How do the structural characteristics of xylem vessel elements and sieve tube elements reflect their respective functions in transport?
Understand the Problem
The question asks how the physical structures of xylem and phloem cells relate to their specific roles in plant transport. It requires an understanding of the different cell types (vessel elements in xylem and sieve tube elements in phloem) and how their structures enable efficient water and nutrient transport throughout the plant.
Answer
Xylem vessel elements are dead cells with thick walls for water transport, while sieve tube elements are living cells with thin walls and sieve plates for sugar transport, supported by companion cells.
Xylem vessel elements are dead cells with thick, lignified walls to provide structural support and prevent collapse under the negative pressure required for water transport. Their end walls are either perforated or absent to facilitate unimpeded water flow. Sieve tube elements are living cells with thin walls, connected end-to-end to form sieve tubes. They have sieve plates with pores that facilitate the transport of sugars and other organic compounds. They rely on companion cells for metabolic support.
Answer for screen readers
Xylem vessel elements are dead cells with thick, lignified walls to provide structural support and prevent collapse under the negative pressure required for water transport. Their end walls are either perforated or absent to facilitate unimpeded water flow. Sieve tube elements are living cells with thin walls, connected end-to-end to form sieve tubes. They have sieve plates with pores that facilitate the transport of sugars and other organic compounds. They rely on companion cells for metabolic support.
More Information
The key difference lies in their structure and cell composition which allows them to carry out their respective transport functions effectively. Xylem is made of dead cells and sieve tubes are living cells.
Tips
A common mistake is confusing the functions of xylem and phloem. Xylem transports water and minerals, while phloem transports sugars. Another mistake is thinking xylem cells are living.
Sources
- Xylem - an overview | ScienceDirect Topics - sciencedirect.com
- 25.4B: Vascular Tissue- Xylem and Phloem - Biology LibreTexts - bio.libretexts.org
- Xylem - Wikipedia - en.wikipedia.org
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