Explain the differences between fast-twitch and slow-twitch muscle fibers.
What will be an ideal response?
Fast-twitch muscle fibers are usually anaerobic and designed for strength. Their motor units contain many fibers. They provide explosions of energy and are light in color because they have fewer mitochondria, little or no myoglobin, and fewer blood vessels. These tend to fatigue quickly.
Slow-twitch muscle fibers have motor units with fewer muscle fibers. They have stamina and are useful in endurance activities. The energy is produced aerobically. They have many mitochondria and are dark in color because they contain myoglobin. These have a high resistance to fatigue due to their reserve of glycogen and fat.
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The fertilized egg is totipotent, whereas the cells from the inner cell mass, called embryonic stem cells, are pluripotent. Only the embryonic stem cells can give rise to the entire organism
A. true B. false
Identify the structure of the neuron marked B
a. axon terminal b. cell body c. axon d. glial cell e. dendrites
Which of the following is correct about
melatonin?
a. it protects against certain cancers b. it encourages the growth of certain cancers c. it causes a decline in body temperature d. all of these (a through c) are correct about melatonin e. one of these (a through c) is incorrect about melatonin
The two most closely related groups of fungi are the:
A) basidiomycetes and ascomycetes. B) basidiomycetes and zygomycetes. C) ascomycetes and zygomycetes. D) zygomycetes and chytrids.