Biology “The study of life”

Living things are ORGANIZED All made of the same collection of atoms, but we are organized as… molecules proteins, fats, carbohydrates, nucleic acids proteins carbohydrates DNA

Living things are ORGANIZED All made of the same collection of atoms and molecules, but we are organized as… organelles & cells plant cells & animal cells plant cell animal cell

Living things are ORGANIZED All made of the same collection of chemicals, but we are organized as… organs & organ systems respiratory, circulatory, digestive, etc.

Living Creatures Grow and Develop

Even single-celled organisms!

Living creatures REPRODUCE Asexual – 1 parent. Offspring are identical to parent. Sexual – 2 parents. Genes are mixed. Make the next generation

Living creatures use ENERGY Metabolism all the reactions your body performs to make & use energy eating & digestion & elimination of waste synthesis = building Photosynthesis = plants use light energy to build sugars cellular respiration = breaking down sugar (stored chemical energy) into ATP (useable energy)

Living creatures RESPOND Respond to internal changes (stimuli) Homeostasis maintaining balanced conditions inside the body Respond to external changes (stimuli)

Living Things ADAPT change over time. Genetic changes in a population are passed down over generations. Catch food Deter predator Find a mate

Experimentation in Biology The Methods of Science

Methods of Science Using rational thinking and experimentation to answer questions/ solve problems. Note: “Scientific methods” are not a series of steps that must be followed in order. They are guidelines for experimentation to ensure useful, meaningful data.

Methods of Science Question Experimentation begins with a question/problem. Must be testable, falsifiable and measurable. Good example: Will taking drug X reduce the risk of heart attacks in humans? Bad example: Was Albert Einstein the most brilliant scientist who ever lived?

Good Question? A. Will breaking a mirror bring bad luck? B. Are dogs better than cats? C. Do heavy objects fall faster than light objects? D. Will adding fertilizer help plants grow?

Methods of Science Hypothesis Must be specific and explain what you expect to see. Usually and If, then….. Statement. Good example: If dropped from the same height, heavy and light objects will take the same amount of time to fall to the ground.   Bad example: Yes. They will fall the same.

Design a hypothesis… Question: How will a goldfish’s rate of respiration be affected as its water is heated from 50C to 200C? Hypothesis:

Controlled Experiments Developing a Procedure   Controlled experiments compare 2 or more groups. The control group is left alone, under normal conditions. The experimental group is altered, it is subject to your changing variable.   Only one difference exists between the 2 groups, all other factors remain the same. These are called controls.

Controlled Experiments  Independent Variable: The condition that you (the experimenter) are testing. This is the one difference between the control and experimental groups. Example 1: Type of heart attack medicine being taken Example 2: Water temperature for goldfish Dependent Variable: Changes because of the IV. This is usually what you will be measuring, your data. Example 1: Incidence of heart attacks in patients Example 2: Goldfish respiration rate By including only an IV in your experiment (1 difference between groups), you can be sure that any change in the DV is the result of the IV.

Quick Quiz!! Question: Does eating breakfast improve student test scores? Develop a hypothesis for this problem Design a controlled experiment to test your hypothesis What is the IV of your experiment? What is the DV? What variables must you control when running this experiment?

Methods of Science Reporting Your Results Date Tables: Help Organize Data Graphs: Help Interpret Data

Data Tables Column for DV (units) Multiple Trials Column for derived quantity Column for IV (units) 1 2 3 Set up a table: How does length of time dipped in water affect the height the water will travel up a strip of paper towel?

Data Tables 1 2 3 Average height (mm) Time paper towel submerged (sec) Height liquid rose in towel (mm) Trials Average height (mm) Time paper towel submerged (sec) 1 2 3

Showing patterns & trends Graphing Your Data Showing patterns & trends 2008-2009

Types of data (information) Variables what you measure in an experiment dependent variable measured variable unpredictable change: we don’t know how it will change until we do the experiment Y-axis independent variable manipulated variable predictable change: it only changes because we chose how it would change X-axis The effect of _____________ on _____________ INDEPENDENT DEPENDENT 2005-2006

Examples of experiments 1 How does fertilizer affect the growth rate of plants? we set up an experiment testing different amounts of fertilizer on different plants & measuring the growth (height) of the plants: dependent variable (Y-axis)? height of plants independent variable (X-axis)? amount of fertilizer The effect of _____________ on _____________ Amount of Fertilizer Height of Plants 2005-2006

Examples of experiments 2 How does exercise affect heart rate of 10th grade student? we set up an experiment testing different lengths of time of exercise (minutes) on the heart rate of students: dependent variable (Y-axis)? heart rate independent variable (X-axis)? minutes of exercise The effect of _____________ on _____________ Exercise Heart Rate 2005-2006

Examples of experiments 3 What’s the favorite drink of students? we set up an experiment surveying students and asking which is their favorite drink : dependent variable (Y-axis)? number of students independent variable (X-axis)? type of drink The effect of _____________ on _____________ Type of Drink How many students chose it 2005-2006

Making pictures out of data Graphs line graphs graphing data that shows continuous change bar graphs (or histograms) graphing data that is in disconnected groups Which should I use? 2005-2006

Which type of graph? How does temperature affect the rate of cricket chirps? How quickly do sound waves travel through different media? Which brand of paper towel absorbs the most water in a 5-s period? Under which color of light do plants grow most quickly?

Plot Your Graph, Summarize Trends Linear Relationship Exponential Random, no trend

Line of Best Fit