Glucose (C₆H₁₂O₆) Can Exist as Both an Open-Chain Form and a Closed-Ring

question 52

Multiple Choice

Glucose (C₆H₁₂O₆) can exist as both an open-chain form and a closed-ring form. Before 1900, glucose was only thought to occur as an open chain. Now we know that over 99 percent of the time, glucose occurs in the closed-ring form. What possible difference between these forms would give chemists a clue that the open-chain form was not present?

• A) Open-chain molecules can form polymers and glucose does not.
• B) Only open-chain forms can undergo condensation, which does not occur with glucose.
• C) An open chain presents ends with functional groups (in this case aldehyde), and glucose failed to undergo typical aldehyde reactions; a phenomenon that could be explained by having no end functional group in a ring structure.
• D) Because glucose is solid at room temperature, it must have saturated hydrocarbon chains.
• E) Glucose could not be "denatured" so it must be a tight chain.

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Definitions:

Systematic Desensitization

A therapeutic technique used to reduce anxiety by gradually exposing the patient to the feared object or situation.

Aversive Conditioning

A method of behavioral training in which an unwanted behavior is associated with discomfort in order to discourage that behavior.

Transference

The process in psychotherapy where patients project feelings and attitudes from a past relationship onto the therapist.

Counterconditioning

A behavior therapy technique involving the conditioning of an undesirable behavior or response to a stimulus into a desired behavior by association of positive actions with the stimulus.