Which of the Following Statements Is False Concerning the Xylem

question 102

Multiple Choice

Which of the following statements is false concerning the xylem?

• A) Xylem tracheids and vessels fulfill their vital function only after their death.
• B) The cell walls of the tracheids are greatly strengthened with lignin and cellulose fibrils forming thickened rings or spirals.
• C) Water molecules are transpired from the cells of the leaves, and replaced by water molecules in the xylem pulled up from the roots due to the cohesion of water molecules.
• D) Movement of materials is by mass flow; solutes in xylem sap move due to a positive turgor pressure gradient from source to sink.
• E) In the morning, sap in the xylem begins to move first in the twigs of the upper portion of the tree, and later in the lower trunk.

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Definitions:

Classical Conditioning

A learning process that occurs through associations between an environmental stimulus and a naturally occurring stimulus.

Negative Reinforcement

Increasing behaviors by stopping or reducing negative stimuli. A negative reinforcer is any stimulus that, when removed after a response, strengthens the response. (Note: negative reinforcement is not punishment.)

Latent Learning

Learning that occurs but is not apparent until there is an incentive to demonstrate it.

Operant Conditioning

A method of learning that occurs through rewards and punishments for behavior, encouraging the occurrence of desired behaviors.