* not completed

. Fast glycolytic muscle fibers can shorten more rapidly than slow oxidative muscle fibers because fast glycolytic fibers have

more myosin. correct incorrect

a myosin that works faster than the myosin found in slow oxidative fibers. correct incorrect

more mitochondria. correct incorrect

more glycolytic enzymes. correct incorrect

* not completed

. A muscle that lifts 40 kg at a rate of 0.5 m/s would generate power at a rate of

0.0125 watts. correct incorrect

20 watts. correct incorrect

80 watts. correct incorrect

200 watts. correct incorrect

* not completed

. In humans, endurance training typically causes _______ muscle fibers to be converted to _______ muscle fibers.

fast glycolytic; fast oxidative correct incorrect

fast oxidative; fast glycolytic correct incorrect

slow oxidative; fast glycolytic correct incorrect

slow oxidative; fast oxidative correct incorrect

* not completed

. Endurance exercise leads to increased transcription of genes encoding

faster myosin isoforms, glycolytic enzymes, and sarcoplasmic reticulum proteins. correct incorrect

faster myosin isoforms, mitochondrial proteins, and sarcoplasmic reticulum proteins. correct incorrect

slower myosin isoforms, mitochondrial proteins, and angiogenic signals. correct incorrect

slower myosin isoforms, creatine phosphate, and angiogenic signals. correct incorrect

* not completed

. Which effect on skeletal muscle would result from several weeks of endurance exercise training, such as long-distance running?

An increase in enzymes needed for lipid oxidation correct incorrect

An increase in muscle cell cross-sectional area correct incorrect

An increase in myosin Type IIb correct incorrect

An increase in glycolytic enzyme concentrations correct incorrect

* not completed

. The increase in mitochondrial number that occurs with endurance training increases the

rate at which ATP is used in the muscle. correct incorrect

rate at which ATP can be supplied by steady-state aerobic pathways. correct incorrect

rate of calcium release and reuptake in the muscle. correct incorrect

maximum shortening velocity of the muscle. correct incorrect

* not completed

. Resistance exercise generates signals in muscle cells. Plausible signals include

stretch of cell membranes and the cytoskeleton. correct incorrect

high partial pressures of oxygen. correct incorrect

high ATP. correct incorrect

low calcium. correct incorrect

* not completed

. Resistance training does not typically result in an increase in

muscle fiber diameter. correct incorrect

maximum isometric force. correct incorrect

mitochondrial number. correct incorrect

myosin mRNA levels. correct incorrect

* not completed

. Increases in workload can cause cardiac myocytes to

increase in both cross-sectional area and length. correct incorrect

increase in cross-sectional area and decrease in length. correct incorrect

decrease in cross-sectional area and increase in length. correct incorrect

decrease in both cross-sectional area and length. correct incorrect

* not completed

. When researchers compared the hearts of unfed Burmese pythons with hearts of pythons that had eaten a large meal, they observed that fed pythons had larger hearts, higher concentrations of myosin mRNA, and lower concentrations of DNA per gram of heart muscle. These results indicate that the

heart cells of the fed animals could not synthesize as much protein. correct incorrect

fed pythons had more heart cells. correct incorrect

fed pythons had larger heart cells. correct incorrect

fed pythons had fewer heart cells. correct incorrect

* not completed

. Muscle atrophy takes place whenever protein

synthesis in muscle stops. correct incorrect

degradation in muscle stops. correct incorrect

degradation takes place in muscle. correct incorrect

degradation exceeds protein synthesis. correct incorrect

* not completed

. During spaceflight, leg muscles atrophy more than arm muscles do. This may occur because

leg muscles experience more training than arm muscles during daily activity in normal gravity. correct incorrect

arm muscles lack the atrophy-promoting genes that are expressed in leg muscles. correct incorrect

arm muscles lack the gene for myostatin, so they maintain higher muscle masses. correct incorrect

leg muscles contain more protein, so the body catabolizes them first to maintain protein balance. correct incorrect

* not completed

. The muscle cells of patients who have been paralyzed for a substantial period tend to

consist of mostly slow oxidative fibers. correct incorrect

consist of mostly fast glycolytic fibers. correct incorrect

have a very slow unloaded shortening velocity. correct incorrect

be very efficient at using ATP. correct incorrect

* not completed

. Analysis of the athletic performance of aging athletes indicates that

muscle power increases with age, but endurance declines with age. correct incorrect

muscle endurance increases with age, but power declines with age. correct incorrect

both power and endurance performance decline with age, but endurance declines sooner. correct incorrect

both power and endurance performance decline with age, but power declines sooner. correct incorrect

* not completed

. When a motor neuron dies, the muscle fibers innervated by that motor neuron

are reinnervated by other motor neurons. correct incorrect

die. correct incorrect

are converted into slow-twitch fibers. correct incorrect

cannot contract, but they remain healthy. correct incorrect

* not completed

. Studies of the estivating frog Cyclorana alboguttata indicate that

their muscles are unusually plastic in response to immobilization and starvation. correct incorrect

amino acids are readily liberated from muscle to maintain energy balance during starvation. correct incorrect

high levels of reactive oxygen species are produced during estivation. correct incorrect

large muscles used in jumping are especially resistant to atrophy during estivation. correct incorrect

* not completed

. Which condition would be the most likely to increase expression of myostatin mRNA in a person's left calf muscles?

A whole-body weight-training program correct incorrect

A marathon training program correct incorrect

Immobilization of the right leg in a cast correct incorrect

Immobilization of the left leg in a cast correct incorrect

* not completed

. Animals with myostatin gene mutations (including some dogs and cattle) have increased muscle mass relative to animals with nonmutated myostatin genes. This indicates that myostatin may

increase rates of muscle protein synthesis. correct incorrect

increase its target cell response by serving as an IGF-1 receptor agonist. correct incorrect

trigger pathways that increase rates of protein degradation, in addition to regulating muscle mass by inhibiting protein synthesis. correct incorrect

increase phosphorylation of Akt. correct incorrect

* not completed

. Satellite cells

divide and fuse into existing muscle cells when the cell is shrinking. correct incorrect

differentiate into endothelial cells to form capillaries in response to endurance exercise. correct incorrect

grow larger in response to resistance training and become new muscle cells. correct incorrect

divide and fuse into existing muscle cells to increase the number of nuclei in the muscle cells. correct incorrect

* not completed

. There is currently great scientific interest in identifying genetic polymorphisms underlying different individual responses to exercise training. What polymorphism might one expect to find in a champion distance runner?

A mutation that increases transcription of the mRNA for myostatin correct incorrect

A mutation that increases transcription of mRNA encoding Kreb's cycle enzymes correct incorrect

A mutation that yields a missense reading in the myostatin gene correct incorrect

A mutation that increases transcription of the mRNA for atrophy genes correct incorrect