The crocodile, which can remain under water without breathing for up to one hour, drowns its air-breathing prey and then dines a
t its leisure. An adaptation that aids the crocodile in doing so is that it can utilize virtually 100% of the oxygen in its blood, whereas humans, for example, can extract only approximately 65% of the oxygen in their blood. Crocodile Hb does not bind BPG. However, crocodile deoxy Hb preferentially binds bicarbonate ions. How does this help the crocodile remain under water for so long?
Crocodile deoxy Hb preferably binds bicarbonate ions. This helps the crocodile stay underwater for so long because it allows a series of reactions that ends with the release of O2 into the crocodile's organism.
Explanation:
When the crocodile spends a lot of time underwater, the CO2 concentrations in its body increases. When the CO2 concentration increases, an increase in the HCO3- concentration is allowed in the cell simultaneously. This HCO3 is precisely the substrate that deoxy Hb needs to help the crocodile stay underwater. That's because when deoxy Hb binds to HCO3, the enzyme allows hemoglobin to assume a deoxy conformation by releasing O2 into the crocodile organism.
As millions of Americans switch to the new diet, we can expect a(n) _decrease____ in the __demand for___ beef, leading to a shift to the __left___ in the __demand___ curve for beef and _lower____ beef prices.
