WHAT IS BIOLOGY? & The Scientific Method

Biology Day 2 Pass in signed paperwork Lab reports (Go over expectations) Matter What is Biology? Scientific Method

Biology: The study of anything that was living or is living now. the study of living organisms, divided into many specialized fields that cover their morphology, physiology, anatomy, behavior, origin, and distribution. Living organisms are made up of carbon, nonliving organisms are not made up of carbon. What is Biology

The Experiment Variables: factors that may change in an experiment Independent variable (manipulated by the person running the experiment) Only change one variable at a time: an example could be the amount of fertilizer used on a plant. Dependent variable (Responds to the change in the independent variable). What you measure during the experiment: an example could be How high the plant grows when you add an amount of fertilizer. Controlled Variable: Everything else in an experiment that must be held constant, so they don’t influence the results. An example is the amount of water, amount of sunlight and the type of soil used for each plant, must be the same (constant) The Experiment

Scientific Method is a systematic approach to learning about the world. Observe-an event or process. State the problem and gather background information. Form a Hypothesis-suggested explanation for the event or process. Perform Experiments-test the hypothesis Recorded and analyze the data- Data-recorded observations and measurements Create a table of data and/or graphs Analyze-make calculations and use statistics Draw Conclusions-create a theory to explain your results SCIENTIFIC METHOD

Multiple trials-To ensure accuracy The Experiment Continued Control Setup-Exactly like the experimental setup except it DOES NOT contain the variable of interest. Used for comparison Multiple trials-To ensure accuracy

Hypotheses, Theories, and laws Hypothesis: testable predictions to explain observation EX. If I drop 2 objects with different weights, will they hit the ground at the same time? Scientific Law: a fact of nature that is observed so often it becomes truth. Make predictions about what will happen. EX. The sun will rise every morning in the East But does not explain why something happens Theory: an explanation on many observations and experiments They answer the question “WHY”? EX. Why does the sun rise in the East? (Heliocentric Theory— Copernicus: It has to do with the orbit and rotation of the Earth around the Sun.

SCIENTIFIC MEASUREMENTS Scientists use the SI System of units Mass-kilogram (gram) Length-meter Temperature-kelvin (Celsius) Time-second DERIVED UNITS: consist of a combination of base units volume: l x w x h  liter (liquid) cm3 (solid) Density: mass/volume  g/ml or g/cm3

DENSITY Density = mass/volume Units: g/ml or g/cm3 Why is density important???? It can help to identify an unknown substance You can compare the density to reference tables of known densities

Lab Notes and Report Instruction LAB REPORT OUTLINE

Measurements A number (magnitude) A unit (label) Ex. 25 mg All measurements MUST HAVE: A number (magnitude) A unit (label) Ex. 25 mg Note: Read a graduated cylinder from the BOTTOM of the meniscus! Measurements

Accuracy vs. Precision Accuracy: how close a measurement is to the correct (true) value Precision: how close a series of measurements are to each other (consistent)

GRAPHING Most common type of graph in chemistry  line graph When constructing a graph: Title it. Label axes. * x-axis  indep. Y-axis * y-axis  dep. X-axis Scale axes evenly and show units.

GRAPHING CONTINUED Interpreting relationships from graphs: Direct Proportions – both variables increase or both decrease Indirect Proportions – one variable increases as the other decreases