Standard 1: The Practice of Science
1. A research group is developing a new design for the turbine blades in a jet engine to increase the engine's thrust. They have
developed four different blade designs. What should the engineers do first in order to test these designs?
A. Use regular-sized versions of all blades for testing in different engines at the same time.
B. Use small scale models of each blade and test them in a small scale version of the engine.
C. Use regular-sized versions of each blade one at a time for testing in the same engine.
D. Use computer software to simulate the behavior of each blade design before creating and testing them.
2. Increasing costs of energy and raw materials have led a chemical company to decide to change its method of production of
one of its pesticides. Therefore, all steps of the process must be evaluated to achieve the highest yield at the lowest cost.
Variables that could possibly be changed include the starting material, reaction temperature, number and duration of
intermediate steps, and disposal of byproducts. How should the engineers approach the production change?
A. They should design a schedule to test changes in several variables at once in order to save time.
B. They should develop a computer simulation of the overall process to test all possible variables together.
C. They should test only one variable at a time to find out how it works best until all variables are optimized.
D. They should create a new design for plant reactors and piping to see how production is affected by these variables.
3. A team of scientists is studying how an acid produced by the body affects an enzyme that catalyzes a chemical reaction. As
part of their study, they add different concentrations of the acid, in moles per liter (M), to test tubes containing both the enzyme
and the reactants of the chemical reaction. In each test tube, the concentrations of the reactants and enzyme are held constant.
Their results are shown in the table. Based on their data, which of these is the best conclusion that can be drawn by the
scientists?
A. The acid enhances the activity of the enzyme.
B. The acid decreases the activity of the enzyme.
C. The acid has no effect on the production of the enzyme.
D. The acid must be present in order for the enzyme to be produced.
4. Miles and Allison are conducting a science experiment on bacteria. Miles and Allison each have a different hypothesis about
what is going to happen. After repeating their experiment several times, they realize that the results of the experiment do not
clearly support either hypothesis. What should Miles and Allison do next?
A. assume Miles' hypothesis is correct
B. revise their hypotheses and do another test
C. change their results to match one of their hypotheses
D. repeat the experiment until it supports one of their hypotheses
5. Erin read about different experiments that were conducted involving lichens. The results showed that lichens can be useful
bioindicators of environmental conditions, since some types are more susceptible to air pollution than others. She wants to
conduct an investigation that will help determine if some areas in her city are exposed to more air pollution than others. What
data should Erin collect in her investigation? Explain how the data could be used to help her reach a conclusion in her
investigation.
A. Erin should select different trees at each of several locations and measure the trees' surface area covered by each type
of lichen. She could find the percentages of each type at each location. An area with a smaller percent of lichens that
are most susceptible to air pollution is probably exposed to more air pollution.
B. Erin should go to several different locations in the city and find out which lichens are present in each area. She would
select one tree at each location and count the number of different lichen types on it. The location that has the greatest
number of different lichen types is probably exposed to the least amount of air pollution.
6. Keyonna is learning about the different hormones that affect plant growth. Auxins and gibberellins are both classes of
hormones that, among other things, affect stem elongation. Keyonna wants to find out how introducing different amounts of each
hormone would affect the growth of plant seedlings. Describe an experimental setup that Keyonna could use that would
demonstrate how each hormone affects plant growth.
A. She should grow 5 different groups of 10 plants. The first group is the control and should not get any auxins. The other
4 groups should receive different amounts of auxins. She should have the same setup for another 50 plants, only this
time using gibberellins. All plants should get the same amount of soil, water and light.
B. She should grow a plant that receives a set amount of auxins and gibberellins. The next plant would receive a different
amount of auxins and gibberellins. She would do this to at least 25 different plants, each receiving a different amount of
each hormone. One plant, which is the control, should get no auxins or gibberellins.
7. Elena lives in a northern city, and during the winter, her parents put salt on their driveway to melt ice. One of the drawbacks is
that salt can damage vehicles. The bottom of Elena's car has some rust and corrosion that she thinks was caused by the salt.
Her cousin's family lives in the same city and also salts their driveway, but Elena's cousin's car appears to be in much better
condition. They bought their cars, which were the same year and in the same condition, at the same time. What is one
hypothesis that could explain the difference in the two cars' appearances? Describe how Elena could test this hypothesis. How
could the results of Elena's investigation be used to answer her question?
A. One hypothesis is that the chemical makeup of the salts they are using on their driveways is different. To test this,
Elena and her cousin should trade cars for a few weeks and see if her cousin's car starts to rust or corrode more. They
should also vary the amounts of salt that they are using to see if that will change the appearance of the cars. If the cars
wind up looking the same after several weeks, Elena can conclude that the salt that her family was using in their
driveway was causing the difference in rust and corrosion.
B. One hypothesis is that the metal in Elena's car is less resistant to rust or corrosion than her cousin's car. To test this,
Elena could get several different samples of metal with the same chemical composition as each car. Next she could
expose the samples of each type of metal to the same amounts of the same type of salts. Each time, she needs to store
the samples at the same temperature and humidity. If one of the metals consistently rusts or corrodes more than the
other, then Elena might conclude that the difference in corrosion was due to the chemical makeup of the metals.
8. Annie and Patrick want to test the claim that listening to classical music while studying improves test performance. Their
friends help them experiment. While they study, half of the subjects listen to classical music, and the other half to rock music.
Everyone is in the same math class, so they will measure their results by comparing the two groups' grades on their next exam.
Part A: What are some ways Annie and Patrick could change their experiment to get more valid results? Part B: What is the
next logical step they should take? Explain why Annie and Patrick should do this once the experiment is complete.
A. Part A: To improve their experimental design, Annie and Patrick should use a much larger group of students. This will
give them more data on which to base a conclusion. They need a control group, such as a group of students who
studies without listening to any music. Before they even begin, they should find out the students' grades beforehand so
that they'll have something with which to compare the grades after studying.
Part B: The next logical step they should take would be having another group repeat their experiment. If other groups
can repeat their experiment and get similar results, this would increase the validity of their experiment.
9 . Part A: To improve their experimental design, Annie and Patrick need more groups of students that listen to more music
types. They should have each person listen to his or her favorite music type during the experiment. This would ensure that each
student is doing the best that he or she possibly can, which would give Annie and Patrick better data.
Part B: The next logical step they should take would be taking the music type that resulted in the highest grades and using it to
develop a study skills program. They should do this to help all students get better grades.
10. Michael wants to test the effect that different concentrations of stomach acid will have on the dissolution of a particular
kind of oral medication. As he sets up and completes his experiment, which of the following experimental designs would
be most likely to help him answer his question?
A. Allow several pills to soak in different amounts of acid of a single concentration and then measure the amount of
dissolution on each.
B. After allowing several pills to be exposed to different acid concentrations, measure the surface area of each that is
dissolved.
C. After allowing a pill to be exposed to one acid concentration, place it in different acid concentrations, and then
measure the surface area that is dissolved
D. Prepare solutions of different acid concentrations, measure 50 milliliters of each into different beakers, and place
different types of pills of the same mass into the beakers.
11. A Magnetic Resonance Imaging (MRI) scanner is a machine used in medicine to display accurate 2-D and 3-D
images of organs inside the human body. It applies strong magnetic fields on the body which are produced by
electromagnets composed of wire coils. The amount of electric current in the wire affects the electromagnet's strength.
Logan has created two electromagnets by tightly wrapping wire around two different nails, each made of a different metal
(Metal A and Metal B), and connecting the wires to D batteries. He hypothesizes that Metal A is a better conductor than
Metal B. He tests his hypothesis by seeing how many paper clips each electromagnet can pick up. His results are shown
below.
Which is the best explanation for Logan's results?
A. Metal A is not a conductor.
B. Metal B is a better conductor
than Metal A.
C. His data are probably incorrect
since they do not support his
hypothesis.
D. His equipment was set up
incorrectly since he got
different results each time.
12. Several groups of researchers were conducting experiments to study how exercise affects cholesterol levels. One
group had college students run two miles a day for six weeks. Another group had senior citizens participate in gentle water
aerobics twice a week for a year. Cholesterol levels dropped slightly among the college students but dropped significantly
among the senior citizens.
Based on these results, what should the researchers plan to do next to validate the findings?
A. Determine that exercise is more useful in lowering cholesterol levels in older people than in young adults.
B. Conclude that moderate exercise is more beneficial at lowering cholesterol levels than more intensive exercise.
C. Design more studies testing the effect of duration and intensity of exercise on cholesterol levels in different age
groups.
D. Repeat the experiment on college students using different groups of students until the results show a drop in
cholesterol levels.
13. Sometimes scientists must make assumptions about their subject of study because some aspect of it cannot be tested
directly. In cases like this, scientists assume that the natural world operates in a consistent fashion.
Which of the following would be the best example of a case in which scientists would have to make an assumption based
on present experience?
A. assuming that modern DNA is composed of the same nucleotide bases that made up DNA 1,000 years ago
B. assuming that rainfall patterns in the northern United States are similar to rainfall patterns there 50 years ago
C. assuming that trees in Brazil use the chlorophyll in their leaves for photosynthesis in the same way trees in Florida do
D. assuming that the feathers on a dinosaur skeleton were used for flight and insulation as they are in modern birds
14. A scientist wanted to find out if the height of a shrub would make it more prone to frost damage. He found a hillside
covered with shrubs and trimmed all the shrubs located at the bottom to one meter tall. He left the shrubs growing at the
top of the hill untrimmed. They ranged from one to three meters tall.
After a heavy frost, he found that 90% of the shorter shrubs had frost damage while only 10% of the tall shrubs did. He
concluded that short shrubs were more likely to suffer frost damage than tall shrubs.
When he submits his research report for review by other scientists, which of the following are they likely to criticize about
his experiment?
A. His hypothesis that shrub height might influence frost damage is not a question worth testing.
B. His conclusion is inaccurate because the location of the shrubs on the hillside might also have contributed to where
frost damage occurred.
C. His methods of recording frost damage must have been biased toward tall shrubs since there was such a large
difference in frost damage.
D. His results are not valid because he had some shrubs in the tall group that were close to the same height as some
shrubs in the short group.