OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What substances does plasma transport around the body?

1. Red blood cells

2. Hormones

3. Carbon dioxide from cells to lungs

4. All of the above

The correct answer is: All of the above

Plasma, which is the liquid component of blood, plays a crucial role in transporting various substances throughout the body. It carries red blood cells, which are essential for oxygen transport, but it also serves as a medium for many other components. Hormones, produced by glands and released into the bloodstream, are dissolved in plasma and transported to target organs where they exert their effects. This is vital for coordinating many physiological processes in the body, such as growth, metabolism, and the regulation of mood. Carbon dioxide, a waste product of cellular respiration, is also transported in plasma. It is carried from the tissues, where it is produced, to the lungs, where it can be expelled from the body during exhalation. This process is essential for maintaining acid-base balance and overall respiratory function. Since plasma is responsible for the transportation of red blood cells, hormones, and carbon dioxide, it effectively facilitates the movement of all these substances. Thus, the most comprehensive answer reflects its multifunctional role in the circulatory system.