In a study of fur pigmentation in deer mice, Peromyscus polionotus, scientists compared the brightness

In a study of fur pigmentation in deer mice, Peromyscus polionotus, scientists compared the brightness of the fur of mice from populations located different distances directly inland from a coastal site. Figure 1 shows the 2 facial regions and the 2 body regions at which the fur of each mouse was evaluated (on a scale from 0 to 1.00) with respect to its brightness.

Figure 1 also shows how, for each of the 4 regions, average relative brightness varied with inland distance.

Figure 2 shows how the average brightness of surface soil samples, given as the average percent relative reflectance, varied with inland distance.

1. Based on Figure 2, on average, where was the brightest surface soil found?

  1. At the coastal site
  2. 50 km inland
  3. 100 km inland
  4. 150 km inland

2. According to Figure 1, the average relative brightness of the dorsal stripe was 0.25 at an inland distance that was closest to which of the following?

  1. 20 km
  2. 40 km
  3. 60 km
  4. 80 km

3. According to Figure 1, the greatest change in the average relative brightness of the fur on the rostrum occurred between which of the following inland distances?

  1. 0 km and 25 km
  2. 25 km and 50 km
  3. 50 km and 75 km
  4. 100 km and 125 km

4. Based on Figure 1, on average, was the fur pigmentation on the ventrum of P. polionotus lighter or darker 150 km inland than it was at the coastal site?

  1. Lighter, because the average relative brightness 150 km inland was greater.
  2. Lighter, because the average relative brightness 150 km inland was less.
  3. Darker, because the average relative brightness 150 km inland was greater.
  4. Darker, because the average relative brightness 150 km inland was less.

5. Which of the following statements best explains the geographic variation in the fur pigmentation of P. polionotus ? At any given inland distance, the more closely the fur pigmentation of a P. polionotus mouse matches the soil, the:

  1. less likely the mouse will be found by a predator, and thus the less likely it will pass its fur pigmentation traits to its offspring.
  2. less likely the mouse will be found by a predator, and thus the more likely it will pass its fur pigmentation traits to its offspring.
  3. more likely the mouse will be found by a predator, and thus the less likely it will pass its fur pigmentation traits to its offspring.
  4. more likely the mouse will be found by a predator, and thus the more likely it will pass its fur pigmentation traits to its offspring.

6. Based on Figure 2, on average, was the surface soil at the coastal site lighter or darker than the standard that was used for the comparison?

  1. Lighter; the average percent relative reflectance of the soil at the coastal site was 100%.
  2. Lighter; the average percent relative reflectance of the soil at the coastal site was less than 100%.
  3. Darker; the average percent relative reflectance of the soil at the coastal site was 100%.
  4. Darker; the average percent relative reflectance of the soil at the coastal site was less than 100%.

Answers

1. The correct answer is A.

According to the passage, the percent relative reflectance shown in Figure 2 is based on a comparison to a standard with 100% reflectance. The higher the percent reflectance, the brighter the soil. According to Figure 2, the highest average percent relative reflectance was 70% measured at an inland distance of 0 km. In other words, this measurement was made at the coastal site, so A is correct.

2. The correct answer is C.

According to Figure 1, the average relative brightness of the dorsal stripe was 0.25 at an inland distance of approximately 60 km.

3. The correct answer is C.

According to Figure 1, on the graph representing the brightness of the fur on the rostrum, the line is steepest between inland distances of 50 km and 65 km, indicating that this is where there was the greatest change in the average relative brightness of the fur on the rostrum.

4. The best answer is D.

According to Figure 1, 150 km inland the average relative brightness of the ventrum fur was 0 whereas at the coastal site it was 1.00. The fur was brighter at the coastal site than 150 km inland. The fur was darker 150 km inland.

5. The correct answer is B.

In order to answer this item, you must know that natural selection is the survival and reproduction of organisms because of environmental forces that result in favorable adaptations. If the fur pigmentation matches the soil, then it will increase the chances of the mouse’s survival, and it will be more likely to pass these traits on to its offspring.

6. The correct answer is D.

According to Figure 2, the standard had 100% reflectance. Because the soil at the coastal site had an average percent relative reflectance of 70%, the soil was darker than the standard.