Biology I Unit I Notes to Study for Test

Lab Equipment, Procedures and Safety Symbols

Use a graduated cylinder to accurately measure liquids in milliliters (ml).  You always want to choose the graduated cylinder that holds the smallest amount possible while not being smaller than the amount you are measuring-this allows it to be the most accurate.  When measuring, we look at the bottom of the curve in the surface of the liquid (the meniscus).  Beakers and Erlenmeyer flasks can be used for storage and mixing, but are not as precise.

Use a triple-beam balance to measure mass in grams (g). 

Use a meter stick to measure length in meters (m) or centimeters (cm). 

Use a thermometer to measure temperature in degrees Celsius (°C).

Use a spring scale to measure force in Newtons (N).

Microscopes allow us to see object that are much smaller than we can see with our eyes.  When carrying a microscope, carry it with one hand on the base and the other on the arm of the microscope.  To find the magnification, multiple the magnification of the first lens by the magnification of the second lens. 

Light Microscope	Electron Microscope
Can view living things	Specimens must be dead
Can see color and movement	Black and white, no movement
Not very good magnification	Really good magnification
Easy to use, not expensive	Hard to use, really expensive

Bunsen burners are used to heat up objects in the lab.  When using a Bunsen burner, make sure that you keep your hair and cloths tied back so they don’t start on fire.  When heating a substance in a test tube, make sure you don’t fill it all the way to the top and you point the top of the test tube away from you so chemicals don’t splatter onto you.  Also make sure nothing flammable is around the flame.

The eye wash station is available to clean out your eyes if chemicals get into them.  The safety shower is available if you get chemicals on your skin or clothing.  Make sure that you wear safely goggles when working with chemicals to protect your eyes. 

·         If you break glass, there is a special container for broken glass-make sure you sweep it up and don’t touch it with your hands-the edges are sharp and can cut you. 

·         If a fire breaks out, use the fire extinguisher and PASS (Pull the pin, Aim the nozzle, Squeeze the handles and Sweep the nozzle side to side).

·         If you need to dispose of living tissues, use the biohazard container.

·         If you ever find something that you can’t identify, spill something, break something, or hurt yourself in any way, let the teacher know!

Safety Symbols:

 Radiation

Biohazard

Poisonous/Toxic

 Flammable

Corrosive

 No food or drink

Hypothesis and Scientific Method

A hypothesis is an educated prediction of what we think will happen.  Hypotheses are often written as an If…then…. statement.  If..then…statements always make a prediction about what will happen if we change something.  The most important thing to remember is that a hypothesis needs to be something I can test.  Saying rap music is better than pop music is not a hypothesis because we cannot test that.  Saying more people prefer rap music in this room than country music is a hypothesis because we can test that by taking a poll.

The scientific method is a systematic way to figure out the answer to a problem.

1. Make an observation or ask a question
2. Gather information
3. Create a hypothesis: an educated prediction of what is going to happen
4. Design and conduct an experiment
5. Analyze the data
6. Draw a conclusion

If the data supports our hypothesis, then we can keep it and perform another experiment to see if it still holds true.  If the data does not support our hypothesis, then we will reject the hypothesis.  If many experiments support our hypothesis, then we call it a theory.  Theories have support from many different experiments and many trials of each of those experiments.  If something in science seems to always be true, we call it a law.

Experiments

Experiments are how scientists determine relationships in the world around them. 

Independent Variable:  The variable that we change or vary to see what happens. If our hypothesis was an if…then… statement, the IV would be the if. 

Dependent variable:  The variable we measure to see what change has taken place.  This will be the then of our if..then…statement. 

Constant:  Something that does not change or remains the same.  Everything in an experiment other than the independent variable should be constant.

Control is the group you are going to compare everything to.  It is the group where you don’t change anything-it is the normal state of the IV. 

Replicability:  Doing an experiment multiple times to make sure that you get the same results over and over

Common pitfalls of experiment designs:

·         Forgetting to have a control.  A control is needed in order to tell if a change has taken place.  If you don’t have a control, you don’t know if changing the IV has caused a change in the DV (you have nothing to compare the experimental group to!).

·         Having more than one IV.  If we manipulate more than one thing, it is impossible to know which manipulation caused the differences we see in the DV.  This is why you only have one IV and everything else is kept constant.

·         Not replicating the experiment.  If you only do it once, you cannot tell if that is the result you will always get.  Replicability allows you to prove that this will always happen. Part of replicability is having a large sample size when we do experiments-if your sample is small, it is difficult to conclude that something happens all the time.

Graphs

Parts of a graph:

Title-goes across the top.  Tells you what the graph is about. Usually is written to explain the variables you are comparing.

Axes labels or legend- gives you information on what they represent and how they are measured.

X-axis:  the horizontal one (side-to-side).  Always has the independent variable.

Y-axis: the vertical one (up and down).  Always has the dependent variable.

Types of graphs:

Bar Graph: Used to compare data between groups.

Line Graph:  Used to compare data for an independent variable that is continuous (can get larger and smaller like time or temperature)

Pie Chart:  Used to show parts of a whole.  The information is given as percentages.

Creating Scales:

When you are deciding what value to make each division along an axes, you need to take the largest value you have for each axes and then divide that value by the number of divisions you have on that axes.  You will then round up to the nearest value that makes sense for the graphs (nearest whole number, nearest multiple of 5, 10, 100, ect.)