Biology and You

Biology Science – an organized way of gathering and analyzing evidence about the natural world. Examples: Biology – Goals of science: Provide natural explanations for events in the natural world Use explanations to understand patterns in nature and make predictions about natural events.

5 steps of the Scientific Method Observing and asking questions Inferring and forming a hypothesis Designing and carrying out a controlled experiment Collecting and analyzing data Drawing conclusions

Scientific method Observing and asking questions Observation: act of noticing and describing events or processes in a careful, orderly way. Inferring and forming a hypothesis Inference: logical interpretation based on what scientists already know Hypothesis: scientific explanation for a set of observations that can be tested in ways that support it or reject it.

Designing controlled experiments Controlled experiment: one in which only one variable is changed at a time. All other variables are controlled. Ex. Changing the liquid (water, soda and OJ) used to water plants but the amount of sunlight is the same. Control group: exposed to same conditions as experimental groups except for one independent variable.

Variables Independent variable: variable that is deliberately changed Dependent variable: variable that is observed and that changes in response to the independent variable Example on graph on next slide…

3 important things you must have on a graph: Title Labeled axis Units

Collecting and analyzing data Data: information Quantitative: numbers by counting or measuring Qualitative: descriptive Tools used to collect Journals/ computer Graphs and charts Drawing conclusions

Scientific Theory Applies to a well tested explanation that unifies a broad range of observations and hypotheses. Ex. Evolution, cell theory No theory is considered absolute truth – law Theories may be revised or replaced by a more useful explanation

Characteristics of Living Things Are based on a universal genetic code DNA

Living things: Grow and develop Cell division and differentiation

Living things: Respond to their environment Stimulus – signal to which an organism responds

Living things: Reproduce Asexual – single organism produces offspring Sexual – 2 parent cells unite to form new organism

Living Things Maintain a stable internal environment - Homeostasis

Living things: Obtain and use material and energy Metabolism – sum of all chemical reactions

Living things: Are cellular – made up of at least 1 cell Smallest unit of life

Living things: As a group – evolve – change over time