What is a sieve-tube element?
a. The sugar-conducting cell found in phloem
b. The widened, perforation-containing, water-conducting cell found only in angiosperms
c. The nutrient- and water-absorbing cells found in root hairs
d. The nucleated and organelle-rich support cell found in phloem

Verified step by step guidance

Understand that sieve-tube elements are a type of cell found in the phloem of vascular plants.

Recognize that the primary function of sieve-tube elements is to conduct sugars and other organic nutrients throughout the plant.

Note that sieve-tube elements are unique because they lack a nucleus and most organelles, which allows for efficient transport of nutrients.

Identify that sieve-tube elements are connected end-to-end to form long tubes, facilitating the flow of nutrients.

Remember that sieve-tube elements are associated with companion cells, which help maintain their function and provide metabolic support.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Phloem

Phloem is a type of vascular tissue in plants responsible for the transport of nutrients, particularly sugars, throughout the plant. It consists of various cell types, including sieve-tube elements, companion cells, and phloem fibers. Phloem plays a crucial role in distributing the products of photosynthesis from leaves to other parts of the plant.

Sieve-Tube Elements

Sieve-tube elements are specialized cells in the phloem that facilitate the transport of sugars and other organic nutrients. These cells are elongated and connected end-to-end, forming a continuous tube. They lack a nucleus and most organelles, allowing for efficient flow of sap, and are supported by companion cells that help maintain their function.

Companion Cells

Companion cells are nucleated cells found in the phloem that are closely associated with sieve-tube elements. They play a vital role in maintaining the function and viability of sieve-tube elements by providing metabolic support and facilitating the loading and unloading of sugars into the phloem. Their presence ensures the efficient transport of nutrients throughout the plant.