Question

What drives the flow of water through the xylem? Question 4 options: passive transport by the endodermis active transport by tracheid and vessel elements the evaporation of water from the leaves the number of companion cells in the phloem

Answer 1

Xylem

Explanation:

The flow of water through the xylem is driven by the evaporation of water from the leaves

• The xylem of a plant is the system of tubes and transport cells that circulates water and dissolved minerals
• Water flows more efficiently through some parts of the plant than others
• Water absorbed by roots must cross several cell layers before entering the specialized water transport tissue referred to as xylem
• These cell layers act as a filtration system in the root and have a much greater resistance to water flow than the xylem, where transport occurs in open tubes
• Once in the xylem tissue, water moves easily over long distances in these open tubes
• There are two kinds of conducting elements (i.e., transport tubes) found in the xylem: 1) tracheids and 2) vessels
• Tracheids are smaller than vessels in both diameter and length, and taper at each end, vessels consist of individual cells or vessel elements stacked end-to-end to form continuous open tubes
• Water movement is passively driven by pressure and chemical potential gradients
• The bulk of water absorbed and transported through plants is moved by negative pressure generated by the evaporation of water from the leaves (transpiration)