Why are slow-twitch muscle fibers more resistant to fatigue than are fast-twitch fibers?
What will be an ideal response?
Slow-twitch muscle fibers have abundant myoglobin to promote diffusion of oxygen through the tissue, numerous mitochondria to use the oxygen in aerobic respiration, and a blood supply that delivers a continued stream of glucose. Fast-twitch fibers have reserves of creatine phosphate and glycogen available for glycolysis that provide them with a source of rapidly available ATP, but many fewer mitochondria, and little myoglobin. Thus once their energy stores are exhausted, they cannot generate a continuous supply of ATP by aerobic respiration, which is much more efficient than glycolysis alone.
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Describe amplification of hormone action
What will be an ideal response?
Most tunicate adults are
a. herbivores. b. photoautotrophs. c. carnivores. d. scavengers. e. filter feeders
It is a fact that enzymes are highly specific and will only catalyze one or a few reactions. Can you think of a benefit
that is derived from such specificity? (i.e., What would happen if most biochemical reactions were catalyzed by the same enzyme?) What will be an ideal response?
A dog breeder wishes to develop a breed that does not bark. She starts with a diverse mixture of dogs. Generation after generation, she allows only the quietest dogs to breed. After 30 years of work she has a new breed of dog with interesting traits, but
on average, the dogs still bark at about the same rate as other dog breeds. Which of the following would be a logical explanation for her failure? A) There is a great deal of variation for the trait (barking). B) The tendency to bark is not a heritable trait. C) The selection was artificial, not natural, so it did not produce evolutionary change. D) Quiet dogs have fewer pups than barkers.