A Level Biology Practice Exam

How is oxygen tension measured?

1. In units of temperature

2. In percentage of total volume

3. In units of pressure (kPa)

4. In pH levels of blood

The correct answer is: In units of pressure (kPa)

Oxygen tension is a measure of the partial pressure of oxygen in a mixture of gases or in a particular environment, such as blood. It is specifically expressed in units of pressure, which commonly include kilopascals (kPa). This measurement indicates how much oxygen is available for diffusion, which is crucial for understanding respiratory physiology and gas exchange in biological systems. In this context, measuring oxygen tension in terms of pressure allows scientists and medical professionals to assess how well oxygen is being transported and utilized in the body. This is especially important in clinical settings, where precise values can inform treatment decisions for respiratory conditions. The other options do not accurately describe how oxygen tension is measured. Temperature units do not convey information about gas concentrations. Percentage of total volume could be used to describe concentration but does not provide a true partial pressure measurement, which is more relevant to the behavior of gases. Lastly, pH levels relate to acidity and alkalinity and do not reflect oxygen tension in the bloodstream directly.