Objective 1.1 What is Biology?
Objective 1.2 Is it living or nonliving?
What is Biology???
Biology is the study of life.
If something is living, it must be able to do 7 things. We call these 7 things, the unifying themes of biology.
7 Unifying Themes of Biology
• Cellular structure and function
o All living things are made up of one or more cells
o These cells grow and develop
o The cell is the smallest unit capable of all life functions
o Some bacteria only have one cell, but you have more than 100 trillion cells!
• Reproduction
o All living things can reproduce and GROW
o It’s the process when organisms make more of their own kind from one generation to the next.
• Example: When parents have children
• Metabolism
o We use the energy we get from food to grow, move, and process information. Plants get their energy from the sun.
o Metabolism is sum of all the chemical reactions carried out by an organism
• Homeostasis
o Hoh-mee-oh-STAY-sis
o The inside environment STAYs the same! Even with changes in the external environment.
o Example: Your body temperature is always 98.6 degrees F, in both the winter and summer.
• Heredity
o Passing of traits to their offspring.
o That’s why children tend to look like their parents.
• Evolution
o Change in the inherited characteristics of species over generations
o It happens slowly over a long period of time.
o Interdependence
• Interdependence
o Organisms live and interact with other organisms and the environment
o Ecology: studies the interactions of organisms with one another and with the nonliving part of their environment
o You are an organism!
o What are some things that you interact with?
o It is living or nonliving?
If something is non-living, it may do SOME of the 7 themes listed above but not all.
For example, cars convert the energy in gasoline so that it can move. This kind of sounds like metabolism. HOWEVER, cars cannot reproduce. Cars don’t have cells, etc etc.
Some is also non-living, if it used to be alive, but isn’t anymore.
Example, a dead flower. It definitely used to be alive, but now it can’t grow (cellular reproduction), use the sun’s energy to make food (metabolism), make baby plants that look similar to it (heredity) etc.
Let’s practice! Tell me if the objects below are living or nonliving and explain why!
A squirrel
Fire
Water
Carrots growing in garden
Carrots at the supermarket
Objective 1.3: The Scientific Method
What is the scientific method?
• The Scientific Method is the process that scientists use to identify and answer questions about the physical world.
• We will be using the Scientific Method throughout the year to answer scientific questions using evidence and experiments.
There are 6 steps of the scientific method. They are:
1. Ask a question.
• Your research question should be based on observations/evidence.
• You observe that the gas station has 3 different types of gas (premium, plus, regular).
• Question: Does the type of gas affect how quickly a car goes?
2. Construct a testable hypothesis
• A hypothesis is an educated guess
about the answer to your question.
• A hypothesis is testable if you can do an experiement to prove whether it is true or false.
If you use the higher level of gas, then your car will go faster.
3. Test hypothesis with an experiment
• Your experiment should allow you to determine whether your hypothesis is true or false.
• Get 3 of the same car.
• Give one regular gas
• Give the other plus gas.
• Give the last premium gas.
4. Collect and analyze data
• Data is evidence/information we collect during an experiment often including numbers and measurements.
• It is important to collect data because we can use it to support or reject our hypothesis.
• Time how long it takes for each car to travel 1 mile.
• Graph your data in a graph of time vs. type of gas.
5. Draw conclusions and report results
• Your conclusion should be an answer to your hypothesis that is based on your data.
• You will report the results of your experiment by writing them up in a formal lab report that describes what you did at each step of the Scientific Method.
• My hypothesis is correct. The car that had premium gas traveled 1 mile the fastest. The next fastest was the car with plus gas. The car that has the regular gas had the slowest time.
6. Ask further questions, then retest!
• What other questions did your experiment make you think of? What else do you want to know?
• Ask a new question and start back at step 1 of the scientific method!
• You will usually also want to do the same experiment more than once. This is called conducting multiple trials Does the quality of gas affect how fast motorcycles go?
Objective 1.4 Variables and Controls
What is a Controlled Experiment?
• An experiment is controlled if only one thing that can affect the outcome of the experiment is changing.
• The things that are NOT changing are the controls. They stay the same.
• You may also have a control group. The control group is the part of the experiment where nothing is being changed.
So what’s changing?
• The things that are changing during the experiment are called variables. (Variables vary) These changes allow you to test your hypothesis
• There are two types of variables:
o 1. Independent variable A factor that is manipulated/changed by the experimenter during the experiment.
• Shown on the x-axis (horizontal) of a graph
2. Dependent variable A factor that is measured to determine if the independent variable has any effect; It is being influenced by the independent variable. The dependent variable depends on the independent variable.
• Shown on the y-axis (vertical) of a graph
Example A
• You are doing an experiment to determine if the amount of sugar you put in water changes the boiling point of the water.
• The independent variable is what you are changing.
o Independent variable = Amount of baking soda
• The dependent variable is the factor that is being influenced by the independent variable.
o Dependent variable = height of the cake
• The controls are what you are keeping constant. They are not changing.
o Controls: amount of water, sugar, flour, eggs, temperature
o Control group: cake without baking soda in it
So why is it important for your experiment to be controlled?
• If you change more than one thing at a time, you don’t know exactly what variable is causing the dependent variable to change.
Consider the cake experiment. What if you add more baking soda AND change the temperature? The height of the cake might change, but is it because there’s more baking soda or because the temperature is higher?
So why is it important for your experiment to be controlled?
• You want to stop your door from squeaking. You oil the hinges, sand the doorframe and change the doorknob. It works.
• What caused the doorframe to stop squeaking? Was it the oil? Sanding? The new doorknob?
o We don’t know. Maybe it was a mix of all three!
• If our experiment had been controlled, we would have tried only one thing at a time. Then we would know which method actually caused the door to stop squeaking.
• It is important to have a controlled experiment so that you can determine the effects of a single variable (the independent variable) on the dependent variable.
• This will allow you to prove or disprove your hypothesis.
Example B
I have two fish, Hannah and Montana. They are both Angel Fish. I want to see if how much I feed them determines how fat they get. I feed Hannah one pinch of fish food a day, and I feed Montana 4 pinches of fish food a day. After two weeks, Hannah gained 1 gram and Montana gained 3 grams.
What are the controls in my experiment? ____________________________________________________
What is the independent variable? _________________________________________________________
What is the dependent variable? ___________________________________________________________
Example C
My twins are in the same science class. Julia studies 1 hour every night and Juliana studies 2 hours every night. They both do all of their homework and have perfect attendance. They take their first science test. Julia gets a 80% and Juliana gets a 89%.
What are the controls in my experiment? ____________________________________________________
What is the independent variable? _________________________________________________________
What is the dependent variable? ____________________________________________________________