Fill in the Blank in the Following Paragraph Regarding X-Chromosome

question 49

Short Answer

Fill in the blank in the following paragraph regarding X-chromosome inactivation. Do not use abbreviations.
"The presence of two copies of the X chromosome in females but only one in males poses a potential problem for regulation of gene expression: everything else being equal, the higher copy number of the X-linked genes can lead to an imbalanced overproduction of their products in females compared to males. Organisms have evolved different … mechanisms to solve this problem. In mammals, for example, the almost complete inactivation of one of the X chromosomes provides the solution to the dosage problem."

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Definitions:

Just Noticeable Difference

The minimal change in stimulus intensity required to detect a difference between two stimuli, according to psychophysical research.

Visual Acuity

The sharpness or clarity of vision, often measured by the ability to discern letters or numbers at a given distance according to a standardized chart.

Absolute Threshold

The minimum level of stimulus intensity needed for a stimulus to be perceived or detected at least half the time by an observer.

Perceptual Invariance

The ability to perceive the unchanging properties of objects (shape, size, brightness, color) despite variations in the sensory input.