APES Science Practices
All scientific investigations begin with:
(a)
Forming a hypothesis.
(b)
Conducting an experiment.
(c)
Asking a question or observing a
problem.
(d)
Forming a conclusion.
1
Scientific Method
The steps of the scientific method are listed
below, but they are not in the correct order.
What is the correct order of the steps in the scientific
method?
(a)
Conduct the experiment.
(b)
Form a hypothesis.
(c)
Form a conclusion.
(d)
Report your results.
(e)
Make an observation.
(f)
Analyze the data.
2
Answer: e, b, a, f, c, d
Answer: Quantitative data
Scientific Method
Often a scientist collects data that is numerical. For
example, the scientist might measure the length of
growing root tips, or determine the rate of a particular
reaction. What is the name of this type of data?
3
Answer: Qualitative data
Scientific Method
Sometimes a scientist collects data that is descriptive in
nature. For example, “When X and Y are mixed
together, they turn a blue color.” What name is given to
the type of data that is descriptive rather than
numerical?
4
Answer: Graphs, charts, tables, or maps.
Scientific Method
The data collected during an experiment are of little use
unless they are organized. In what ways might data be
logically organized?
5
Answer: The hypothesis is a possible answer to the
question or problem. It is a “testable” statement that
is either supported or unsupported by the data
collected in the experiment.
Scientific Method
Forming a hypothesis is an important step in the
scientific method. What is the purpose of the
hypothesis in an experiment?
6
Answer: Student answers will vary.
One possibility might include: “I predict that the rate
of the enzymatic reaction will be highest at a
temperature of 40 ˚C.”
(This is a statement that can easily be tested.)
Scientific Method
A student is conducting an experiment to test how
temperature might affect the action of a particular
enzyme. How might a hypothesis for this experiment be
stated?
7
Answer: True
Scientific Method
True or False?
Although a hypothesis may be supported by evidence, it
can never be proven true beyond all doubt since new
data might indicate that the hypothesis does not hold
true in all instances.
8
Answer: An experiment is carried out to test
the hypothesis.
Scientific Method
How is it determined if a hypothesis is correct
or incorrect?
9
Answer: In a controlled experiment only one
variable is changed at a time. All other
variables should be unchanged or “controlled.”
Scientific Method
Define the term “controlled experiment.”
10
Answer: Experimental group and control
group.
Scientific Method
Every experiment should consist of two
groups. Name these two groups.
11
Answer: It shows the effect of the one variable
that is being tested.
Scientific Method
In an experiment, what is the purpose of
the experimental group?
12
Answer: The control group is the same as the
experimental group except that the factor
being tested is omitted. The control group
shows what will happen in the absence of the
experimental factor.
Scientific Method
In an experiment, what is the purpose of
the control group?
13
Answer: Independent variable and dependent
variable.
Scientific Method
There are two variables in every
experiment. Name the two variables.
14
Answer: c
Scientific Method
Which one of the following steps would occur last?
(a)
Analyze the data from the experiment.
(b)
Organize the data into charts, tables, and graphs.
(c)
Publish the results.
(d)
Form a conclusion based on the data.
(e)
Repeat the experiment to determine if the data
from the first experiment is reliable.
15
Answer: There are many, many possible answers.
Possibilities include:
Determining the mass, volume, and density of an object.
Measuring the mass of melons fertilized with different
fertilizers.
Calculating the rate of a reaction.
Measuring the amount of oxygen consumed during cellular
respiration.
Determining the change in mass of potatoes placed in
various solutions.
Scientific Method
Give an example of an experiment that uses
quantitative data.
16
Answer: There are many, many possible answers.
Possibilities include:
Describing the behavior of pill bugs placed in a maze.
Observing and describing the parts of a cell being
viewed under a microscope.
Recording color changes during a chemical reaction.
Scientific Method
Give an example of an experiment that uses
qualitative data.
17
Answer: d
Scientific Method
The variable that is deliberately changed in an
experiment is called the:
(a)
Dependent variable
(b)
Controlled variable
(c)
Hypothetical variable
(d)
Independent variable
18
Answer: a
Scientific Method
The variable that is the result of the independent
variable is called the:
(a)
Dependent variable
(b)
Controlled variable
(c)
Hypothetical variable
(d)
Unidentifiable variable
19
Answer: The independent variable is the concentration
of the catalase.
The dependent variable is the amount of oxygen given
off as a result of the reaction.
Scientific Method
Catalase is an enzyme that speeds up the breakdown of
hydrogen peroxide in cells. During this reaction oxygen is given
off. A scientist designs an experiment to determine how much
oxygen is given off when varying concentrations of catalase are
used.
(a)
What is the independent variable?
(b)
What is the dependent variable?
20
Answer: Student answers will vary. One possibility:
“I predict that sucrose will provide the highest rate of
cellular respiration.” Note: The hypothesis must be a
testable statement. The hypothesis may or may not
be supported by the data.
Scientific Method
A student wanted to know which type of sugar would
yield the greatest amount of energy for the cell when metabolized
during cellular respiration by the mitochondria. The student mixed
yeasts in three different sugar solutions: maltose, glucose, and
sucrose. The three sets of yeasts were monitored to determine
which sugar type yielded the most energy. Write a hypothesis for
this experiment.
21
Answer: The yeasts are the organisms carrying out
cellular respiration.
Scientific Method
A student wanted to know which type of sugar would
yield the greatest amount of energy for the cell when metabolized
during cellular respiration by the mitochondria. The student mixed
yeasts in three different sugar solutions: maltose, glucose, and
sucrose. The three sets of yeasts were monitored to determine
which sugar type yielded the most energy. What is the purpose of
the yeasts?
22
Answer: The control could be:
•
Sugar solutions to which no yeasts are added.
•
Adding yeasts to a water solution in which no sugars
have been added.
Scientific Method
A student wanted to know which type of sugar would
yield the greatest amount of energy for the cell when metabolized
during cellular respiration by the mitochondria. The student mixed
yeasts in three different sugar solutions: maltose, glucose, and
sucrose. The three sets of yeasts were monitored to determine
which sugar type yielded the most energy. Describe a possible
control group for this experiment.
23
Answer: The independent variable is the type of sugar
given to the yeasts.
Scientific Method
A student wanted to know which type of sugar would
yield the greatest amount of energy for the cell when metabolized
during cellular respiration by the mitochondria. The student mixed
yeasts in three different sugar solutions: maltose, glucose, and
sucrose. The three sets of yeasts were monitored to determine
which sugar type yielded the most energy. What is the
independent variable in this experiment?
24
Answer: The dependent variable is the amount of
energy obtained from a particular sugar during cellular
respiration.
Scientific Method
A student wanted to know which type of sugar would
yield the greatest amount of energy for the cell when metabolized
during cellular respiration by the mitochondria. The student mixed
yeasts in three different sugar solutions: maltose, glucose, and
sucrose. The three sets of yeasts were monitored to determine
which sugar type yielded the most energy. What is the dependent
variable in this experiment?
25
Possible answers include:
•
The amount of sugar in each solution must be constant.
•
The amount of water in each solution must be constant.
•
Each beaker should receive the same amount of yeast.
•
All beakers should be kept at the same temperature.
•
All beakers should be exposed to the same light levels.
Scientific Method
A properly designed experiment changes only one variable at a time.
A student wanted to know which type of sugar would yield the greatest amount
of energy for the cell when metabolized during cellular respiration by
mitochondria. The student mixed yeasts in three different sugar solutions:
maltose, glucose, and sucrose. The three sets of yeasts were monitored to
determine which sugar type yielded the most energy. List three factors that the
student must keep constant during the experiment.
26
Answer: The experimental groups would consist of
organisms that are given varying amounts of caffeine.
Scientific Method
A student wants to test the effect of different amounts
of caffeine on the heart rate of Daphnia, a small
crustacean. Describe the experimental groups in this
experiment.
27
Answer: The control group would consist of Daphnia
that are exposed to all of the same conditions as the
experimental groups, but they would receive no
caffeine.
Scientific Method
A student wants to test the effect of different amounts
of caffeine on the heart rate of Daphnia, a small
crustacean. Describe the control group in this
experiment.
28
Answer: The independent variable is the quantity of
caffeine given to Daphnia.
Scientific Method
A student wants to test the effect of different amounts
of caffeine on the heart rate of Daphnia, a small
crustacean. What is the independent variable?
29
Answer: The dependent variable is the
recorded heart rate of Daphnia.
Scientific Method
A student wants to test the effect of different amounts
of caffeine on the heart rate of Daphnia, a small
crustacean. What is the dependent variable?
30
Answer: The independent variable is the different wavelengths
of light.
The dependent variable is the amount of glucose produced at
each wavelength of light.
Scientific Method
Consider an experiment designed to determine glucose production
during photosynthesis when leaves are exposed to different
wavelengths of light.
(a)
What is the independent variable?
(b)
What is the dependent variable?
31
Answer:
Experiments are repeated to see if
the same results are obtained each time. This
gives validity to the test results.
Scientific Method
Why must an experiment be repeated
many times?
32
Answer: If more than one variable is changed at a
time, it cannot be determined which variable is
responsible for the observed results.
Scientific Method
Why is it necessary that only one variable be changed
in an experiment, and that all other variables remain
constant?
33
Answer: The rate of photosynthesis is greatest during the months
of May, June, and July. The rate of photosynthesis is significantly
less during the winter months.
Scientific Method
Examine the data shown in the graph below.
What conclusion can be reached by the data shown on the graph?
34
Answer:
(a)
The temperature of the water.
(b) The breathing rate of the fish.
Scientific Method
Study the information in the table.
(a)
What is the independent variable?
(b)
What is the dependent variable?
35
Answer: Each species of fish has an optimum temperature that provides for
the best breathing rate. The breathing rate of fish increases leading up to
their optimum temperature and decreases at temperatures higher than
their optimum temperature.
Scientific Method
Study the information in the table.
What conclusion can be reached from this data?
36
Answer:
(a)
23 ˚C
(b)
At 20 ˚C, the breathing rate of the catfish is much higher
than the breathing rate of the bass.
Scientific Method
Study the information in the table.
(a)
At what temperature will the breathing rate of the bass be the highest?
(b)
At 20 ˚C, how does the breathing rate of the bass compare to the
breathing rate of the catfish?
37
Answer: The boiling point of water is determined
without the addition of any type of solute.
Scientific Method
An experiment is carried out to determine if the boiling
point of distilled water is affected by the addition of
different types of solutes. Describe a control group for
this experiment.
38
Answer: Student answers will vary. The hypothesis should be
a testable statement using the variables given in the
experiment. For example: I predict that the volume of each
gas will increase as the temperature increases.
Scientific Method
A scientist is designing an experiment to see how
temperature changes affect the volumes of three
different gases. Write a hypothesis for this experiment.
39
Answer: The independent variable is the change in
temperatures at which each gas will be measured.
Scientific Method
A scientist is designing an experiment to see how
temperature changes affect the volumes of three
different gases. What is the independent variable?
40
Answer: The dependent variable is the change in
volume of each gas.
Scientific Method
A scientist is designing an experiment to see how
temperature changes affect the volumes of three
different gases. What is the dependent variable?
41
Scientific Method
42
At what temperature does
Gas A have a volume of 50 L?
Answer:
Approximately 16 °C.
Answer:
Approximately 28 L.
Scientific Method
At 50 °C, what is the
volume of Gas B?
43
Answer:
Approximately 4 L.
Scientific Method
Predict the volume of Gas
C if the temperature is
lowered to –200 °C.
44
Answer:
Approximately 331 °C
Scientific Method
At what temperature will
Gas B have a volume of
53 L?
45