Study of Life Chapter 1 Themes AP Biology Study of Life Chapter 1 Themes 2007-2008

Biology is a subject of enormous scope AP Biology Biology is a subject of enormous scope Studying the diverse forms of life reveals common themes in Biology

Themes in biology Science as a process of inquiry AP Biology Themes in biology Science as a process of inquiry questioning & investigation Evolution Hierarchy and emergent properties The cellular basis of life Relationship of structure to function Energy transfer Continuity & Change Regulation Interdependence and interactions in nature Science, technology & society

Science as a process of inquiry AP Biology Science as a process of inquiry

Common theme of the scientific process Hypothetico-deductive thinking The first part refers to hypothesis which is a tentative answer to some question (an explanation on trial) Ex. Maybe eating a big lunch just before going to history every day makes Scott sleepy

The deductive refers to the use of deductive reasoning to test hypothesis, Deduction contrasts with induction. Induction is reasoning from a set of specific observations to reach a general conclusion (as in all organisms are composed of cells)

Deduction the reasoning flows reverse from induction from the general to the specific. In the scientific process deduction usually takes the form of predictions about the results of experiments or observations we should expect if a particular hypothesis (premise) is correct.

This deductive testing takes the form of “ If……..then logic EX. If Scott eats before History class, then he will be sleepy in class.

Hypotheses Are Possible explanations Should reflect past experience Multiple hypothesis should be proposed whenever possible Should be written as if ….then (the if is the independent variable and the then is the dependent variable) Should be testable via the hypothetico-deductive approach.

Can be eliminated but not confirmed with absolute certainty.

Science as a process of inquiry AP Biology Science as a process of inquiry Built on repeatable observations & testable, falsifiable hypotheses

"Nothing in biology makes sense except in the light of evolution." AP Biology "Nothing in biology makes sense except in the light of evolution." Theodosius Dobzhansky: Integrating Genetics and Evolution Theodosius Dobzhansky, a Russian geneticist who moved to the United States, provided laboratory evidence for natural selection and variation where previously there had been only field observation. Dobzhansky's work with Drosophila, or fruit flies, provided new evidence that supported Darwin's theory that natural selection, acting on genetic variation in populations, is a driving force in evolution. -- Theodosius Dobzhansky March 1973 Geneticist, Columbia University (1900-1975) 2007-2008

AP Biology Natural selection Evolutionary change is a product of the process of natural selection –can produce new species

The origin of species Charles Darwin presented two ideas: Current species arose from a succesion of ancestors through “decent with modification “ (evolution) The mechanism of evolution is natural selection He observed this by Individuals in a population of any species vary in many heritable traits Any population can potentially produce far more offspring than the environment can support Result of these 2-> a struggle for existence among variant members of a population

AP Biology Evolution explains unity & diversity (all life is connected through evolution) Unity what do organisms have in common & why do similarities exist? common biochemistry & physiology evolutionary relationships connected through common ancestor Diversity but why are there differences? natural selection adaptations allow different individuals to survive in different environments

AP Biology

Organizing systems Taxonomy is the study of classification AP Biology Organizing systems Taxonomy is the study of classification Making sense out of the diversity Hierarchical scheme Eastern gray squirrel Sciurus carolinensis

3 Domains of Life Bacteria, Archaea, Eukarya Bacteria Archaea Eukarya AP Biology 3 Domains of Life Bacteria, Archaea, Eukarya Bacteria Archaea Eukarya

Life’s Hierarchical Order (atoms), (organelles) Cells Tissues Organs Organism Population * Community * Ecosystem * Emergent properties

Emergent Properties: Novel properties which result from interactions between components. An organism is a living whole, greater than the sum of its parts. Reductionism vs. systems biology

Properties of life Order Reproduction Growth and development Energy utilization Response to environment Homeostasis Evolutionary adaptaions

The Cellular Basis of Life Prokaryotes vs. Eukaryotes Prokaryotes do not have DNA enclosed in a nucleus or membrane-bound structures. Eukaryotes do have DNA enclosed in a membrane bound nucleus and include membrane bound organelles.

Examples of Cells

Form follows function (cell is the smallest unit of life) AP Biology Form follows function (cell is the smallest unit of life) The alignment of structure & function is seen at all levels of biology Form fits function organ organism cell organelle

Energy transfer Life is an open system need input of energy AP Biology Energy transfer Life is an open system need input of energy energy flows through energy comes in, energy goes out need a constant input need input of materials nutrients are recycled around & around nutrients ENTROPY RULES! DECOMPOSERS RULE, too!

You think they’re eating… They’re harvesting energy! AP Biology Energy utilization You think they’re eating… They’re harvesting energy!

AP Biology Continuity & change Continuity of life is based on heritable information in the form of DNA DNA – the genetic material – carries biological information from one generation to the next T R A I

AP Biology Regulation Organisms need to maintain a “steady state” in the face of changing conditions maintain homeostasis achieve this through feedback monitor the body like a thermostat turn on when it’s needed, off when its not

Interdependence and Interactions AP Biology Interdependence and Interactions No organism is an island standing alone communities, ecosystems

Science, technology & society AP Biology Science, technology & society Science & technology must function within the rules of society ethics

4 Big Ideas (Themes) in AP Biology Big Idea 1: The process of evolution drives the diversity and unity of life.

Big Ideas in AP Biology Big Idea 2: Biological systems utilize free energy and molecular building blocks to grow, to reproduce and to maintain dynamic homeostasis.

Big Ideas in AP Biology Big Idea 3: Living systems store, retrieve, transmit and respond to information essential to life processes.

Big Ideas in AP Biology Big Idea 4: Biological systems interact, and these systems and their interactions possess complex properties.