Crocodile hemoglobin does not bind 2,3-BPG. Instead, it binds bicarbonate ion, which is a strong negative allosteric effector. Why might crocodiles have a hemoglobin that is responsive to HCO-3 instead of 2,3-BPG? Recall that crocodiles hold their prey underwater to kill them. a. As the crocodile stays underwater, its hemoglobin delivers most of the bound HCO-3 as a result of decreased binding of O2 to the R conformation.

b. As the crocodile stays underwater, its hemoglobin delivers most of the bound O2 as a result of increased binding of HCO-3 to the T conformation.

c. As the crocodile stays underwater, its hemoglobin delivers most of the bound O2 as a result of decreased binding of HCO-3 to the R conformation.

d. As the crocodile stays underwater, its hemoglobin delivers most of the bound HCO-3 as a result of increased binding of O2 to the T conformation.

b) is the correct option

Explanation:

In tissues CO2 enter in red blood cells and converted into HCO-3 with the release of H + ion; reaction is catalysed by carbonic anhydrase enzyme

Released H + ions reduces pH of cells and facilitate dissociation of oxygen from hemoglobin

This is favored by T state which occurs in tissues

Hemoglobin mainly exists in two conformations: T state and R state

T state consists of deoxygenated hemoglobin, less affinity for oxygen and is favored by tissues

R state consists of oxygenated hemoglobin, high affinity for oxygen and is favored by lungs

T state is dominant conformation of deoxy hemoglobin and stabilized by ionic interactions whereas oxygen binding stabilizes R state

Here in case of crocodile, underwater there is increased binding of HC0-3 to the T state because there is less affinity for oxygen underwater hence T state will be dominant