AP Biology Unit 1 A View of Life

Characteristics of Life RAREHOG Reproduction—life only comes from life (biogenesis) Adaptation, Evolution—life evolves as a result of interaction with the environment Response to the Environment—react to the actions going on around life Energy Utilization—Life takes in energy and transforms it to do many types of work. Homeostasis—Maintain a stable internal environment Order/Organization—emergent properties come from highly ordered structures Growth and Development—DNA directs growth and development or changes within an organism that is characteristic of that species

Each level of organization has emergent properties; Living Things Are Organized Each level of organization has emergent properties;   however, all new properties follow the laws of physics and chemistry.

Living Things Acquire Materials and Energy 1. Maintaining organization and carrying on life requires an outside source of energy (food, sunlight, chemicals) 2. Energy - capacity to do work; it takes work to maintain organization of the cell and organism. 3. Metabolism - all chemical reactions that occur in a cell. 4. Ultimate source of energy for nearly all life on earth is the sun 5. Organisms must maintain homeostasis -or keep themselves stable in temperature, moisture level, acidity, etc. by physiology and behavior

Living Things Respond 1. Living things interact with the environment in order to find nutrients or energy. 2. Responses to environment (stimulus) altogether constitute the behavior of an organism. Talking Parrot http://www.youtube.com/watch?v=sILtLDx99sQ&feature=player_embedded Penguins http://www.youtube.com/watch?v=q8Do6q-5Lvg&feature=player_embedded

Living Things Reproduce and Develop 1. Reproduction is the ability of an organism to make another organism like itself. 2. Bacteria, protozoans, and other unicellular organisms simply split into two  3. Multicellular organisms often unite sperm and egg  zygote 4. Genes are made of long molecules of DNA that specify how the organism is organized.

Living Things Have Adaptations This organism is called a pitcher plant. What do you think its adapted for? 1. Adaptations - modifications that make an organism suited to its way of life. 2. Natural selection is process by which species become modified over time. 3. Evolution is descent with modification.

Organisms Evolve through Natural Selection

How the Biosphere is Organized 1. The biosphere is the zone of air, land, and water where life is found. 2. A population consists of all members of one species in a particular area. 3. A community consists of all of the local interacting populations. 4. An ecosystem includes all aspects of a living community and the  physical environment, including   soils, atmosphere, etc. 5. Ecosystems are characterized by chemical cycling and energy flow. 6. Climate is the major determining factor of where ecosystems occur.

The Human Population Biodiversity 1. Humans modify ecosystems for our own purposes. 2. Some human activity threatens tropical rain forests and coral reefs. 3. Human beings depend on healthy working ecosystems for food, medicines, and raw materials. Biodiversity 1. Biodiversity consists of the total number of species, their variable genes, and their ecosystems. 2. Extinction is the death of a species or larger group; perhaps 400 species go extinct each day.

How Living Things Are Classified Taxonomy: the Discipline of Identifying and Classifying Organisms 1. Organisms are classified according to their evolutionary relationships. 2. As more is learned about organisms, the taxonomy changes.

Domains 1. Biochemical evidence breaks life into three domains: Bacteria, Archaea, and Eukarya. 2. Eukarya have a membrane-bounded nucleus. 3. The prokaryotes are structurally simple but have complex metabolisms. 4. Archaea vary from regular bacteria; all Archaea live in water, cannot tolerate oxygen, and have ability to survive harsh temperatures, salts, and acids similar to what was found on the primitive earth.

Kingdoms 1. The Archaea and Bacteria are not yet characterized into kingdoms. 2. Eukarya contains four kingdoms: Protista, Fungi, Plantae, and Animalia.

Scientific Method ObservationsQuestions HypothesisPrediction Test/ExperimentConclusion Uses controlled experiments with only one experimental variable

Observation 1. Scientists believe nature is orderly and measurable. 2. Science also considers that natural laws do not change with time. 3. Phenomena can therefore be understood from observations. 4. Actual science research may also involve chance (e.g., Alexander Fleming’s discovery of penicillin). *This principle of science is known as NATURAL CAUSALITY, by its nature it excludes supernatural phenomenon*

Hypothesis Examples of hypotheses, check those that are valid and can be tested: ____Bluebirds sing to attract mates. ____Bluebird songs are beautiful. ____Only male bluebirds sing. ____Sparrows will leave territories where they hear bluebirds sing. ____Bluebirds hate sparrows. A hypothesis is a possible explanation for a natural event - must be testable.

Inductive vs. Deduction Reasoning Inductive: Reasoning from a set of specific observations to reach a generalized conclusion. A generalization that summarizes observations Deductive: scientific method: Reasoning flows from general to specific. Predictions about what outcomes of experiments or observations we should expect if a particular hypothesis is correct.

Experiments/Further Observations 1. Testing a hypothesis involves either further observations or conducting an experiment. 2. Deductive reasoning involves “if, then” logic that predicts what will happen based on the hypothesis. 3. An experimental design is proposed that tests the hypothesis. 4. Scientists may use a model (global warming, but models are not always valid)  5. If a model cannot be tested, it always will remain a hypothesis.

Data You roll two dice, they both turn up ONEs.  This does not fit your prediction that you will only roll a ONE  1 out of 6 times.  Is the data significant enough to change your prediction? 1. Data are the results of experiments, and are observable and objective. 2. Data are often displayed in a graph or table. 3. Often the data must be inspected for the probability the data could show a relationship by chance; this is a measure of “significance.”

Conclusion 1. Whether the data support or reject the hypothesis is the basis for the “conclusion.” - avoid the word "prove"  2. The conclusion of one experiment can lead to the hypothesis for another experiment. 3. Science findings are reported in scientific journals so results are available to the research community (peer review). 4. The experiments and observations must be repeatable or the research is suspect. The Scientific Method http://www.youtube.com/watch?v=zcavPAFiG14&feature=player_embedded

Scientific Theory 1. The ultimate goal is to understand the natural world in scientific theories, conceptual schemes supported by a broad range of data. 2. The terms “principle” and “law” are also used for generally accepted theories. Basic theories of biology are: a. Cell theory: all organisms are made of cells. b. Biogenesis theory: life only comes from life. c. Evolution theory: living things have a  common ancestor and are adapted. d. Gene theory: Organisms contain  coded information that determines  their form, function, and  behavior.

Other Theories e. Germ Theory - proposes that microorganisms are the causes of many diseases f. Heliocentric Theory - the sun is the center of the solar system, planets revolve around the sun g. Law of Gravity - masses attract each other

A Controlled Study 1. Some investigations are managed where conditions can be kept constant a. A variable is a factor that can cause an observable change   b. The experimental variable is the step that is deliberately manipulated (ex.  nitrogen fertilizer). c. A dependent variable is component of an experiment that changes due to the experimental variable (growth).

Study I a. The hypothesis that pigeon peas will increase winter wheat production, compared to nitrogen fertilizer, is tested in clay pots using both treatments and a control group without treatment. b. Although both treatments exceed the control in wheat growth, the fertilizer-only treatment exceed the use of pigeon peas.

Study II a. To test the hypothesis that pigeon pea residues will build up over time and will increase winter wheat production, compared to nitrogen fertilizer, the test is continued. b. The fertilizer-only treatment no longer exceeded biomass production with the use of pigeon peas. c. All results and conclusions were then reported in a science journal.

Study III Observation: Babies are born with severe birth defects, mothers of these babies report taking the drug thalidomide during pregnancy for morning sickness. Question: Does thalidomide cause birth defects? Hypothesis: Thalidomide causes birth defects.

Experiment: Control group: Mice not given thalidomide during pregnancy Variable: Mice given thalidomide during pregnancy In this experiment, mice born from both the control and variable group will not have birth defects. This experiment was performed long before thalidomide was marketed and prescribed to pregnant women. Does these mean that the hypothesis is not supported?

Quick Review:  What is a Theory? Theories must explain a wide range of observations Theories must be falsifiable Theories can be changed if new evidence presents itself Generally, a THEORY explains the phenomenon  (WHY)  A  LAW defines it, or establishes a pattern  (WHAT) A Theory is an explanation for natural events that is based on a large number of observations. Can also be referred to as a PRINCIPLE or a LAW. Scientific Theories join together well supported and related hypotheses

Simply put: The simplest explanation is usually the correct one. What is Occam's Razor? Ockham's Razor (Occam is the latinized and more common spelling) is a principle proposed by William Ockahm in the 15th century. The original principle stated "Pluralitas non est ponenda sine neccesitate" which translates as "entities should not be multiplied unnecessarily" Simply put:  The simplest explanation is usually the correct one.