as body temperature, pH, blood pressure, water balance) regardless of external changes  Examples of homeostatic behavior: sweating or shivering to maintain body temperature; urinary system ridding body of wastes

6. Living things grow and develop  Growth – an increase in the number of cells/ increase in the size  Occurs through cell division and enlargement; part of development  Example – getting taller  Development – Changes an organism undergoes between conception and death  Example – going throughpuberty

7. Living things are adapted  Adaptations – modifications that make an organism suited to its way of life  Examples – hollow bones of birds for flight, gills for fish to breathe in water

 Adaptations come about through evolution – a process through which a species changes over time  This is the source of the diversity of life  Organisms do not develop adaptations during the course of their lives

Classification Taxonomy – The study of identifying and classifying organisms according to specific criteria Taxa –the categories into which organisms are classified

Why do we need scientific names? Common names don’t tell you enough information What kind of frog? Is it poisonous??? Common names are misleading Jellyfish – you mean it’s not a fish? Ringworm – what do mean it’s not a worm? Common names vary from country to country Mountain lion, cougar and puma all refer to the same animal

Early classification system Designed by Aristotle Everything was classified as either a plant or an animal Failed to include bacteria, fungus and protists Failed to show proper relationships between organisms Too general – classified by where they lived (air, land or water)

Modern system of classification :  Binomial nomenclature (2 names)  Developed by Carolus Linnaeus in the 18 th century  Grouped according to their presumed evolutionary relationship  Those placed in the same genus will be most closely related, those in different domains most distantly related  Ex: Those in genus Felis are more closely related to each other than organisms in the domains Eukarya and Archaea are to each other.

The taxa: Domain Kingdom Phylum (Division for plants) Class Order Family Genus Species Did King Phillip Come Over For Good Spaghetti????

Domain Archaea –  Unicellular prokaryotes  May have been first cells  Live in aquatic environments that lack oxygen or are too salty, too hot, or too acidic for most other organisms – like primitive Earth(?)

Domain Bacteria  Unicellular prokaryotes  Found almost anywhere – in soil, water, atmosphere, on and inside living organisms

Domain Eukarya  Cells contain membrane-bound nucleus  Four Kingdoms within –  Protists (Protista)  Fungus (Fungi)  Plants (Plantae)  Animals (Animalia)

Writing scientific names: Ex: Homo sapiens or Homo sapiens Can be abbreviated H. sapiens  If typed – should be italicized.  If handwritten – should be underlined.  First word is genus – capitalized  Second word is specific epithet of species within a genus – lower case