In About ____ of Fraternal Twin Pairs, One Twin Is

question 4

Multiple Choice

In about ____ of fraternal twin pairs, one twin is a boy and other is a girl.

• A) 10 percent
• B) one third
• C) half
• D) 80 percent

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Definitions:

Visual Sensitivity

The ability of the visual system to detect and respond to small differences or changes in the visual environment.

Opponent-Process Theory

The theory that opposing retinal processes (red-green, blue-yellow, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green.

Ewald Hering

A 19th-century physiologist known for his work on color vision and spatial perception.

Young-Helmholtz Theory

A theory of color vision proposing that the eye contains three types of color receptors, each sensitive to red, green, or blue wavelengths of light.