Biological Systems MCAT Practice Exam

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Prepare for the Biological Systems MCAT. Study with detailed questions and explanations. Enhance your understanding and boost your confidence for this crucial exam.

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What effect does an increase in carbon dioxide have on hemoglobin's affinity for oxygen?

Increases affinity
No effect
Decreases affinity
Shifts curve to the left

The correct answer is: Decreases affinity

An increase in carbon dioxide concentration decreases hemoglobin's affinity for oxygen. This phenomenon occurs due to the Bohr effect, where increased levels of carbon dioxide and the corresponding drop in pH (due to the formation of carbonic acid) lead to a conformational change in hemoglobin. This change makes it less able to bind oxygen, facilitating the release of oxygen in tissues that are actively metabolizing and producing carbon dioxide. The decrease in affinity ensures that tissues with high levels of carbon dioxide can receive the oxygen they need for aerobic respiration. This understanding is critical because it illustrates the dynamic relationship between carbon dioxide levels and oxygen delivery in the body, highlighting how metabolic activity can influence gas exchange.