VARIABLES & HYPOTHESES
The variable that a scientist purposely changes is called this.
Independent Variable
This is the group in an experiment that does not receive the treatment being tested.
Control Group
You spill a few drops of water on a table. The drops stay together instead of spreading into hundreds of tiny drops.
Cohesion
You eat a banana before a race because you want a source of energy your body can access relatively quickly.
Carbohydrate
A student sees a wet sidewalk and says, "It must have rained while I was inside."
Is this an observation or an inference?
Inference
The variable that a scientist measures and records is called this.
Dependent Variable
A student wants to know whether caffeine affects heart rate. She gives different amounts of caffeine to several groups and measures their heart rates.
What is a constant in this experiment?
type of caffeine, amount of exercise, time of day, age range, testing conditions,
A large body of water takes a long time to heat up and cool down. What property of water explains this?
High specific heat
A person's body needs to repair damaged muscle tissue after exercise.
Which macromolecule would be especially important?
Protein
A student measures a pencil and records 15.3 cm.
Is this qualitative or quantitative?
Quantitative
In the statement, "If the amount of exercise increases, then heart rate will increase," what is the independent variable?
amount of exercise
A scientist tests a new energy drink. One group receives the energy drink, while another group receives water. Which group is the experimental group?
The group with the energy drink
A paper towel absorbs spilled water and the water moves through the tiny spaces in the towel.
Adhesion
Which macromolecule is never consumed?
Nucleic Acid
A plant's roots absorb water, and the water moves upward through tiny tubes in the plant.
Which two properties of water work together to help explain this movement?
Cohesion and Adhesion
A scientist predicts that plants receiving more sunlight will grow taller. Identify BOTH variables being investigated.
IV: amount of sunlight; DV: plant growth/height
A scientist wants to know whether different amounts of fertilizer affect plant growth. She uses the same type of plant, same soil, same pots, and same amount of sunlight.
Why is using the same type of plant important?
To ensure only one independent variable is being tested!
A pond reaches freezing temperatures during winter. Ice forms on the surface, but fish survive in the liquid water below.
What characteristic of water makes this possible?
solid water being less dense than liquid water
What is the polymer of a protein?
Polypeptide
A pencil's actual length is 16.5 cm. Five students measure it and record:
How would you describe these measurements?
Accurate, and not precise
You want to test whether the amount of time a student studies affects their biology test score. Write a testable hypothesis.
IF a student studies more, THEN their test score will increase.
IF a student studies less, THEN their test score will decrease.
Variety of answers.
A scientist wants to test whether caffeine affects heart rate.
She gives Group A a caffeinated drink and Group B a non-caffeinated drink. However, Group A exercises for 20 minutes before their heart rates are measured, while Group B sits quietly.
What is wrong with this experimental design, and how could the scientist fix it?
Exercise is another variable that could affect heart rate. Both groups should have the same activity level/conditions before heart rate is measured.
A student adds oil to a cup of water and notices that the two liquids separate.
What TWO things does this tell you about oil and water?
Oil is nonpolar and hydrophobic!
A person hasn't eaten for several hours. Their body has already used available carbohydrates for energy and begins relying more heavily on stored energy.
Which macromolecule is especially important as a long-term energy reserve and what is it's monomer?
Lipid; Fatty Acid
The cell needs quick energy, long-term energy storage, and instructions for building proteins.
Which macromolecule would best match each need?
Carbs (quick energy)
Lipid (long energy)
Instructions (Nucleic Acid)