ACT science practice test 46

Directions: Each passage is followed by several questions. After reading a passage, choose the best answer to each question and fill in the corresponding oval on your answer document. You may refer to the passages as often as necessary.

You are NOT permitted to use a calculator on this test.

The sun is a source of many wavelengths of radiation that reach the earth. The earth's atmosphere absorbs some of these wavelengths, while others are able to penetrate and reach the planet's surface. Ultraviolet radiation from the sun comes in three different categories based on wavelength and penetration: UVA, UVB, and UVC.

UVB radiation has wavelengths of 280 to 320 nm and is partially absorbed by the earth's ozone layer. The UVB rays that do reach the surface can be absorbed by human skin and have been known to cause sunburn and many forms of skin cancer. Many products, from glasses to sunscreen, have been created to help protect humans from UVB radiation. Two groups of students set out to test the ability of materials to block UVB light, using a computer and a sensor specifically designed to detect UVB radiation.

Group 1

The members of Group 1 placed a sensor in full sunlight and shielded the sensor with a variety of sunglasses claiming to offer UVB protection. A reading was taken on the UVB sensor for each product, and the data were recorded in Table 8.1.


Group 2

The members of Group 2 placed a sensor in the sun and shielded that sensor with a piece of glass. They tested sunscreens of increasing SPF (sun protection factor) on the glass, and the data were recorded in Table 8.2.


1. In Group 2's experiment, SPF is the independent variable being manipulated and UVB is the dependent variable being measured. Which of the following graphs best represents the relationship between the SPF and UVB data from this experiment?

Figure 8.1
Figure 8.2
Figure 8.3
Figure 8.4

2. Which of the following questions could the students in Group 2 be attempting to answer using the data from their experiment?

A. Does the cost of sunscreen affect the amount of UVB that is blocked?
B. Which brand of sunscreen is the best?
C. Is there a relationship between SPF and the amount of UVA radiation blocked?
D. Can sunscreen protect humans from skin cancer?

3. According to the findings of Group 1:

A. there is a negative correlation between price and the ability to protect from UVB radiation.
B. there is a positive correlation between price and the ability to protect from UVB radiation.
C. there is no correlation between the price of a pair of sunglasses and their ability to protect the eyes from UVB radiation.
D. sunglasses do not protect the eyes from UVB radiation.

4. Assuming that the sunscreen being tested was purchased in 10-oz bottles, which sunscreen had the best cost for the amount of UVB protection (use the formula $/mW/m2 of UVB blocked)?

A. SPF 50
B. SPF 30
C. SPF 8
D. SPF 4

5. Which of the following is MOST likely to represent a control that would have been used to ensure reliability of data in the experiment done by Group 2?

A. The distance from the sunglasses to the sensor
B. The ingredients in the sunscreen being used
C. A longer time for the sensor readings as SPF increased
D. The amount and thickness of sunscreen being spread on the glass

6. According to the results of Group 1's experiment, what percentage of UVB rays would a $200 pair of sunglasses block?

A. 99.50%
B. 99.70%
C. 99.60%
D. There is not enough information to determine this answer.

7. Based on the results of Group 2's experiment, what would the UVB reading most likely be if SPF 60 sunscreen were to be tested?

A. 18 mW/m2
B. 19.25 mW/m2
C. 9.25 mW/m2
D. 4.5 mW/m2

8. Which of the following is the experimental variable that Group 1 manipulated?

A. The time of day
B. The type of sunglasses
C. The amount of UVB rays
D. The distance of the materials from the sensor

9. Which of the following implies the correct relationship between SPF and UVB blockage?

A. Sunscreens with SPFs higher than 30 provide only a marginal increase in sun protection over their counterparts with lower SPFs.
B. As SPF increases, the ability to block UVB light decreases.
C. There is no correlation between SPF and UVB blockage.
D. Sunscreens with higher SPFs provide less sun protection than those with low SPFs.

10. What other experiment could the students in Group 2 conduct using the same equipment?

A. The effect of sunscreen on shielding UVA rays
B. The ability of sunscreen to prevent cancer
C. How the amount of sunscreen applied can impact the SPF
D. The margin of benefit of SPF sunscreens higher than 60