Final answer:
The term for the enhanced binding of oxygen to a molecule due to the presence of an already bound oxygen molecule is called cooperativity; however, this is more applicable to hemoglobin than myoglobin. The Haldane effect refers to the increased affinity of hemoglobin for carbon dioxide when the partial pressure of oxygen is low.
Step-by-step explanation:
The idea that binding of one molecule of oxygen to myoglobin enhances further binding of oxygen to myoglobin is called cooperativity. This phenomenon is observed with hemoglobin rather than myoglobin. Myoglobin, which is primarily found in muscle tissues, has a hyperbolic oxygen binding curve and does not exhibit cooperativity. It binds oxygen with a constant affinity. In contrast, for hemoglobin, as one molecule of oxygen binds, it increases the affinity for the next oxygen molecules, resulting in the characteristic S-shaped or sigmoidal oxygen binding curve for hemoglobin due to cooperative binding.
Addressing question 27, a low partial pressure of oxygen promotes hemoglobin binding to carbon dioxide. This is known as the Haldane effect. It describes how deoxygenated blood has a higher affinity for carbon dioxide, which is relevant in the transport of carbon dioxide from the tissues to the lungs for exhalation.