Science of Biology Notes Photo courtesy of Ms. Furtwangler

What is Science? (1-1) The root ­sci- means “to know”. Science is one way of investigating the world in which we live. Science strives to: explore and understand the natu ral world, explain events in the natural world, and use those explanations to make useful predictions. Are some things unpredictable?

Things that are not science include things like… Art Religion Literature Opinion

Is science better than these things? No! it is simply another way of exploring the world in which we live Science can only concern itself with testable things and\or observable things http://www.ohsu.edu/research/rda/funding/images/scientist.jpg http://www.isleroyalewolf.org/LMV_telemetry_1.JPG

Is scientific knowledge a set truth? In our scientific explanations, we explain how things work using the knowledge we have to explain natural phenomena When our knowledge base changes, our explanation may change

What is Science? (1-1) Scientists use observations (process of gathering information by using your five senses) to gather data. They also use known data to make inferences (a logical interpretation of the data based on past experiences). Practice…

Determine in the picture if it is an observation (O) or an inference (I) _____ There are 2 doors. _____ The people are fighting because someone ate their cookies. _____ One door is closed. _____ They are hitting each other hard. _____ Glass is broken. I O I O

How Scientists Work Scientific Investigations – describe the way scientists gather information and test ideas about nature. The Scientific method describes only one kind of investigation which is called experimental research. Other investigations can be descriptive in nature, like describing newly found species.

Steps to Experimental Scientific Investigation (The Scientific Method): 1. Observe – make an observation of the world around you. There are two kinds of observations: Qualitative observation – descriptive observation Ex: The plant is a dark green. Quantitative observation – a numerical observation. Ex: The flask contains 12.45 ml. There are 4 pennies. Which kind of observation? Let’s practice!

Write 2 Qualitative observations in your class… Write 2 quantitative observations in your class…

Determine if the statement is qualitative (A) or quantitative (B). _____ The sky is blue. _____ There are 4 clouds. _____ There are 3 hills. _____ The first hill is small. _____ The clouds are small. _____ There are a total of 38 birds. B B A A B

2. Ask a question – based on your observation, ask a question you can investigate by gathering information. 3. Research - Look in books, journals and the internet to make additional observations and research about the questions you made from your observation.

4. Formulate a hypothesis: - Propose a scientific explanation to the question being observed and researched. The statement must be testable. (“Which is best?” does not lend itself to being tested). At the end of the investigation, you will either accept or reject your hypothesis.

5. Perform a controlled experiment - Develop and use the experimental design to test your hypothesis. Whenever possible, the hypothesis should be tested by an experiment in which only one variable is changed at a time. All other variables should be kept unchanged, or controlled. Testing fertilizers on plant growth? Keep all other factors constant!

Variables: Factor being tested Controlled- Variables that are kept constant Independent- Variable being manipulated (in a graph found on the x-axis or the horizontal axis) Dependent- Variable that responds (in a graph found on the y-axis or the vertical axis)

1. Independent variable? ___________________ Fly Away Students at DHS wanted to test if paper weight affects the distance paper airplanes fly. The same type of paper airplanes were folded from three different weight papers. The planes were thrown in the mall area to measure the distance they would fly. What are the following variables? Weight of paper 1. Independent variable? ___________________ 2. dependent variable? ____________________ Distance the plane flew

1. Independent variable? ___________________ Lemonade A group of students was asked to compare the taste of lemonade. One glass was from a pitcher made with one cup of sugar. The second glass was made from a pitcher with two cups of sugar. Both pitchers used the same amount of water, lemon juice, and ice. What are the following variables? Amount of sugar 1. Independent variable? ___________________ 2. dependent variable?____________________ Taste

Squidward’s Symphony Squidward loves playing his clarinet and believes it attracts more jellyfish than any other instrument he has played. In order to test his hypothesis, Squidward played a song on 3 instruments for a total of 5 minutes and counted the number of jellyfish he saw in his front yard. He also recorded the number of jellyfish he observed when he was not playing an instrument. 3 trials with no music 1. What is the control group? _____________________________ 2. What is the independent variable? _______________________ 3. What is the dependent variable? ________________________ Instrument Number of jellyfish

A way to remember variables Dependent Responding Y - axis Manipulated Independent X - axis

6. Collect and interpret Data - Collect data (measurements) and perform analysis on the data using graphs and charts

7. Draw conclusions - State whether or not the evidence supports the hypothesis based on your data and analysis. Please notice that we do not prove hypotheses! Proof exists when the chance for error is 0. There is always some chance for error (no matter how small it is) and this existence of chance error means we cannot prove anything in true, honest, science.

8. Report back to the community – Experiments’ results can be used by other to help them with their own experiments. This is what keeps science progressing. http://www.fnal.gov/pub/inquiring/physics/discoveries/images/baryon-talkLR.jpg

What is the difference between a hypothesis, a theory, and a law? A hypothesis is a possible explanation for a set of observations. It has not yet been thoroughly tested.

What is the difference between a hypothesis, a theory, and a law? A theory is a well tested explanation that unifies a broad range of observations. A theory explains observations simply and clearly, and predictions can be made from them. It is widely accepted by the scientific community. Theory of Plate Tectonics

What is the difference between a hypothesis, a theory, and a law? A law is a summary of observed natural events: they are less comprehensive than theories and normally are associated with a mathematical expression. It is also widely accepted by the scientific community. Law of Universal Gravitation

1) They are made up of units called cells. Studying Life 1) They are made up of units called cells.

2) Reproduction (sexually or asexually)

3) Has a universal genetic code (DNA or RNA)

4) Grows and develops

5) Responds to the environment http://www.ciadvertising.org/studies/student/99_spring/theory/eileen/mytheo/passion3.gif

6) Obtains and uses materials and energy

7) homeostasis- maintains a stable internal environment

8) Evolution- Groups change over time http://www.ichthus.info/Evolution/PICS/horse-evol.jpg

Branches of Biology – Biology is studied at many levels of organization from simple to complex: 1) Molecules – groups of atoms Atoms  Molecules 

2) Cell – smallest functional unit of life

3) Groups of cells – tissues, organs, and organ systems http://68.90.81.6/ScienceTAKS/Integration/Cells_files/image022.jpg

4) Organism – individual living system

5) Population – group of organisms of one type that live in the same area

6) Community – populations that live together in a defined area

7) Ecosystem – community and its nonliving surroundings

8) Biosphere – the part of Earth that contains all ecosystems http://oceancolor.gsfc.nasa.gov/SeaWiFS/ICONS/seawifs_biosphere_icon.jpg

Tools and Procedures (1-4) Biologists use metric measurement (the SI system) to gather and interpret data. SI is the universal measurement system.

Tools and Procedures (1-4)

Conversions The metric system is universal measurement system based on the number 10. The meter is the distance value, the gram is the mass value, and the liter is the volume value.

Conversions If you want to change a larger unit into a smaller unit, move the decimal point to the right. If you want to change a smaller unit to a larger unit move the decimal point to the left. Example problems: Convert 100 g to kg. 100.0 g = 0.0074 kL = ________________ L 0.1 kg 7.4

Scientific Notation to make large or small numbers easier to read Numbers that are very small (many numbers after the decimal) have negative exponents Numbers that are very large (many numbers before the decimal) have positive exponents

Scientific Notation The goal is to have a single non-zero number to the left of the decimal (1-9) and the exponent at the end tells you how many decimal places over in which direction you would move to get to the original number. Scientific Notation is really only useful if it will make the number shorter. If the number does not have several zeros in front or behind of the number taking up space, scientific notation will only make the number longer. Keep this in mind when converting.

Scientific Notation Example: 0.0000000001 kg is easier to read as 1.0 x 10-10 kg 1094600000 cm is easier to read as 1.0946 x 109 cm Practice problems: 1980084600000 g = _____________________ 0.00034568 cm = _______________________ 14698 g = _____________________________

Graphing- how a scientists shows patterns in data collected. There are several kinds of graphs; not all of them are useful for data communication. Which type of graph is appropriate for which situations? Line graph - compares two things in which items on one axis affect the items on the other axis. If you are comparing anything to time, it is usually a line graph. (Ex. Amount of CO2 in the atmosphere over the last 6 decades)

Line Graph

Bar graph - compares two or more values. (Ex Bar graph - compares two or more values. (Ex. Number of students with red hair in each class)

Bar Graph

Pie Chart- effective in showing proportions or percentages of a whole thing. (Ex. Comparing the percentage vote that each candidate received in the election)

Pie Chart

Graphing Always draw lines with a ruler, use pencil, and use map pencils when necessary. Make sure your graph contains all components: Title – tell what you are comparing or displaying (be descriptive). X-axis – label and give scale. Y-axis – label and give scale. Key – give meanings of the symbols and colors used on the graph. Data points – clearly marked, and label them if you do not have grid lines.

Microscopes Biologists use microscopes to see living things that are too small for the unaided eye. The two basic categories of microscopes are:

1) Light microscope – produces magnified images by focusing visible light rays. This microscope can be used to magnify up to 1000 times

2) Electron microscope – produce magnified images by focusing beams of electrons. This kind is used to magnify tens and hundreds of thousands of times for extremely small object like a virus. The hair on the leg of a fly (magnified by a factor of 1000) Salt crystals on the antennas of an insect (magnified by a factor of 5000)

Other techniques and tools Cell cultures - in order to study cells under a controlled condition, a biologist can take a single cell and place it in a Petri dish with nutrient solution to help the cell regenerate and fill the whole dish. This cell culture can be used to isolate a single kind of cell, or study interactions between cells and chemicals.

Other techniques and tools 2. Cell fractionation - in order to study a single part of a cell, the cells can be lysed (burst open) and the broken cells can be added to a liquid and placed in a tube. This tube can be placed in a centrifuge which spins the tubes at high speeds which causes cell parts to settle at different levels based on their density, the densest parts will land on the bottom.

Other techniques and tools 3. Autoclave - in order to sterilize tools and kill anything a scientist may have been growing to test, the must kill it with an autoclave. The large steel machine uses heat and pressure to raise the temperature above normal boiling point of water to a temperature in which no bacteria, viruses, or spores can survive.