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:

Mitochondria

Organelles found in the cytoplasm of eukaryotic cells that produce energy through cellular respiration.

Oxidative Enzymes

Enzymes that catalyze the transfer of electrons from one molecule to another, playing a critical role in cellular respiration and detoxification.

Peroxisome

Membrane-bounded body similar to a lysosome in appearance but often smaller and irregular in shape; contains enzymes that either decompose or synthesize hydrogen peroxide.

Rough ER

A part of the endoplasmic reticulum with ribosomes attached to its surface, involved in protein synthesis.