According to Figure 9

question 626

Multiple Choice

According to Figure 9.6 (The Changing Structure of American Families and Households) , in 2007, the approximate percent of households comprising married couples with children was _____, and the approximate percent of married couples without children was _____.

• A) 15 percent; 45 percent
• B) 22.5 percent; 28.3 percent
• C) 50 percent; 75 percent
• D) 75 percent; 50 percent

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Definitions:

Hyperpolarization

An increase in a cell's membrane potential, making it more negative inside compared to the outside and further from the threshold that causes action potentials.

Absolute Refractory Period

A period immediately following the stimulation during which a nerve or muscle is unresponsive to further stimulation.

Second Messenger System

A method of cellular signaling where the signal from a first messenger is transferred to a secondary molecule inside the cell to elicit a physiological change.

Protein Kinase

An enzyme that modifies other proteins by chemically adding phosphate groups to them, thereby altering their function.