Question

Slow-twitch muscle fibers:

A) Fatigue very easily.
B) Have a relatively high content of mitochondria.
C) Are designed for speed.
D) Are designed for powerful contractions.
E) Do not require action potentials for activation

Answer 1

Slow-twitch muscle fibers have a high content of mitochondria, which allows them to sustain aerobic activity and resist fatigue, making them important for endurance activities.

Step-by-step explanation:

The question relates to the characteristics of slow-twitch muscle fibers, which are a type of skeletal muscle fiber. Option B) Have a relatively high content of mitochondria is the correct answer.

Slow-twitch muscle fibers are indeed dense with capillaries and rich in myoglobin and mitochondria. This abundance of mitochondria allows slow-twitch fibers to sustain aerobic metabolism and therefore enable them to perform activities that require endurance over long periods, such as distance running or cycling. Unlike fast-twitch fibers, they are not designed for speed or powerful contractions and do not fatigue easily. Additionally, slow-twitch fibers require action potentials for activation, as do all muscle fibers, which disqualifies the other options provided.