Question 10 Answer and Explanation _ACT April 2013 Form 71G Science Section

Passage II

Bone mineral density (BMD) is an indicator of overall bone health. Low BMD increases the risk for bone fracture. Scientists have determined that BMD is linked to dietary intake. Two studies, one with humans and one with rats, examined the effect of caffeinated cola consumption on BMD.

Study 1

A food-and-drink questionnaire was given to 1,413 adult women who had an average age of 58.2 yr. Each woman was assigned to 1 of 5 groups according to her caffeinated cola consumption. The average BMD for each group is shown in Figure 1.

Figure 1 adapted from Katherine L. Tucker et al., "Colas, but Not Other Carbonated Beverages, Are Associated with Low Bone Mineral Density in Older Women: The Framingham Osteoporosis Study." @2006 by American Society for Nutrition.

Study 2

Thirty 10-week-old rats were divided into 4 groups: Groups 1 and 2 consisted of 10 male and 10 female rats, respectively; Groups 3 and 4 consisted of 5 male and 5 female rats, respectively. Each rat in Groups 1 and 2 was provided with unlimited supplies of a solid rat food, drinking water, and caffeinated cola for 30 days. Each rat in Groups 3 and 4 was provided with unlimited supplies of the rat food and drinking water, but no cola, for 30 days. Figure 2 shows, for each group, the average daily caffeinated cola consumption per rat, the average daily drinking water consumption per rat, and the average daily total fluid consumption per rat.

Figure 3 shows, for each group, the average BMD on Day 30.

Figures 2 and 3 adapted from Recai Ogur et al., "Evaluation of the Effect of Cola Drinks on Bone Mineral Density and Associated Factors." @2007 by Nordic Pharmacological Society.

10. The BMDs of the subjects in Studies 1 and 2 were determined by scans of their hip bones. Based on Figures 1 and 3, was the average BMD for any group of rats greater than or less than the average BMD for any group of women?

F. Greater; a rat’s hip bone is less dense than is a woman’s hip bone.

G. Greater; a rat’s hip bone is more dense than is a woman’s hip bone.

H. Less; a rat’s hip bone is less dense than is a woman’s hip bone.

J. Less; a rat’s hip bone is more dense than is a woman’s hip bone.

Answer and Explanation

Your Answer is

Correct Answer is H

Explanation

First of all, it can be seen from table 1 that the lowest BMD of females is also greater than 0.85;

As can be seen in figure 3, the highest value of BMD of mice is less than 0.16, so the BMD of mice is less than 0.16. Women are lower