A Level Biology Practice Exam

What is the function of tylose in xylem vessels?

1. It absorbs water from the soil

2. It blocks the vessel from carrying blood

3. It transports nutrients throughout the plant

4. It blocks the vessel, preventing fluid flow

The correct answer is: It blocks the vessel, preventing fluid flow

Tylose serves a critical role within xylem vessels, primarily in the context of plant health and functionality. When considering its function, tylose is a type of parenchyma cell that can invade and fill the lumen of xylem vessels. This process can be especially important when the plant is under stress, such as during disease or injury. By blocking the vessel, tylose acts as a protective mechanism to prevent further fluid loss and to reduce the spread of pathogens or blockages that could compromise the overall vascular system. In this sense, tylose is particularly advantageous for maintaining the integrity of the plant's water transport system. While it doesn't absorb water or directly transport nutrients, its function is crucial in managing water flow and protecting the plant from further issues that could arise from open and functioning vessels. Thus, the blockage created by tylose is a key feature for plant survival and resilience in adverse conditions.