Instructions for teachers:
The ACT Science practice allows the students and teacher to break down the figures, examine more
carefully what the variables are in each graph, what is being studied, and how everything is measured.
The document is 3 pages (one page for each day of ACT week). You can photocopy the first 2 pages of
the document front-to-back and have students keep this paper for the entire week.
The last page can be read out loud, projected on an LCD or an overhead projector, or photocopied.
However, it should not be handed out to students until the final day, as many students want to rush into
the multiple choice questions.
It is more important that some discussion takes place about the experiments rather than rushing through
the answers to the questions.
Any feedback on Science ACT practice is appreciated to the science team. Send e-mails to Victor Chen.
DAY 1 – SCIENCE ACT
In the ACT Science Section, you will see three
“Experiments” passages. They are easy to spot. They
usually contain an introductory paragraph followed by
a number of experiments and six questions.
1. The first thing you need to do
in an Experiments passage is to
identify the objective. The
objective is a statement that tells
you the purpose of the study
(what they are studying). The
objective is usually found in the
beginning or the end of the
introductory paragraph. Once
you find it, underline the
objective.
2. The second thing you need to
do is to follow the procedure of
each experiment and identify the
variables. Then, jot down a few
words along side each of the
experiments to make a note of
what is changing in each case.
Space is given to you here so you
can write down your notes.
3. The final thing you need to do
in an Experiments section is to
study the results. The results are
the conclusion of the study.
When you study the results, make
sure you underline them or write
some notes in the margin. Once
you’ve finished this step, look for
any patterns, and move on to the
questions.
DAY 2 – SCIENCE ACT
Try to answer the following open-ended questions
about the passage. Use your notes from the previous
page to guide your thinking.
1. According to Table 1, what might best contribute to
the growth of E. coli bacteria?
2. According to the results of the 3 experiments, how
is reproduction in E. coli bacteria different from other
types of bacteria?
3. What conclusions can you draw based solely on the
results of Experiment 1?
4. Bacteria will often reproduce until all of the
nutrients have been depleted. How do you think the
experiments could be altered to maximize the length of
time that bacteria will reproduce?
5. Based on the data from Experiment 2, what
conclusions can you draw?
DAY 3 – SCIENCE ACT
Answer the following multiple choice questions using
what you have learned about the Experiments passage.
1 According to Table 1, what might best contribute to the growth of
E. coli bacteria?
A. A pH level above 8
B. A pH level below 6
C. A pH level near 7
D. A pH level above 7
2. According to the results of the 3 experiments, E. coli bacteria is
different from most bacteria in that:
F. it does not require growth factors to reproduce.
G. it does not reproduce if a light source is present.
H. it does not reproduce if amino acids are not available.
J. it requires a specific nutrient concentration to reproduce.
3. Which of the following conclusions is strengthened by the results
of Experiment 1?
A. E. coli bacteria reproduce most efficiently at a pH level of 7.
B. E. coli bacteria cannot reproduce at a pH level below 8.
C. E. coli bacteria cannot reproduce at a pH level above 6.
D. E. coli bacteria can only reproduce if the pH level is near 7.
4. Bacteria will often reproduce until all of the nutrients available
have been depleted. How could the experiment be altered to
maximize the length of time that bacteria will reproduce?
F. Change the observation time from 6 hours to 12 hours.
G. Regularly resupply each group of bacteria with unlimited
nutrients.
H. Increase the rate of growth by decreasing the pH levels.
J. Do not test the effect of different nutrient combinations on
growth.
5. Which of the following statements is most likely true based on
the results of Experiment 2?
A. Lower levels of nutrient concentrations result in a higher
growth percentage of E. coli.
B. Higher levels of nutrient concentrations result in a lower
growth percentage of E. coli.
C. Higher levels of nutrient concentrations result in a higher
growth percentage of E. coli.
D. Nutrient concentration has no effect on the growth percentage
of E. coli.
6. The experiments recorded the percentage growth that occurred
after a 6-hour period. Bacteria often reproduce at a rate that
drastically varies from one stage to the next. The best way to
study the different stages of growth would be to record the
percent growth:
F. after 2 hours only.
G. after 4 hours, then again after 6 hours.
H. after 8 hours only.
J. every 15 minutes for 3 hours.
Multiple Choice Answers
1. The best answer is C. Table 1 shows that Petri dish 2 had a pH level of 7 and experienced the highest
percent growth of E. coli bacteria, as compared to Petri dishes 1 and 2. Therefore, answer choice C, a pH
level near 7, is correct.
2. The best answer is F. The description of Experiment 3 indicates that MOST bacteria, unlike E. coli,
need certain growth factors and vitamins to reproduce. In addition, the experiment was run to “ensure
that the three growth factors have minimal to no effect on growth.”
3. The best answer is A. Table 1 shows that E. coli bacteria reproduce most efficiently at a pH level of 7,
so answer choice A is correct. Answer choice D is not correct because Table 1 shows that E. coli can still
reproduce at different pH levels, just not as efficiently.
4. The best answer is G. The question states that bacteria often reproduce until all available nutrients
have been depleted. By supplying each group of bacteria with unlimited nutrients, the bacteria will
reproduce for a longer time.
5. The best answer is C. According to Table 2, Petri dish 1, with the highest percent dry weight of the
organic compounds (nutrients), yielded the highest percent growth of E. coli bacteria. This best supports
the statement in answer choice C.
6. The best answer is J. Since the reproduction rate varies drastically from one stage to the next, the best
way to study the different growth stages would be to record the growth changes more frequently.