A Level Biology Practice Exam

What is lymph?

1. Blood plasma without cells

2. Modified tissue fluid collected in the lymph system

3. A component of red blood cells

4. Interstitial fluid that remains in tissues

The correct answer is: Modified tissue fluid collected in the lymph system

Lymph is indeed best described as modified tissue fluid collected in the lymphatic system. It originates from interstitial fluid that bathes cells and is formed when this fluid enters lymphatic capillaries. As the fluid is transported through the lymphatic vessels, it undergoes modifications, including the filtration of pathogens and cellular debris, which are managed by lymph nodes. This modification process is crucial for the immune response, as lymph carries lymphocytes and other immune cells that help defend against infection. Understanding the role of lymph as a component of the lymphatic system illustrates its importance in fluid balance and immune function in the body.