ACT Science

A new drug is in its clinical trial phase. The graph below shows the data for participants sleep patterns before medication use and then after using the medication for three months. Series 1 shows the average hours slept a night for each participant prior to medication. Series 2 shows the average hours slept a night for each participant after three months of use. The average hours slept a night was obtained by recording sleep every night for one month, and then finding the average. Patients one through five took a placebo pil, not the actual Moonlight medication. Note: The y-axis is measured in hours slept a night, while the x-axis lists each anonymous patient numerically.

1. The overall trend when comparing sleep before and after mediciation use is __________.
2. What information would strengthen the experiment?
Sleep plays a vital role in defining the daily activities of virtually all animals. During periods of sleep, the parasympathetic nervous system becomes active and induces a relaxed state in response to increased levels of the hormone melatonin. Yet, despite its ubiquity in the animal kingdom, the purpose of sleep and its role in our daily lives has been disputed by scientists. Two scientists discuss their theories about the purpose of sleep.

Scientist 1
During periods of sleep, animals are able to conserve energy that they would otherwise be spending on unnecessary activity. If an animal’s primary food source is most abundant during daylight, it is a waste of precious energy to be moving about at night. For example, many herbivores, such as squirrels, are diurnal (sleep during the night) because their food source is available during the day, while many insectivores, such as bats, are nocturnal (sleep during the day) because their food source is available during the night. Food sources, as an animal’s most valuable resource, dictate their sleep cycles. Many animal traits observable today evolved as a result of the supply and demand of food in their natural habitat.

Scientist 2
During waking hours, it is true that the body utilizes large amounts of energy. However, the role of sleep is to restore biological products that were utilized during periods of wakefulness, rather than simply avoid utilizing energy in the first place. Many types of biological molecules, such as hormones, are released throughout the body while an animal is active. Sleep serves as a period of inactivity during which the body can manufacture and store a supply of these molecules for future use during the next period of activity. Furthermore, sleep allows the body to repair cellular damages that has accumulated during waking hours. Experimental evidence shows that when animals are deprived of sleep, their immune system quickly weakens and death rates increase. Sleep is necessary for animals to prevent accumulation of damage and to regenerate crucial biomolecules for daily life.

3. Both scientists give evidence to support their theories. The evidence given by Scientist 1 can best be described as __________.
4. Both scientists give evidence to support their theories. The evidence given by Scientist 2 can best be described as __________.
5. Which of the following, if true, would most support Scientist 1?
6. Which of the following, if true, would most support Scientist 2?
An experiment was done to test the antibiotic resistance of the bacteria Pseudomonas flourescens and Escherichia coli by using the antibiotic disk sensitivity method. Four different antibiotics were tested on each bacterium. Media were prepared with each type of bacterium and a drop of each antibiotic was added to each corner of the plates, a different antibiotic in each corner. The cultures were observed for eighteen hours. After this period of time, the zones of inhibition (where the bacteria was not able to grow due to the antibiotic) were measured. The table below shows the results of the four antibiotics on the two bacteria, Pseudomonas flourescens and Escherichia coli.

7. Which of the following changes would weaken the experimental results?
8. Which change to the experimental design would strengthen the results?
Three doctors are discussing the most optimal way to approach cancer treatment. While they all acknowledge that cancer is uncontrolled cell proliferation, they have different opinions on whether chemotherapy is the best treatment method. Chemotherapy is the treatment of cancer with cytotoxic antienoplastic drugs. These drugs are used to kill fast-growing cancerous cells. All three doctors agree that chemotherapy has many associated side effects.

Doctor 1
While the drugs used for chemotherapy can be very strong, they need to be. Cancer, by its very definition, is made up of cells growing at a faster than normal rate. This means the treatment needs to be aggressive. The slower the effects of treatment, the more time the cancer has to spread; therefore, while the chemotherapy can also kill some healthy noncancerous cells in the process, it is still the best option.

Doctor 2
Chemotherapy does much more harm than good. Chemotherapy might temporarily destroy the cancer, but it does not cure the cancer. In addition, killing the cancerous cells means poisoning the body with chemicals and toxins. Instead, we should be addressing the reasons cancer exists in the first place, treating it at that step. Cancer is due to toxins in the body, industrial pollutions, and drugs. Avoiding sugar, exercising, and maintaining a healthy lifestyle—free of toxins, processed food, and other containments—is the best approach.

Doctor 3
Chemotherapy is effective in the sense that it kills the cancer cells. The downfall is that chemotherapy also kills the healthy cells in the process; therefore, we should be looking at way to decrease the amount of chemotherapy needed, so that we are only introducing the minimum amount of toxins into the body. Insulin Potentiating Therapy is a type of chemotherapy in which lower doses of chemotherapy are used because they are combined with insulin. Cancer cells have more insulin receptors than non-cancerous cells; therefore, cancer cells will have a biased absorption of such insulin-based chemotherapy when compared with noncancerous cells. In other words, piggybacking chemotherapy onto insulin allows cancer cells to absorb more of the chemotherapy, meaning less chemotherapy is needed and fewer noncancerous cells absorb the chemotherapy.

9. Which of the following best states the opinion of Doctor 1?
10. What fact do all three doctors seem to agree upon?
Two students are studying hydrocarbon combustion, or the burning of compounds containing carbon and hydrogen in the presence of oxygen gas. Both students express their views on this phenomenon.

Student 1: Hydrocarbons are high in energy and therefore naturally burn in order to release that energy. That energy is released in the form of light and heat. If water is thrown onto a fire, it will extinguish it because it cuts the combustion from the oxygen gas required for it to burn.

Student 2: Hydrocarbons are compounds at a greater energy state than the compounds produced when they burn. This excess energy changes to heat when hydrocarbons burn. Lastly, hydrocarbons require a spark to initiate the combustion.

11. Which of the following statements would both students be most likely to agree?
12. Which of the following statements would Student 2 be most likely to agree with and not Student 1?
13. At a constant pressure and volume, the relationship between the number of moles and temperature may best be modeled as:
14. At a constant pressure, the relationship between volume and temperature may best be shown as:
15. What is a controlled variable in this experiment?
16. Based on the information in Table 1, what variables must be measured in order to calculate the energy of the food samples?
17. In an oxygen molecule, O2, the two oxygen atoms oscillate about a fixed central point. Which form of kinetic energy is best described here?
18. An oxygen molecule moving from the left side of a chamber to the right would display what type(s) of kinetic energy?
19. In order to display the relationship between the number of moles of H+ and the rate of the reaction in Experiments 1 and 4, the scientist could:
20. The effect of temperature on the rate of reaction is best demonstrated by comparing which two trials?
21. A red-shift can be used to estimate_________.
22. Which model suggests a greater age of the universe?
23. A primordial gas has less mass than ________.
24. The discovery of primordial gas clouds supports which theory?
25. On the comet, the best description of the relationship between depth of sampling and the concentration of organics is:
26. The units expressing the concentration of organic molecules in the samples from Mars and comet are in mg/L. This unit is most precisely a measure of:
27. In order to replicate the above study, which of the following must be known?
28. In Table 2, what is the most likely explanation for the varying concentrations of spores from Plant 1 across each sample?
29. A new planet is discovered 11 megaparsecs (MPSC) away from the Earth. Which of the following is its likely velocity?
30. Two planets, one with mass x, the other with mass 2x, are the same distance away from Earth. What will their relationship be in terms of their velocity, v?
31. If the students' hypotheses were correct, what might be a worthwhile question for them to study next?
32. Suppose a second group of students hypothesizes that the velocity of sound is inversely dependent upon the density of the substance through which the sound travels. Which study would best support their hypothesis and why?
33. According to Study 2, over what temperature interval does velocity begin to decrease as water temperature rises?
34. According to the data in Study 1, as density increases, what happens to the velocity of sound?
35. Jackie read about this experiment and decided to recreate Study 1. She found that each of the velocities she measured are higher than those in the original experiment. What is one possible explanation for this difference?
36. A second scientist is examining this data and wants to test if introducing an electric field around the ramp in Experiment 1 changes the measured energy values. To do this, he sets up another system, identical to that in Experiment 1, but with the addition of an electric field. He compares data generated by both the original system in Experiment 1 and the new system with the electric field. Experiment 1 is now serving as what?
37. The results of experiments 3 and 4 show that __________.
38. Which of the following represents the order of charge of the four particles, from highest to lowest?
39. The experiment is set up correctly and measurements are taken. If 0 fringe shifts are measured, what can we conclude from the experiment?
40. If a measured fringe shift is written as 5±1, where 1 represents the uncertainty, what is the percent uncertainty?
ACT Science
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