The Characteristics of Life Biology Ms. Haut

Biology Study of life Biologists recognize that all living things share certain characteristics

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

Life at Its Many Levels Biologists explore life at levels ranging from the biosphere to the molecules that make up cells. Figure 1.3

Characteristics of Life 2. Regulation Maintenance of stable internal conditions despite changes in external conditions (Homeostasis) homestudy.ihea.com/wildlifeID/0 43jackrabbit.htm

Characteristics of Life 3. Growth and Development DNA directs pattern of growth and development Pattern of growth characteristic of species

Characteristics of Life 4. Energy Utilization Sum of all chemical reactions carried out in an organism (Metabolism) All energy originates from the sun Plants convert solar energy into sugar Animal use/store energy in own tissues

Characteristics of Life 5. Response to the Environment Organisms have evolved to live and interact with other organisms (Interdependence) Ecology is the study of interactions of living organisms with one another and their environment Food webs Respond to stimuli

Each organism interacts continuously with its environment. Both organism and environment are affected by the interactions. The dynamics of any ecosystem depend on two processes: Cycling of nutrients Flow of energy Figure 1.4

Characteristics of Life 6. Reproduction Process of making more of one’s own kind No organism lives forever; necessary part of living Heredity Passing of traits from parent(s) to offspring Genes are inherited from parent(s)

Characteristics of Life 7. Evolution Change over time New species (group of genetically similar organisms that can produce fertile offspring) can develop over time if enough changes occur Natural selection— survival of the fittest

Figure 1.11

Graphs and Graphing Data Pre-AP Biology Ms. Haut

Variable: A factor in an experiment. – Independent variable: The factor that is different between groups. The topic of interest in an experiment. Has two or more levels. Levels can be numbers (age, weight, etc.) or categories (gender, color, etc.) Derby, S. (2004) Graphs and Graphing PowerPoint Presentation. Experimental Variables

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. Experimental Variables

Variable: A factor in an experiment. 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.

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

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.

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.

Making a Graph 1) Choose a scale for each axis that includes all values. Number your gridlines evenly.

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

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

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

The Scientific Process Pre-AP Biology Ms. Haut

The Process of Science The word science is derived from a Latin verb meaning “to know.” Science is a way of knowing. Science developed from people’s curiosity about themselves and the world around them.

Hypothesis-Driven Science As a formal process of inquiry, the scientific method consists of a series of steps. The key element of the scientific method is hypothesis-driven science.

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

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 A testable statement about your observation Based on research You should be able to give reasons for why you chose your hypothesis If/then… statement

Deductive reasoning is used in testing hypotheses If a hypothesis is supported, and we test it, then we can expect a particular outcome Case study: flashlight failure Figure 1.19

Experiment You figure out a way to test whether the hypothesis is supported. Control group– nothing changed Experimental group – one variable changed 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. Ideally, a control group and an experimental group differ in only one variable.

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

Figure 1.18 ← a tentative answer to some question.

The Culture of Science Scientists build on what has been learned from earlier research. They pay close attention to contemporary scientists working on the same problem. Both cooperation and competition characterize the scientific culture. Scientists check the conclusions of others by attempting to repeat experiments. Figure 1.22

Evolution Connection: Theories in Science What is a scientific theory, and how is it different from a hypothesis? A theory is much broader in scope than a hypothesis. Theories only become widely accepted in science if they are supported by an accumulation of extensive and varied evidence.