Question

the oceanic whitetip shark and the pacific halibut are ectothermic (cold - blooded) fish, whereas the shortfin mako shark and the yellowfin tuna are regional endotherms - they retain metabolic heat resulting in body temperatures above the ambient water temperature. modeling the effect of falling ambient temperatures on ectotherms indicated to researchers haley r. dolton and colleagues that ectotherms body temperatures inexorably decrease toward the ambient temperature. data from wild basking sharks show that even though their body temperature consistently remains 1.0 to 1.5°c above ambient, it also declines as the ambient temperature falls. this suggests that the body temperatures of the ___ image which choice most logically completes the text? a) yellowfin tuna and the shortfin mako shark are likely to be more variable than the body temperature of the basking shark. b) pacific halibut and the basking shark are at least partly determined by the ambient water temperature. c) basking shark and the shortfin mako shark remain fixed even as ambient water temperature changes, while the body temperature of the pacific halibut changes with variations in the ambient water temperature. d) basking shark and the yellowfin tuna remain fixed even if the ambient water temperature changes, while the body temperature of the oceanic whitetip shark varies even if the ambient temperature is stable.

Explanation:

The text is about the body temperatures of different marine animals (sharks, halibut, tuna) and how they relate to ambient water temperature. Ectotherms (like halibut) have body temperatures that change with ambient water temperature. Endotherms (like shortfin mako shark) can retain metabolic heat. The key is to analyze each option:

• Option A: Yellowfin tuna and shortfin mako shark are likely endotherms (as they can retain heat), so their body temperature is less variable than basking shark (which is more affected by ambient temperature as an ectotherm - though basking shark's case is a bit more complex in reality, but based on text logic).
• Option B: Pacific halibut is ectothermic (cold - blooded), so its body temperature is affected by ambient, not the other way around.
• Option C: Basking shark's body temperature is affected by ambient (as per text: "even though their body temperature remains 1.0 to 1.5°C above ambient, it also declines as the ambient temperature falls"), so it's not that ambient changes with its body.
• Option D: Basking shark's body temperature changes with ambient (as per text description of temperature relation).

Answer:

A. yellowfin tuna and the shortfin mako shark are likely to be more variable than the body temperature of the basking shark.