Refer to the Table Below Showing Observations from Experiments Conducted

question 97

Multiple Choice

Refer to the table below showing observations from experiments conducted on three types of pea plants.One type of pea plant contained a mutation in the gene encoding thioredoxin that resulted in zero production of the protein thioredoxin.Another type contained two mutations: the same thioredoxin mutation as in the previous type and a mutation in the gene encoding the Calvin cycle enzyme phosphoribulokinase (PRK) that did not affect its expression.The third type contained no mutations in either gene and was designated as "wild type." Before the experiments, all plants were kept on a 14-hour light/10-hour dark cycle for several weeks. In conducting the experiments, researchers excised leaves either toward the end of a light cycle or toward the end of a dark cycle.Chloroplasts were then isolated and lysed to release the contents of the stroma, and PRK was assayed to determine its catalytic activity.Which statement about thioredoxin is consistent with these data?

• A) Thioredoxin is an electron carrier protein that participates in the electron transport chain during photophosphorylation.
• B) Thioredoxin is a regulatory molecule, becoming activated via light-induced changes and then activating PRK by shifting it from an inactive to an active conformation.
• C) Thioredoxin is a regulatory molecule, shutting down Calvin cycle reactions by acting as an alternative to NADP⁺ as the final electron acceptor during the light reactions.
• D) Thioredoxin is an enzyme that functions in carbon fixation as an alternative to the Calvin cycle enzyme rubisco.
• E) Thioredoxin is an integral protein component of the thylakoid membrane that ensures that the membrane remains impermeable to protons.

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Definitions:

Bile

A digestive fluid produced by the liver and stored in the gallbladder, essential in the breakdown and absorption of fats.

Teniae Coli

Long, ribbon-like bands of smooth muscle on the surface of the colon, contributing to its segmentation and movement.

Longitudinal Layer

In anatomy, the longitudinal layer refers to muscle fibers oriented lengthwise in an organ, such as those found in the digestive tract, aiding in its contraction and relaxation.

Portal Triad

Branches of the portal vein, hepatic artery, and hepatic duct bound together in the connective tissue that divides the liver into lobules.