Chapter 1: The Study of Life Biology Mrs. Haase

Biology Study of life Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. Biologists recognize that all living things share certain characteristics

Characteristics of Life 1. Have an orderly structure All living things made of one or more cells Cells are the smallest unit capable of all life functions

Characteristics of Life 2. Reproduction The production of offspring Species A group of organisms that can interbreed and produce fertile offspring.

Characteristics of Life 3. Growth and Development Increase in the amount of living material and the formation of new structures DNA directs pattern of growth and development

Characteristics of Life 4. Response to the Environment Environment includes air, water, weather, temperature other organisms in the area and other factors Examples? Stimulus and Response S: Anything in the organism’s internal or external environment that causes it to react R: A reaction to a stimulus

Characteristics of Life Responses to the internal environment---Homeostasis Maintenance of internal conditions suitable for survival despite changes in external conditions homestudy.ihea.com/wildlifeID/0 43jackrabbit.htm

Characteristics of Life Orderly structure Growth and Development Response to the environment Reproduction

Characteristics of Life Accomplishing 1-4 requires energy! All energy originates from the sun Plants convert solar energy into sugar Animal use/store energy in own tissues

Characteristics of Life Adaptation Any inherited structure, behavior or internal process that promotes the likelihood of an organism’s survival and reproduction. Evolution Genetic change of a population or species over time (generations)

Chapter 1 Section 2 The Methods of Biology

Science explains nature through Observations Setting up experiments Creating representative models Scientific Method: the common steps that scientists use to gather information and answer questions.

Scientific Method Observations Question Hypothesis Prediction Experiment Data Conclusion Retest Communicate Results Flashlight failure

Observation You observe something in the material world, using your senses or machines which are basically extensions of those senses. AH—Look at this!

Question You ask a question about what you observe. State the problem or question.

Hypothesis An explanation for a question or a problem that can be formally tested. Based on research You should be able to give reasons for why you chose your hypothesis If/then… statement

Experiment You figure out a way to test whether the hypothesis is supported through an investigation Control group– the standard group used for comparison which does NOT receive the experimental treatment. Experimental group – one variable changed (group that receives the experimental treatment) The outcome must be measurable (quantifiable). Record and analyze data.

Biologists developed a hypothesis regarding mimicry in snakes. If an animal has certain color patterns, then it will not be preyed upon. They tested the hypothesis by making artificial snakes and observing how often they were attacked by predators. Figure 1.20

Figure 1.21 This is an example of a controlled experiment. Such an experiment is designed to compare an experimental group with a control group. Variables Independent Variable adjusted by the experimenter (what you vary) Dependent Variable changes in response to the indep. variable what you measure Constants: variables that remain the same in all groups

Analyze Results You do the experiment using the method you came up with and record the results. Create data tables, graphs to represent data Perform calculations that will determine what results mean (averages, percentages, totals) Identify possible sources of errors Table 1. Percent of total attacks on different colored artificial snakes.

Draw Conclusions You state whether your hypothesis was supported or not and try to explain your results. Table 1. Percent of total attacks on different colored artificial snakes.

Retest In order to verify the results, experiments must be retested.

Communicate Results Share results with science community

Scientific Theories and Laws Hypothesis - testable prediction Theory - explanation of “why”. based on many observations & experimental results Scientific Law - prediction of “what” happens in nature. Theories can explain a law

Practice

Worm Behavior Demo Observations/current knowledge about worm behavior Prediction/Hypothesis: Experiment 400 ml soil 125 ml of water 10 worms Pre-determined #/mass of apple peel Cover with paper. One cold, one room temp

Chapter 1 Section 3 The Nature of Biology

Kinds of Information Quantitative Information Numerical data Can be used to make a graph or a table to communicate data more easily Qualitative Information Data that can be observed but not measured

Measuring in the International System International System of Measurement (SI) Common units: Length = meters Mass = grams Volume = liters Time = seconds Temperature = kelvin and Celsius

Variable: A factor in an experiment. Independent variable: The factor that is different between groups. The topic of interest in an experiment. On graphs, the independent variable always goes on the X-axis. Derby, S. (2004) Graphs and Graphing PowerPoint Presentation. Graphing Review Fig. 1

Dependent variable: The factor being measured in the experiment. Almost always numerical On graphs, the dependent variable is always on the Y-axis. Derby, S. (2004) Graphs and Graphing PowerPoint Presentation. Fig. 1

Types of Graphs Two common types of graphs: – Bar graphs – Line graphs Derby, S. (2004) Graphs and Graphing PowerPoint Presentation. Fig. 2 Fig. 3

Types of Graphs Bar graphs are used when the independent variable has categories. Boys/girls Adults/children Salt water/distilled water /tap water Etc. Derby, S. (2004) Graphs and Graphing PowerPoint Presentation. Fig. 2

Types of Graphs Line graphs are used when the independent variable has numbers. Hours of television watched Age (in years) Calories eaten per day Etc. Both line graphs and bar graphs show the relationship between independent variables and dependent variables. Derby, S. (2004) Graphs and Graphing PowerPoint Presentation. Fig. 3

Derby, S. (2004) Graphs and Graphing PowerPoint Presentation. Making a Graph 1) Choose a scale for each axis that includes all values. Number your gridlines evenly. Fig. 1

Derby, S. (2004) Graphs and Graphing PowerPoint Presentation. Making a Graph 2) Label both axes, including units. Fig. 1

Making a Graph 3) Plot each data point and connect your dots with a line. Derby, S. (2004) Graphs and Graphing PowerPoint Presentation. Fig. 1

Making a Graph 4) Give your graph a descriptive title. Derby, S. (2004) Graphs and Graphing PowerPoint Presentation. Fig. 1