Module 1: How to Define Life The Nature of Biology Module 1: How to Define Life

How do you design an experiment? A. Problem/Purpose The question the lab will answer Identifies the independent and dependent variables Independent variable – the factor the scientist changes from group to group Dependent variable – the factor the scientist measures to see the effect of the independent variable Variables and Controls Videoclip

How do you design an experiment? B. Research/Background Information Lets the reader learn about the topic Helps the scientist develop an educated hypothesis C. Hypothesis An educated prediction Can be tested, proven false, and agrees with previous research

How do you design an experiment? D. Procedure/Experiment Steps must be precise and detailed Has one control group Normal conditions or absence of independent variable Used for comparison Experimental group(s) have only one changing variable (which is the independent variable)

How do you design an experiment? E. Observations/Data Must be objective. Good Example: The bacterial colony is yellow. Bad Example: The bacterial colony is nasty. Use measurements whenever possible. Good Example: There are 50 bacterial colonies. Bad Example: There are a whole bunch of colonies.

How do you design an experiment? E. Observations/Data Do not draw conclusions in the data section of the report. Good Example: There are bacteria and fungal colonies in the shoe section. Bad Example: The shoe was really dirty and so it was the most contaminated and grew a lot of stuff. Should be organized. May use a graph, table, or drawing(s). Always include units of measurement and a title.

How do you design an experiment? F. Analysis/Conclusions Answers the purpose question. Accepts or rejects the hypothesis. Explains what can be inferred from the data.

How do we know it is “good science”? A. Scientific knowledge must be shared, which allows other scientists to repeat and verify the work of others (peer review). A. Scientific knowledge is tentative. Theories are the most logical explanation based on current evidence, become stronger as more evidence is gathered, and give us a basis for prediction. Laws are universal generalizations that are virtually unchanging.

How do you know something is alive? A. Biology means the study of (-ology) all life (bio-) and includes many branches. B. Biologists organize living things into kingdoms. There are currently six kingdoms Kingdom Example Archaebacteria Extremophile bacteria Eubacteria Typical bacteria Protista Seaweed, Amoeba, Slime Mold Fungi Yeast, Mushrooms Plantae Moss, Fern, Holly, Oak tree Animalia , Fish, Birds, Frogs, Humans

How do you know something is alive? Characteristics of Life - Alive! Videoclip 1. Organization (The level of complexity) a. Organism Organ System Organs Tissues Cells Molecules Atoms / Elements Meet the Elements - They Might Be Giants

How do you know something is alive? All living things need six essential elements (atoms): Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur (CHNOPS) All living things are made of cells. One-celled organism – unicellular Many-celled organism - multicellular

How do you know something is alive? 2. Energy Use a. Organisms need energy constantly to build molecules (synthesis) and cells and to break down (digest) substances (such as breaking down food for nutrition) b. Organisms must transport nutrients to be used in cellular respiration to produce energy. c. An organisms’ chemical reactions are called its metabolism

How do you know something is alive? 3. Reproduction a. Organisms must replace themselves so the entire species will survive. b. May be asexual (only one individual contributes genetic material) or sexual (two individuals contribute genes).

How do you know something is alive? 4. Growth and Development a. Growth – to increase in size. Increases the number of cells of a multicellular organism. b. Development – change that takes place in structure and function of an organism during its life cycle. Example: Embryo becomes a fetus

How do you know something is alive? 5. Respond to Stimuli a. A quick, non-permanent change b. Stimulus – any condition that causes an organism to react. Example – A loud noise (stimulus) causes your dog to run under the bed (response).

How do you know something is alive? Adjust to Environment a.Homeostasis - the regulation of an organism’s internal environment to maintain conditions suitable for life Ex: Getting rid of wastes by excretion

How do you know something is alive? b. An adaptation is an inherited structure, behavior, or internal process that enables organisms to better survive an environment. Ex: Gills on a fish

Life Processes: STERNGRR Synthesis – making materials Transport – moving materials Excretion – getting rid of wastes Respiration – gas exchange AND production of energy (ATP) Nutrition – gaining and using energy from food Growth and Development – getting bigger and/or changing Regulation – controlling internal processes Reproduction – producing new cells or new organisms

What technology allows biologists to study microscopic life? A. Compound Light Microscope Has two lenses – ocular (eyepiece) and objective In order to be viewed, specimen must be thin (so the light may shine through the specimen) and placed on a slide. Specimen may be stained to better see structures

What technology allows biologists to study microscopic life? B. Electron Microscope Uses electrons to produce an image Types: Scanning Electron Microscope (SEM) Sends a beam of electrons across the object’s surface Produces a 3-D image Transmission Electron Microscope (TEM) Designed to look at structures inside a cell Capable of greatest magnification Eye of an ant

What technology allows biologists to study microscopic life? C. Limitations of microscopes Magnification is limited by the strength of the lens. Calculating magnification: Ocular lens x objective lens = total magnification Example: Ocular (10x) x objective (40x) = 400x As magnification increases resolution/(sharpness) decreases.