Nitrate (NO₃^-) Must Be Reduced to the Level of Ammonia

question 99

Multiple Choice

Nitrate (NO₃^-) must be reduced to the level of ammonia (NH₃) in leaves to be assimilated into amino acids. Which statement best describes the transport of nitrate and amino acids in plants?

• A) Nitrate enters the phloem in the roots and is transported to the leaves. Amino acids are transported to the rest of the plant by the phloem.
• B) Nitrate enters the xylem in roots by an entirely apoplastic route and is transported to the leaves. Amino acids are transported in the phloem.
• C) Nitrate enters the xylem in roots by a pathway that includes its transport across at least one plasma membrane and is transported to the leaves. Amino acids are transported in the phloem.
• D) Nitrate enters the xylem in roots by a pathway that includes its transport across at least one plasma membrane and is transported to the leaves. Amino acids are transported in the xylem.
• E) The nitrate concentration in phloem sap would be higher than that in xylem sap.

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Definitions:

Behavior Modification

A method of therapy rooted in operant conditioning principles, which aims to substitute negative behaviors with positive ones using either rewards or penalties.

Classical Conditioning

The procedure of learning through continual pairing of two stimuli; a behavior that initially results from the second stimulus later results from only the first stimulus.

Instinctive Drift

The inclination of an animal to return to innate behaviors that disrupt a learned reaction.

Extinction

The gradual weakening and eventual disappearance of a learned response.