Biology Unit #1 Study Guide
Control Factor
A factor that needs to stay the same. These variables need to be kept constant in each trial. Example: Four fish tanks with different temperatures to measure each heart rate. The control factor: Type of fish, amount of water, diet. Independent var: Temperature of water. Dependent var: Heart Rate (BPM). This would be a line graph.
Control Group
A set of organisms or samples that DO NOT receive the treatment (the independent variable) that is being tested. Scientists can then compare normal changes in organisms or samples with those that may have occurred because of the treatment. The idea of a control group is NOT THE SAME as a controlled factor.
Controlled Experiment
An experiment when only one variable can be changed at a time in order to isolate the results.
Control
Change nothing.
The independent variable is... (What is it sometimes called?)
Changed or manipulated by the experimenter in the design of the experiment. This variable is sometimes called the "manipulated variable".
The dependent variable is what... (What is it sometimes called?)
Changes as a result of the change in the independent variable, if the variable being measured. This variable is sometimes called the "responding variable".
If I drink an energy drink before running the mile, then the time it takes to complete the mile will decrease. What is the dependent and independent variable? What are the variables that need to be held constant?
Dependent Variable: Time Independent Variable: Type of energy drink Constant Variables: Same shoes, same type when drinking energy drink, weather conditions, and same amount of sleep.
Which variable changes in a control experiment?
Independent Variable
Control Experiment Example 4: Is this a control experiment? HAMSTER AND COFFEE BEANS
It is a controlled experiment when the hamster has the exact same species, gender, and age.
What is the independent variable?
It is the variable on the X-axis.
What is the dependent variable?
It is the variable on the Y-axis.
How do you write a research question?
It states the independent and dependent variables. How _______(independent variable)____ affect the _____(dependent variable)_____? Example: "How does the pH of soil affect the number of strawberries produced by a strawberry plant?"
Why is it important for a scientist to use a control group when working with organisms in an experiment?
It's important because it can help compare something that does not receive any treatment, to the ones that do.
Do experiments always have a control?
No. Example: There is no control in the life saver and paper towel lab.
Control Experiment Example 1: Is this a control experiment? LIFE SAVER LAB
Not a controlled experiment because multiple people had different life savers. To make it a CE, the experiment should have been done by one person.
Control Experiment Example 3: Is this a control experiment? TWO PEOPLE IN THE 50 YARD DASH WITH MONSTER ENERGY DRINK (DIFF COLOR)
Not controlled experiment because it wasn't the same person doing the experiment.
Control Experiment Example 2: Is this a control experiment? FIELDS AND FERTILIZER
Not controlled experiment because there isn't one control.
Why is it important to have all variables remain constant except for one? What is this variable called?
So you can make sure the variable results are effective and are making a difference. This variable is called the independent variable.
Scientific Conclusion
States if the data showed and if you should accept or reject your hypothesis. Example: "We set out to test the actual boiling point of water (at sea level) using distilled water; the objective of the experiment was to confirm that is should boil at 100 degrees celsius."
What makes a bar and line graph different?
The numbers on the x-axis.
Which line graphs can you draw a best fit line (multiple choice)? The points scattered across the graph, the points moving downward across the graph, or points moving up and then down (parabola) across the graph?
The scattered graph has no trend (because there is no relationship), the downward graph has a best fit line, and the parabola graph has a best fit line.
In what situation do you make a bar graph?
The words are on the bottom (X-axis/Independent Variable) and the graph is about survey or inventory.
What do bar and line graphs have in common?
They both need to have a title (Y v.s. X).
Control Experiment Example 5: Is this a control experiment? PUNCHING OUT FOUR DIFFERENT CIRCLES OF PAPER AND SOAK EACH IN DIFFERENT BRANDS OF MOUTHWASH
This is not a controlled experiment because the a size of each paper is different.
Example of control group: SCIENTIST IS DOING AN EXPERIMENT TO DETERMINE IF FEEDING RATS A VITAMIN SUPPLEMENT WILL INCREASE THEIR LIFE SPAN. What variables should the scientist control in this experiment (identify 3)? Describe the control group for this experiment.
Variables scientist should control: The same living conditions for each rat, the same amount of vitamin supplement given to each rat, and same ages for each rat/breed. The control group in this experiment is the set of rats that don't receive any vitamin supplement.
Why is information often presented in graphs instead of just lists or tables?
Visual - To see trends fast
What variable always goes on the Y-axis?
What you measure.
In what situation do you make a line graph?
When it is something happening over time or when you're trying to find a relationship between something.
How do you write a graphing title?
Y v.s. X
How do you write a hypothesis?
You write a hypothesis in a "If-Then Form" in a question.