Chapter 1 The Science of Biology l 1

Chapter 1 The Science of Biology

l 1. 1 What is Science? What is Biology?

What is Science? l Science is an organized way of gathering and analyzing evidence about the natural world. Science is a process.

Biology l The science of life – The study of all living things. – “Bio” = Life – “Logy” = Study of

Scientific Methods l l Scientists use a variety of methods to investigate questions and solve problems. Common steps used to gather information and answer questions are known as Scientific Method.

What is the Scientific Method? l A Process for experimentation that is used to explore observations and answer questions.

Steps of the Scientific Method l l l l l Make Observations Formulate a Testable Question Construct a Hypothesis Test Your Hypothesis by Doing an Experiment and Collecting Data Analyze Your Data and Draw a Conclusion Communicate or Publish. Your Results Formulate a Theory Develop New Hypotheses Revise the Theory

Observations l l The use of one or more of the five senses to perceive objects or events. Recognize the problem and state it clearly.

The Testable Question (Problem) l l l Before you start an experiment you must have a reason to do it. You need to have a question that can be answered through an investigation. This is called a “Testable Question. ”

Examples of the Testable Question l l l Does the amount of sunlight a plant gets affect how it grows? Does caffeine affect reaction time in high school students? Which disinfectant works the best on household germs?

These Are Not Testable Questions l l Is Jerry Rice the best receiver of all time? Is the cafeteria food good? You cannot answer these questions with an experiment. Opinion questions are not testable.

Writing a Hypothesis l l A hypothesis is an “educated guess” about the out come of your experiment. In order to make this guess, you must rely on your background knowledge and the research which you conducted before you began planning the experiment.

A Well Written Hypothesis l l A well written hypothesis is an “if” then” statement. The “if” statement contains information on what your are testing, and the “then” statement reflects your beliefs of the outcome of the experiment.

Examples l l “If a plant is exposed to 12 hours of sunlight then it will grow faster than a plant exposed to 6 hours of sunlight” “If caffeine is increased in someone’s body, then their reaction time will be quicker”

Experimenting l l The process of testing a hypothesis by carrying out procedures in controlled conditions. Experiments should be repeated several times to make sure that the first results weren’t just an accident. .

Controlled Experiment Based on a comparison of a control group with an experimental group. l Controls are variables that never change. l

Variables l l Factors in an experiment that can change. Only one variable in an experiment is changed or manipulated at a time.

Independent Variables l l The manipulated variable. This is the variable that you are testing or changing. Examples: pollutant, water, sun, seeds, etc. Goes on the X axis of a graph and the left side of a table.

Dependent Variables l l l The variable being measured or observed. The responding variable or result of the experiment. Example: growth of plants Goes on the Y axis of a graph or the right side of the data table.

Writing A Procedure l l l A procedure is a list of steps that a scientist takes to complete the experiment. This is a very detailed list that is numbered in 1, 2, 3. . . order. It is not a paragraph! It may include drawings. You know you have written a good procedure when someone can read it and do the experiment exactly like you did.

Conducting The Investigation l l It is now time to start testing your hypothesis! Safety is always an issue here. Be sure to follow all lab safety procedures while conducting the investigation.

Analyzing Data l The process of determining whether data are reliable and whether they support a hypothesis. Statistics, Comparisons

Analyzing Data l Involves placing observations and measurements in some kind of logical order. (graphs, tables, charts)

Recording Data l l All measurements in an investigation need to be recorded in a data table. The table must have a title (related to what you are measuring), and appropriate labels for the rows and columns. Sinking Time For Funnels (seconds) Number Of Washers Trial Number 1 2 3 Avg. 0 110 90 80 93. 3 1 36 31 40 35 2 12 17 17 15 3 12 10 14 12

Graphing Your Data Table l l l In order to understand interpret your data, you need to make a graph. A graph lets you see trends in the data and it also helps you look at the data in a way that is easy to understand. Remember your labels!!

Drawing Conclusions l l l In this step we analyze our data and graphs and decide if our hypothesis was correct or incorrect! We always restate our hypothesis in our conclusion. We discuss any trends we see and we attempt to explain why our hypothesis was correct or incorrect. This is always in paragraph form! Conclusion In conclusion, I can say that my hypothesis (if we add more washers to the funnel, then it will sink faster) was correct. The funnel did sink faster when I added more washers. My graph shows a decrease in sinking time so I have proved that this is true.

Sharing Conclusions l l To make our experiment complete we must share our findings with other people. This can be through discussion or a lab report printed for a scientific journal. Scientists love to read about other’s experiments!

Developing Theories l l After a scientist completes an experiment and has analyzed his/her data they can propose a scientific theory. A theory is an explanation for data based on evidence from experimentation. It explains why things happen.

Law A statement that explains how things happen. Laws are supported by evidence from many experiments and are the only accepted explanation. l Ex. The law of gravity l

Important things to consider when using the scientific method l l l Trials, variables, Controls and Data Tables Trials are repeated experiments, performed in order to make sure that your results are consistent. (the more trials you perform the truer the results. ) Why else would you perform more than just one trial? -Human error, faulty material

Chapter 1 What is Life?

Chapter 1 What is the difference between hypothesis, theory & law? Hypothesis - “an educated guess”; a tentative explanation of phenomena. “If … then” statement. Theory - a widely accepted explanation of natural phenomena; has stood up to thorough & continual testing. Law - a statement of what always occurs under certain conditions.

l 1. 2 Science in Context

Quantitative Information l l l Numerical data Determining the dimensions of an object or other characteristic in precise units. Measured in the International System METRIC MEASEUREMENTS

Measuring in the International System • • An important part of experimentation in science is making accurate measurements understandable to scientists around the world. And the way all of these things are measured all over the world are in Scientific Units or SI Units.

SI Units

Qualitative Information l l Observational data – written descriptions Colors, sizes, behaviors, etc.

SCIENTIFIC SAMPLING l A small sample is used to represent an entire population.

Scientific Equipment l Biologists use many different tools to collect information.

Microscope l An instrument that forms an enlarged image of an object.

Microscope Magnification The power to increase an object’s size. l Total Magnification = eyepiece lens X objective lens Ex: 10 (eyepiece) X 40 (objective) = total mag. (400) l

Compound Light Microscope Most often used by scientist. l A thin specimen must be used so that light could pass through. l

Transmission Electron Microscope l Transmits a beam of electrons through a very thinly sliced specimen.

Scanning Electron Microscope l Scans the surface of an object with a beam of electrons. (produces a 3 D image)

Cell Culture A population of identical cells grown in the lab. l Often used to study bacteria. l

Centrifuge l Separates cell parts by spinning cells at a high rate. (example: blood)

Fractionation Releases the parts of a cell. This process divides the cell into many small parts. l (Acts like a blender) l

Chromatography l l Separation of chemical components of a substance by passing the components in liquid up a piece of filter paper. Example: colors of a leaf, colors of ink

Electrophoresis l l Separates fragments of large molecules (DNA) on the basis of size and charge (+ or -). Example: DNA fingerprinting

Electrophoresis

l 1. 3 Studying Life

Biologists Study the Diversity of Life l l l Living Interactions – how living things interact with other living things, nonliving things, and the environment. Biological Research – the study of observed problems and the proposal of solutions. Research leads to: – Advances in medical treatment, environmental protection, technology, etc.

Characteristics of Living Things

Chapter 1 What are the Characteristics of Life? All living things exhibit five characteristics in combination.

Chapter 1 Five Characteristics of Living Things: 1. Cellular Organization 2. Homeostasis 3. Response to a Stimulus 4. Growth and Development 5. Reproduction

Energy Use and Metabolism • Living things accomplish all characteristics by using energy. • Energy is food. • Metabolism - biochemical reactions that acquire & use energy.

l What are the Characteristics of Life?

1. Cellular Organization • • • All living things are organized by cells. Can be unicellular or multicellular. Each cell contains DNA – genetic material.

Chapter 1 2. Homeostasis The ability of an organism to maintain its internal environment despite conditions in the external environment. • Ex. Human body temperature is controlled by homeostasis. F if body temperature rises, you sweat. F if body temperature lowers, you shiver.

Chapter 1 3. Response to a Stimulus Response to changes in the external environment. • Irritability and adaptation. • Irritability is the immediate response to a stimulus. • Adaptation is an inherited behavior that enables organisms to survive and reproduce. •

Chapter 1 4. Growth and Development • • Life begins as a single cell and grows through cell division to take on the characteristics of its species. Changes that take place during the life of an organism is its development.

Chapter 1 5. Reproduction • • Asexual Reproduction – involves a single parent; progeny are genetically identical to the parent. Sexual Reproduction – involves two parents; progeny are genetically diverse.

l The End