Myoglobin (Mb) Levels in the Cardiac Tissue of Three Teleost Species
| Species | Heart tissue color | Average Mb level | Standard deviation of Mb level | Number of healthy fish observed |
|---|---|---|---|---|
| Bunocephalus coracoideus | red | 18.02 | 0.59 | 3 |
| Chitala chitala | red | 4.75 | 1.07 | 4 |
| Pantodon buchholzi | white | 0.02 | 0.01 | 4 |
Myoglobin (Mb) is a protein that primarily aids in oxygen storage and diffusion across the mitochondrial membrane in cardiac muscle cells; these are necessary functions in sustaining aerobic metabolism. Macqueen et al. studied myoglobin concentrations across fish species and concluded that species with white cardiac tissue have minimal myoglobin presence compared to species with red cardiac tissue.
Which choice most effectively uses data from the table to support Macqueen et al.'s conclusion?
Explanation
Context: Macqueen et al. concluded that fish species with white cardiac tissue have minimal myoglobin (Mb) compared to species with red cardiac tissue. In the table, the red-tissue species B. coracoideus and C. chitala average 18.02 and 4.75, while the white-tissue species P. buchholzi averages only 0.02.
Answer: C) P. buchholzi had very low Mb levels in their cardiac tissue.
Why? P. buchholzi is the table's white-tissue species, and its 0.02 average is barely above zero, minimal beside the red-tissue averages of 18.02 and 4.75. Pointing to that near-zero value directly supports the claim that white cardiac tissue goes with minimal myoglobin.
Traps:
- A) It links higher averages to greater variance, which the conclusion never mentions; the table even contradicts it, since B. coracoideus has the highest average (18.02) with a smaller standard deviation (0.59) than C. chitala (1.07)
- B) Placing B. coracoideus above both other species groups the red-tissue C. chitala with the white-tissue P. buchholzi, so it never isolates the white-versus-red comparison
- D) Standard deviations (0.01 versus 0.59 and 1.07) describe consistency among individual fish, not whether white-tissue species carry less myoglobin