Things Needed for Class Covered Shoes Dropbox account with shared folder Noteability/PDF Reader App Charged, updated ipad Textbook Explaineverything App

The Biology website is at /Intro%20Biology/.

The Science of Biology

3 Goals of Science Provide natural explanations for events in the natural world Use these explanations to: Understand patterns in nature Make useful predictions about natural events

What is Science? An organized way of gathering and analyzing evidence about the natural world A way of observing, thinking, and “knowing” about the world A process - not a “thing” A body of knowledge scientists have gathered over many years

Scientific Methodology The common steps that biologists and other scientists use to gather information and answer questions are collectively known as scientific method.

The Steps Making observations and asking questions Making inferences and forming hypotheses Conducting controlled experiments Collecting and analyzing data Drawing conclusions (Stating Sources of Error)

Observation Scientific methodology usually begins with scientists identifying a problem to solve by observing the world around them. Observation: Marsh grass grows to different heights in different locations Question: Why does marsh grass grow different heights in different locations?

Making Inferences Inference is a logical interpretation based on what you know or have observed – a guess at how things work Inferences lead to a hypothesis - a TESTABLE logical explanation for the observations. Hypotheses are SUPPORTED or REJECTED (not proved or disproved)

Formulating a Hypothesis Always use an If… then… statement Inference: something is limiting the growth of the marsh grass - like available nitrogen Hypothesis: IF available nitrogen is related to the growth of marsh grass THEN locations with more nitrogen will grow taller marsh grass

Conducting an Experiment Hypotheses are tested by conducting experiments An experiment is an investigation that collects information under controlled conditions The results of the experiment will either support or refute the hypothesis

Identifying Variables In a controlled experiment only ONE condition is changed at a time. All other variables must be kept the same! The condition in an experiment that is deliberately changed is the independent or manipulated variable. (Nitrogen level) The variable that you observe changing in response to the independent variable is called the dependent or responding variable. (Grass height) Controlled variables = variables that stay the same between control group and experimental group

Controlled Experiment Many experiments involve at least two groups: the control group and the experimental group The experimental group is the test group, in which all conditions are kept the same except for the single condition being tested (the experimental variable - added nitrogen) The control group is the group in which all other conditions are kept the same, but there is no experimental variable (no added nitrogen)

Recording Data Information collected during experiments is called data There are 2 types of data Quantitative Qualitative Quantitative – numerical data like length, mass, temperature and time. Qualitative – verbal data or written observations like color or smell. Data should be organized into tables

Qualitative or Quantitative?

Data Table Table to show Marsh Grass growth in response to added Nitrogen Time (weeks)Control Group Grass Height (cm) Expt Group Grass Height (cm)

Analyzing Results Analysis of results can include graphing data or applying statistical formula. It makes any patterns in the data easy to see

Sources of Error It is important to avoid errors in experimental procedure, data collection and analysis. All measuring tools have limited accuracy Sample size should be large enough to be representative of the general population

Repeating Investigations  After results of an investigation have been published, other scientists can try to verify the results by repeating the procedure  When a hypothesis is supported by data from additional investigations, it is considered valid and is generally accepted by the scientific community

Drawing a Conclusion After careful review of the results a conclusion must be reached Is the hypothesis supported by the data? Is the hypothesis refuted by the data? Is more data needed? Should changes be made to the experiment?

Revisions to Hypothesis During investigations hypotheses often need to be revised and experiments redone several times Python video

Field Studies Sometimes lab experiments are not possible For animal behavior in the wild - Field observations are made – disturbing nature as little as possible For cancer causing chemicals in humans – need to study people who have already been exposed vs. those who haven’t

Scientific Attitudes that help generate New Ideas Curiosity Skepticism Open-mindedness Creativity Scientists share ideas and review each others’ work, which often triggers new questions and ideas

Why is Peer Review important Scientific papers are reviewed by anonymous, independent experts Ensures published work meets the standards of the scientific community Publishing work in scientific journals allows scientists to share ideas and test and evaluate each other’s work. Wikipedia is NOT peer reviewed!!

Developing a Theory  Once scientists have gathered a large body of evidence that supports a hypothesis it becomes a theory - a well tested explanation that unifies a broad range of observations and hypotheses and that enables scientist to make accurate predictions about new situations.  A theory is NOT an absolute truth  A theory can be revised or replaced if new evidence supports a different explanation

Spontaneous Generation Life comes from nonliving material

OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat. HYPOTHESIS: Flies produce maggots. PROCEDURE Controlled Variables (kept the same between exp): jars, type of meat, location, temperature, time Manipulated Variables: gauze covering that keeps flies away from meat Uncovered jarsCovered jars Several days pass Maggots appearNo maggots appear Responding Variable: whether maggots appear CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur. Section 1-2 Figure 1-8 Redi’s Experiment on Spontaneous Generation

Leuwenhoek developed the first simple microscope in the 17 th century and was the first to see microorganisms.

Gravy is boiled.Flask is open. Gravy is teeming with microorganisms. Gravy is boiled. Flask is sealed. Gravy is free of microorganisms. Section 1-2 Figure 1-10 Spallanzani’s Experiment Needham believed that Spallanzani did not disprove spontaneous generation What problem did he point out? Needham showed microorganisms growing from boiled gravy Spallanzani showed sealing the flask prevented growth

Broth is boiled.Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms. Section 1-2 Figure 1-11 Pasteur’s Experiment

Broth is boiled.Broth is free of microorganisms for a year. Curved neck is removed. Broth is teeming with microorganisms. Section 1-2 Figure 1-11 Pasteur’s Experiment In Pastuer’s experiment what was the dependent (responding) variable? What was the independent (manipulated) variable? What variables were controlled? Variables Link to Lab

Studying Life Chapter 1-3

Biology Bios means life and -logy means study of So Biology is the study of living things.

Characteristics of Living Things Biologists have made a list of characteristics that living things share Organisms must have ALL the characteristics to be considered living.

8 Characteristics  Based on a genetic code  Grow and develop  Respond to their environment  Reproduce  Maintain internal balance  Use materials and energy  Made up of cells  Evolve

1.Based on the Universal Genetic Code DNA carry the directions for inheritance Asexual  same as parent Sexual  mix of both parents

2. Grow and Develop Grow = get bigger Develop = change and mature Cells become specialized – have specific jobs

3. Respond to their Environment React to a change in the environment Stimulus = signal Blink in bright sun Flinch if you are hurt Plants roots/shoots respond to gravity

4. Reproduce One of the most obvious of all the characteristics of life is reproduction, the production of offspring. Sexual reproduction Asexual reproduction EX: budding, vegetative reproduction, mitosis

5. Maintain Internal Balance Homeostasis Keep conditions constant Body Temperature control Shiver  warmer Sweat  cooler 98.6 o F or 37 o C

6. Use Materials and Energy Organisms need materials and energy to grow and develop Metabolism = building up or breaking down materials Plants need solar energy We need food

7. Made up of Cells  Cells are the basic unit of life.  Whether an organism is made up of one cell (unicellular) or billions of cells (multicellular), all of its parts function together in an orderly, living system.

8. Evolve As a group organisms change over time

Additional Themes of Biology

Structure and Function Each major group of organisms have their own particular traits that allowed them to evolve in particular ways

Unity and Diversity of Life Although life is diverse, at a basic level they have many things in common. DNA code, carbon based, etc. Share many traits

Interdependence of Nature All organisms depend on each other in the biosphere

Science as a way of Knowing Science helps to explain and predict the natural world so that we can take action. We must understand its strengths and limitations.

Big Ideas in Biology Cellular Basis of Life Information and Heredity Matter and Energy Growth, Development Reproduction Homeostasis Evolution Structure and Function Unity and the Diversity of Life Interdependence of Nature Science as a way of Knowing

A Common Measurement System In science we always use the Metric System or SI (Systeme International) Easy to use multiples of 10 The whole world uses the same units SI Base Units Measurement Unit Symbol Lengthmeterm Mass kilogramkg Timeseconds Electric current ampereA Temperaturekelvin K Amount of substancemolemol Intensity of lightcandelacd

Common Biology Units of Measure Meters and centimeters (length) Celsius (temperature) Grams and kilograms (mass) Milliliters and liters and cm 3 (volume) Seconds and minutes (time)