Chemistry
Scientific Method Questions
Name __KEY__________________ Pd.____
8-28-13
1. A student formulated a hypothesis that cotton will grow larger
bolls (pods) if magnesium is added to the soil. The student has
two experimental fields of cotton, one with magnesium and one
without. Which data should be collected to support this
hypothesis?
(a) height of the cotton plants in both fields
(b) diameter of the cotton bolls in both fields
(c) length of the growing season in both fields
(d) color of the cotton bolls in both fields
____B___ Why? The student’s hypothesis said the Mg would
make the cotton bolls grow LARGER, so height, and color as well
as length of the growing season do not relate to the hypothesis.
2. The current knowledge concerning cells is the result of the
investigations and observations of many scientists. The work of
these scientists forms a well-accepted body of knowledge about
cells. This body of knowledge is an example of a
(a) hypothesis
(b) controlled experiment
(c) theory
(d) research plan
_____C__ Why Because a THEORY is a well-accepted idea
based on many experiments performed by many different
researchers.
3. In his theory, Lamarck suggested that organisms will develop
and pass on to offspring variations that they need in order to
survive in a particular environment. In a later theory, Darwin
proposed that changing environmental conditions favor certain
variations that promote the survival of organisms. Which
statement is best illustrated by this information?
(a) Scientific theories that have been changed are the only ones
supported by scientists.
(b) All scientific theories are subject to change and improvement.
(c) Most scientific theories are the outcome of a single
hypothesis.
(d) Scientific theories are not subject to change.
___B___ Why? Theories are always subject to change or
revision as new research data becomes available.
4. A student wanted to test the hypothesis that rooting hormones will
stimulate the production of new roots at a faster rate than would take
place without rooting hormones. Two stem cuttings of equal length,
similar to the one shown below, were taken from a rose, a begonia, and a
geranium plant.
The cut end of one cutting from each plant was dipped into the hormone
and then planted in wet sand. The other cutting from each plant was
planted in wet sand without dipping it into the hormone. All cuttings were
maintained in identical environmental conditions. At the end of 4 weeks,
all the cuttings were removed from the sand and the lengths of the roots
that had developed were measured. The results are summarized in the
data table below.
5. Describe one way the student could make the experiment more valid.
The student should have used MORE THAN ONE SPECIMEN of each
plant variety. One subject is not enough to base results upon.
6. What purpose did the untreated cuttings serve in this experiment?
The untreated cuttings serve as the CONTROL GROUP.
7. Acid rain can have a pH between 1.5 and 5.0. The effect of acid rain on the
environment depends on the pH of the rain and the characteristics of the
environment. It appears that acid rain has a negative effect on plants. The scale
below shows the pH of normal rain.
Provide the information requested below that should be included in a research plan
to test the effect of pH on the early growth of bean plants in the laboratory.
A. State a hypothesis: “Plant growth will be affected when exposed to acid rain.”
“I think plant growth will be affected by acid rain.”
“Plants exposed to acid rain will not grow as well as those
exposed to normal rain”.
B. State a null hypothesis: “Acid rain will have no effect on plant growth.”
C. Identify the independent variable: The acid rain
D. State TWO factors that should be kept constant (there are more than two
possible):
Sunlight, temperature, humidity, soil type, fertilizer, bean variety.
E. How would you construct a data …..
Plant Number
Plant Height, centimeters
Acid Rain
1
2
3
N
Normal Rain
11. Many people who are in favor of alternative medicine claim that large
doses of vitamin C introduced into a vein speed up the healing of surgical
wounds. Describe an experiment to test this hypothesis. Your answer
must include at least:
• the difference between the experimental group of subjects and the
control group
• two conditions that must be kept constant in both groups
• data that should be collected
• an example of experimental results that would support the hypothesis
The experiment would require TWO groups of subjects: The group that
gets the Vitamin C injections would be the EXPERIMENTAL GROUPT
while the group that DOES NOT get the Vitamin C injections would serve
as the CONTROL GROUP in this experiment.
Each groups should contain subjects of similar size, health status, ethnic
group, surgical procedures, diet, medications, (other)…
Wound sizes should be measured at regular intervals, the amount of
Vitamin C injected.
If the group of subjects that received the injections healed more quickly
than those who did not receive the injections, then the data would seem
to support the hypothesis. LARGER trials would need to be conducted in
different locations with subjects of varying, health status, ethnicity, etc.
12. A student recorded the following data table for a six month period. She recorded the amount of
rainfall that fell per week as measured by the school’s rain gauge.
Week
1
2
3
4
5
6
7
8
Rainfall
Amount
0.1 inches
0.3 inches
0.0 inches
0.2 inches
0.0 inches
0.2 inches
0.3 inches
0.0 inches
Week
9
10
11
12
13
14
15
16
Rainfall
Amount
0.1 inches
0.2 inches
0.1 inches
0.5 inches
1.1 inches
0.7 inches
0.6 inches
0.3 inches
Week
Rainfall Amount
17
18
19
20
21
22
23
24
0.1 inches
0.0 inches
0.2 inches
0.2 inches
0.0 inches
0.1 inches
0.3 inches
0.2 inches
Make a graph (your choice of type) to display the data.
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0
1 2 3 4
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
A. From your graph what trends or patterns do you see in the rainfall? Overall the rainfall is fairly
consistent until weeks 12-16 when it increases significantly, then returns to a similar pattern as in
the first weeks.
B. When did the greatest amount of rain fall? Week 13
C. When did the least amount of rain fall? Weeks 3, 5, 8, 18 and 21