The Science of Biology Chapter 1

What is Science?  Science is an organized way of gathering and analyzing evidence about the natural world. No supernatural phenomena No supernatural phenomena A way of knowing based on A way of knowing based on evidence evidence Explanations are based on Explanations are based on evidence not belief evidence not belief

 Science helps us understand what we know, but much of nature still remains a mystery.  Science also helps us understand what we don’t know. Uncertainty is part of the scientific process.

The Scientific Method…General Steps in Science  Scientist John Heart wanted to discover why salamanders were disappearing from the Ponds of the Rocky Mountains in Colorado

Scientific Method Stages  1. Collecting Observations Observation is the act of noticing events in an orderly way Observation is the act of noticing events in an orderly way Heart learned what they eat, conditions they thrive in, behavior, when they reproduce. Heart learned what they eat, conditions they thrive in, behavior, when they reproduce.

 2. Asking Questions Observations often lead to questions Observations often lead to questions Why were the number of salamanders dropping? Why were the number of salamanders dropping? Was acid precipitation part of this cause? Was acid precipitation part of this cause?

 3. Forming a Hypothesis An educated guess that might be true based on what is already known An educated guess that might be true based on what is already known Must be testable Must be testable Melting acidic snow was making the ponds acidic and harming the salamander embryos Melting acidic snow was making the ponds acidic and harming the salamander embryos

 4. Experiment Design the experiment based on observations, literature search and the hypothesis Design the experiment based on observations, literature search and the hypothesis Heart tested whether exposure to pH levels would harm the salamanders that hatched. Heart tested whether exposure to pH levels would harm the salamanders that hatched. Control group: a group in the experiment that receives no experimental treatment Control group: a group in the experiment that receives no experimental treatment Salamanders that would hatch under normal water conditions Salamanders that would hatch under normal water conditions

 5. Analyze Results and Draw Conclusions Look at the experimental data and try to figure out what it means. Look at the experimental data and try to figure out what it means. Graphing the results and doing statistical analysis will help one analyze the data. Graphing the results and doing statistical analysis will help one analyze the data. Heart found that his data supported his hypothesis and that acidic water did in fact lower the number of salamanders that hatched from eggsHeart found that his data supported his hypothesis and that acidic water did in fact lower the number of salamanders that hatched from eggs

 6. Revise Hypothesis Determine if your original hypothesis was correct or needs revision and further experimentation Determine if your original hypothesis was correct or needs revision and further experimentation

 Independent variable: variable that YOU change in the experiment. X-axis.  Dependent variable: the variable that you are measuring, your data. Y-axis It is important to control variables because if several variables are changed in the experiment, researchers can’t easily tell which variable is responsible for any results they observe.

Identify the independent and dependent variable.  To what extent can cigarette smoke cause lung cancer?

Law vs. Theory  Laws: Events that always occur in nature The Law of Gravity The Law of Gravity  Theory- well tested explanations of why things occur in nature. Major hypothesis that have never been proven wrong  Theories are the guiding principles of science  Ex: The cell theory  Ex: The theory of evolution

Graphs  A Line Graph – When data is continuous;  X-axis is the independent variable  Y-axis is the dependent variable

 Bar Graphs – When the information is not continuous or related;  Used when  Graphing 2 independent variables.  Bar graphs are useful to show comparisons when the two variables are not related.  The bar graph is used for taking counts or surveys.

 Pie Graphs – Used when dealing with percent values out of a 100%.  Specific % values are needed

Sample Combination Chart: Bar and Line Graph

Our Example Experiment  How does the gender of an individual affect the amount of vital lung capacity?  What are your hypotheses?  We will use a spirometer to test your hypotheses.  What are the constant conditions? Control? Independent & dependent Variables? Results? Analysis?

 Scientific Method Practice Sheet

 In the fall as you notice it getting colder, you observe all the leaves on the trees around Lower Moreland changing color. You hypothesize that the temperature change could be causing the leaves to change color. You decide to set up an experiment to test this.  What is your independent variable?  What is your dependent variable?

Studying Life  What does it mean to be alive?  What distinguishes living things from nonliving matter? Bio- ology life the study of

 What are some characteristics of life? Cellular organization Cellular organization Reproduction Reproduction Homeostasis Homeostasis Heredity Heredity Responsiveness Responsiveness Growth and development Growth and development Evolution Evolution Metabolism Metabolism An organism displays all the characteristics of life

1. Cellular Organization  All living things are made up of cells  The cell is the smallest unit capable of life functions  Cells are complex and highly organized  : organisms made up of one cell  Unicellular organisms: organisms made up of one cell  : organisms made up of more than one cell  Multicellular organisms: organisms made up of more than one cell

2. Reproduction  Necessary for the survival of a species  Species: organisms that can interbreed and can produce fertile offspring.  Asexual reproduction- reproduction that does not involve the union of gametes or sex cells. The offspring is a clone of the parent  Sexual reproduction- reproduction that involves the union of gametes, offspring looks unique

3. Homeostasis   The ability for organisms to keep their internal conditions stable  How do humans maintain homeostasis? Sweating Sweating Shivering Shivering Wearing clothing Wearing clothing Physically active Physically active

4. Heredity  Living things are based on a universal genetic code….DNA!  With a few minor variations, life’s genetic code is almost identical in every organism on earth  Mutation: a change in the genetic material of a cell the genetic material of a cell

5. Responsiveness  Living organisms respond to external stimuli.  A stimulus is a signal to which an organism responds

6. Growth and Development  Growth – an increase of the organism’s mass  Development – Change of structure for an organism to become an adult. Egg Larva Pupa Adult  Differentiation: the process in which cells become specialized to do different functions

 As a group, groups of organisms change over time  Evidence of this is found in fossils  Those organisms with genetic traits that better enable them to meet natures challenges survive and reproduce in greater numbers 7. Evolution

8. Metabolism  The sum of all chemical reactions happening in an organism.  Living things obtain and use material and energy  Where do we obtain our energy from?  Where do plants obtain their energy from?

 See how many characteristics of life and new vocab words you can use as we look at some videos  ion/gallery.php?Category=Zebrafish&Secti on=Introduction ion/gallery.php?Category=Zebrafish&Secti on=Introduction ion/gallery.php?Category=Zebrafish&Secti on=Introduction

Themes of biology- Big ideas  Cellular basis of life  Information and heredity  Matter and energy  Growth, development and reproduction  Homeostasis  Evolution  Structure and function  Unity and diversity of life  Interdependence of organisms  Science as a way of knowing

 With partners complete the biology theme worksheet.

What do biologists do?  What are some of the jobs done by biologists?

1. Study the diversity of life

2. Research diseases

3.Develop technologies technologies DNA Sequencing Machine

4. Improve Agriculture  Biologists can transfer genes from one kind of plant to another and this changes hereditary information in its cells. This is called genetic engineering. This is called genetic engineering.

5. Study and preserve the environment

Scientific Measurement  Scientists use the metric system when collecting data and performing experiments Units are based on multiples of 10 Units are based on multiples of 10 Revised version of original metric system is SI (International system of units) Revised version of original metric system is SI (International system of units) What is the advantage of using a common system? What is the advantage of using a common system?

Measurements of Length  1. Kilometer – 1,000 meters  2. Dekameter – 10 meters  3. Meter - 1  4. Decimeter – 0.1 meter  5. Centimeter – 0.01meter  6. Millimeter – meter  7. Micro(micrometer)– meter, 1 millionth  8. Nanometer –10 -9 meter, 1 billionth  9. Angstrom – meter, 1 ten billionth

Electron Microscope Light Microscope Human Eye

Diameter Of DNA Diameter Of a ribosome

Practice  1 kilometer = __________ meters .45 nanometers = __________ meters  5000 milligrams = _________ grams  130 meters = _________ kilometers  2500 milliliters = _________ liters .017 grams = __________ milligrams  micrometers = _______ angstroms  50 decimeters = ________ dekameters