Carp are fishes that thrive in stagnant-water habitats with low oxygen partial pressure. Compared with the hemoglobin of many other fish species, carp hemoglobin has an extremely high affinity for O2. Draw an oxygen–hemoglobin equilibrium curve showing separate lines for carp and a fish that lives in water with a higher oxygen partial pressure. Explain why they differ.

Verified step by step guidance

1. Step 1: Understand the concept of an oxygen-hemoglobin equilibrium curve. This curve plots the percentage saturation of hemoglobin with oxygen (on the y-axis) against the partial pressure of oxygen (on the x-axis).
2. Step 2: Recognize that carp hemoglobin has a higher affinity for oxygen compared to other fish. This means that at any given partial pressure of oxygen, carp hemoglobin will be more saturated with oxygen than hemoglobin from other fish.
3. Step 3: Draw the curve for carp. Start the curve higher on the y-axis at lower partial pressures of oxygen, indicating that even at low oxygen levels, carp hemoglobin is quite saturated with oxygen. The curve should rise quickly and plateau, showing that saturation occurs at relatively low oxygen pressures.
4. Step 4: Draw the curve for a fish living in higher oxygen environments. This curve will start lower on the y-axis at the same partial pressures, indicating less saturation at these levels. The curve will rise more gradually, showing that higher oxygen pressures are needed to achieve similar levels of hemoglobin saturation as in carp.
5. Step 5: Explain the differences: Carp live in stagnant, low-oxygen environments, so their hemoglobin has evolved to bind oxygen more efficiently at these lower concentrations to adequately supply their tissues. Fish in higher oxygen environments do not require such an adaptation, so their hemoglobin has a lower affinity for oxygen, requiring higher oxygen pressures to achieve similar saturation levels.

Key Concepts

Oxygen-Hemoglobin Dissociation Curve

The oxygen-hemoglobin dissociation curve illustrates the relationship between the partial pressure of oxygen (pO2) and the saturation of hemoglobin with oxygen. It typically has a sigmoidal shape, indicating that hemoglobin's affinity for oxygen increases as more oxygen molecules bind. This curve can shift based on environmental factors, such as pO2 levels, affecting how efficiently hemoglobin can pick up and release oxygen.

Hemoglobin Affinity for Oxygen

Hemoglobin's affinity for oxygen refers to how readily hemoglobin binds to oxygen molecules. In species like carp, which inhabit low-oxygen environments, hemoglobin has evolved to have a higher affinity for oxygen, allowing them to extract oxygen more efficiently from the water. This adaptation is crucial for survival in stagnant waters where oxygen levels are limited.

Environmental Adaptations in Aquatic Species

Aquatic species exhibit various adaptations to thrive in their specific environments, particularly concerning oxygen availability. Fish living in high-oxygen environments typically have hemoglobin with a lower affinity for oxygen, allowing for efficient oxygen release to tissues. In contrast, species like carp, which live in low-oxygen habitats, have adaptations that enhance oxygen uptake, reflecting the evolutionary pressures of their respective environments.