Question

The solubility of \(\mathrm{O}_{2}\) in aqueous solutions-such as seawater or blood plasma-increases as temperature decreases. Moreover, the rates at which tissues metabolically consume \(\mathrm{O}_{2}\) tend to decrease as temperature decreases. With these facts in mind, explain whyin the world's oceans-polar seas are the most likely place where fish could survive a mutation that deletes their ability to synthesize blood hemoglobin.

Short answer

Fish could survive a mutation that deletes their ability to synthesize hemoglobin in polar seas due to the increased solubility of oxygen in colder waters and the decreased oxygen demand of the fish at lower temperatures.

Step-by-step solution

Understand the role of hemoglobin

Hemoglobin is a protein in red blood cells that transport oxygen from the lungs to the body’s tissues and returns carbon dioxide from the tissues back to the lungs. If fish were to lose their ability to synthesize hemoglobin, they would struggle to transport enough oxygen around their bodies.

Understand the impact of temperature on oxygen solubility

The solubility of \(\mathrm{O}_{2}\) in aqueous solutions such as seawater or blood plasma increases as temperature decreases. This means that in colder environments, more oxygen can be dissolved in water.

Understand the effect of temperature on metabolic oxygen consumption

The rates at which tissues metabolically consume \(\mathrm{O}_{2}\) tend to decrease as temperature decreases. In other words, fish in colder waters need less oxygen to survive as their metabolic rates are lower.

Relate the above facts to the survival of fish

If a fish were to lose their ability to synthesize hemoglobin, they would need to rely more on the direct diffusion of oxygen from the water into their tissues. In the polar seas, where temperatures are lower, there is a higher concentration of dissolved oxygen in the water, and the metabolic rates of the fish are lower. Therefore, despite the lack of hemoglobin, the fish in colder waters could still theoretically get enough oxygen to survive due to the higher solubility of oxygen in cold water and reduced oxygen demand at lower temperatures.

Key concepts

Hemoglobin

Hemoglobin is a critical protein found in red blood cells, vital for transporting oxygen throughout the body. It binds to oxygen in the lungs and carries it to tissues needing oxygen to maintain cellular functions. Without hemoglobin, oxygen transfer in organisms would be inefficient.

This protein also plays a key role in eliminating carbon dioxide, a waste product of cellular respiration, from the tissues and transporting it back to the lungs for exhalation. Thus, hemoglobin facilitates both essential oxygen delivery and carbon dioxide removal. In the context of fish, efficient oxygen transport through hemoglobin is crucial for their survival, especially for metabolic activities that demand constant oxygen supply.

Metabolic Rates

Metabolic rates refer to the speed at which organisms convert nutrients into usable energy. This process requires a constant supply of oxygen. In fish, metabolic rates dictate their energy expenditure and, consequently, their oxygen needs.

As environmental temperatures decrease, as is the case in colder waters, metabolic processes slow down. This results in reduced oxygen consumption since cellular activities decrease. Lower metabolic rates in cold environments mean fish require less energy and oxygen to sustain life functions. Furthermore, this reduced demand aligns well with the increased oxygen availability at lower temperatures, reducing reliance on efficient oxygen transport mechanisms such as hemoglobin.

Polar Seas

Polar seas are unique marine environments characterized by extremely cold temperatures. These bodies of water, such as the Arctic and Antarctic regions, provide conditions that significantly influence oxygen dynamics.

In these icy waters, oxygen solubility is notably higher, meaning more oxygen can dissolve into the water. This high solubility is partly due to the colder temperatures, which slow molecular movement, allowing gas molecules like oxygen to remain dissolved longer.

• Higher dissolved oxygen levels benefit aquatic life, particularly those with inefficient oxygen transportation systems.
• The cold also slows down metabolic rates of polar marine creatures, further optimizing conditions for survival despite reduced oxygen needs.

This phenomenon is especially advantageous for fish in polar regions that might lack the ability to synthesize hemoglobin.

Fish Adaptation

Fish have evolved a multitude of adaptations to thrive in diverse environments, and polar seas present unique challenges that drive certain evolutionary traits. In the absence of hemoglobin synthesis, fish must rely on direct oxygen absorption from water.

Adaptations in polar fish typically include enhanced gill structures that maximize oxygen uptake directly from the water column due to higher dissolved oxygen levels.

• They may exhibit slower metabolic rates to reduce oxygen demand, aligning with colder temperatures that naturally decrease metabolic activity.
• Additionally, these fish often have specialized blood and cellular compositions that improve oxygen diffusion efficiency.

These adaptations are crucial for survival, especially when traditional oxygen transportation systems are compromised, allowing fish to thrive even in the challenging conditions of polar seas.