Why Are Slow-Twitch Muscles Dark

question 29

Multiple Choice

Why are slow-twitch muscles dark?

• A) They have many more myofibrils per motor unit than fast-twitch fibers.
• B) They are designed for strength and explosions of energy.
• C) They need less blood than fast-twitch fibers.
• D) They contain myoglobin.
• E) They have fewer mitochondria.

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Definitions:

Reactivity

The inclination of a material to participate in chemical changes, alone or in combination with other elements, leading to the liberation of energy.

Chlorine

A highly reactive, greenish-yellow gaseous element used in water purification and the production of numerous chemicals.

Aluminum Chloride

A chemical compound with the formula AlCl3, widely used in the chemical industry as a catalyst and as a component in a variety of chemical reactions.

O,p-director

Substituents in aromatic substitution reactions that direct incoming substituents to the ortho and para positions relative to themselves.