Question 1

Which represents a similarity between fast- and slow-twitch muscle fibers?

Accepted Answer

Both fast- and slow-twitch muscle fibers have neuromuscular junctions, which are the sites where motor neurons connect to muscle fibers to transmit signals for muscle contraction.

Question 2

The three systems by which muscles obtain ATP

Accepted Answer

The three systems for ATP production in muscles are the phosphagen system, glycolysis, and oxidative phosphorylation. These systems differ in the capacity and rate at which they produce ATP, with the phosphagen system producing ATP quickly but with limited capacity, glycolysis producing moderate amounts of ATP but at a lower rate, and oxidative phosphorylation producing large amounts of ATP but at a slower rate. Therefore, choice A is the best answer.

Question 3

In the first 15 minutes of a 10K run,the major energy source of the runner's leg muscles is

Accepted Answer

The answer of In the first 15 minutes of a...

Question 4

Which is not one of the systems that supplies muscles with the ATP needed for contraction?

Accepted Answer

Gluconeogenesis is a metabolic pathway that produces glucose from non-carbohydrate sources, such as amino acids, and is not directly involved in supplying ATP for muscle contraction. The other systems listed, immediate, glycolytic, and oxidative, all play a role in providing ATP for muscle contraction. Option E, "both a and c," is incorrect as option A, the immediate system, is a valid system involved in ATP production for muscle contraction.

Question 5

Migrating birds often cross the Gulf of Mexico in a single flight,and their flight muscles demand extreme endurance.An examination of the muscles used to perform this activity would show that they

Accepted Answer

Muscles that demand endurance require a consistent supply of oxygen and fuel. Therefore, they are typically well-supplied with blood vessels. This would be especially crucial for the flight muscles of migrating birds, which need to cover long distances without rest.

Question 6

Compared to the legs of sedentary people,the legs of cross-country skiers and long-distance runners are likely to have

Accepted Answer

Cross-country skiers and long-distance runners rely heavily on endurance, which is best supported by slow-twitch muscles fibers. Therefore, their legs are likely to have more slow-twitch fibers than the legs of sedentary people.

Question 7

Which statement about slow-twitch and fast-twitch muscles is true?

Accepted Answer

Slow-twitch and fast-twitch muscles express different genes coding for their myosin molecules. Slow-twitch muscles contain more myosin with a slow ATPase activity, while fast-twitch muscles contain more myosin with a fast ATPase activity. This difference in myosin expression and activity contributes to the different functional properties of these two muscle types. The other choices are incorrect.

Question 8

If the slow-twitch muscle fibers of a marathon runner,weight lifter,and triathlon competitor (5K run,1K swim,10K bicycle ride)were compared,which would represent the correct order of the percentage of slow-twitch muscle fibers observed in their bodies (from the athlete with the highest percentage to the athlete with the lowest)?

Accepted Answer

Marathon runners rely heavily on slow-twitch muscle fibers for endurance, so they would have the highest percentage. Triathletes also need endurance for their multiple events, so they would have a high percentage as well. Weight lifters, on the other hand, rely more on fast-twitch muscle fibers for short bursts of intense activity, so they would have a lower percentage of slow-twitch fibers.

Question 9

Wild turkeys have breast muscles that are capable of explosively fast flight,but only for short distances.These muscles

Accepted Answer

The fact that wild turkeys have breast muscles capable of explosively fast flight, but only for short distances, suggests that these muscles are composed of fast-twitch muscle fibers. Fast-twitch fibers are specialized for rapid, high-force contractions over short periods of time, and are therefore well-suited for explosive bursts of activity, like short-distance flight.

Question 10

Salmon returning to spawn in their native stream require extreme endurance for the journey.An examination of the muscles used to perform this activity would show that they

Accepted Answer

Myoglobin is a protein found in muscles that binds to oxygen and helps muscles use oxygen efficiently. Salmon need a lot of oxygen for their extensive journey and myoglobin plays a crucial role in delivering that oxygen, making option E the most likely choice.

Question 11

Which is a difference between fast-twitch fibers and slow-twitch fibers?

Accepted Answer

Fast-twitch fibers are more suited for quick, powerful movements such as sprinting, while slow-twitch fibers are more suited for endurance activities such as marathon running. Therefore, fast-twitch fibers are more common in the leg muscles of champion sprinters, while slow-twitch fibers are more common in the leg muscles of marathon runners.

Question 12

Fast-twitch fibers

Accepted Answer

All of the above statements are true. Fast-twitch fibers are also called white muscle because they have fewer blood vessels and less myoglobin than slow-twitch fibers, which gives them a lighter color. They fatigue rapidly because they rely heavily on anaerobic metabolism to generate energy, which can create lactic acid build-up and reduce their ability to contract. They also have fewer mitochondria per cell compared to slow-twitch fibers, which rely on aerobic metabolism to sustain contractions. Therefore, fast-twitch fibers are also called glycolytic muscle because they rely primarily on glycolysis to produce ATP.

Question 13

A characteristic of the glycolytic system for supplying ATP to muscle fibers is

Accepted Answer

C  E  A) Glycolysis is less efficient than aerobic respiration because it produces only 2 ATP molecules per glucose molecule compared to up to 38 ATP in aerobic respiration.  C) Glycolysis can rapidly produce ATP, which is crucial for short bursts of activity.  E) Glycolysis can occur without oxygen, making it an anaerobic process.

Question 14

Slow-twitch fibers

Accepted Answer

Slow-twitch fibers are also called oxidative muscle because they rely heavily on aerobic metabolism, which requires oxygen. They are also called red muscle due to their high myoglobin content, which gives them a red color. Slow-twitch fibers are well supplied with mitochondria, which are responsible for generating energy through aerobic metabolism. Therefore, all the given options are correct.

Question 15

Refer to the graph below showing the capacity of three systems that provide ATP for muscle contraction in humans.Based on the diagram,which statement is true?

Accepted Answer

Curve B represents the system of anaerobic glycolysis, which can provide ATP within seconds but is not efficient for sustained activity. Curve A represents the immediate system of ATP and creatine phosphate, while curve C represents the system of oxidative phosphorylation, which uses preformed ATP and creates new ATP from the breakdown of carbohydrates, fats, and proteins. None of the statements are completely true for A, C, or D, but B is the best choice as it accurately describes the system represented by curve B. Curve C also enables fast-twitch fibers to generate force quickly, but this is not enough to make it the correct answer.

Question 16

The glycolytic system by which muscles obtain ATP

Accepted Answer

The answer of The glycolytic system by which muscles obtain...

Question 17

Shot-putters competing in track and field events need short,intense bursts of energy,but they tend to be quickly fatigued by the activity.An examination of the muscles used in this sport would show that they

Accepted Answer

Shot-putters require short, intense bursts of energy to throw the shot, which requires the muscles to develop tension quickly. This means that the muscles must contract rapidly and generate force, which can lead to quick fatigue due to the buildup of lactic acid. While the other options may be true for some muscle types, the ability to generate tension quickly is the most important factor for shot-putters.

Question 18

Fast-twitch skeletal muscle fibers,called white muscle,are characterized by

Accepted Answer

Fast-twitch skeletal muscle fibers, also known as white muscle, are characterized by the rapid development of high tension. This is due to their ability to contract quickly and forcefully, making them well-suited for activities that require explosive power, such as sprinting or weightlifting. While white muscle fibers do not have a high concentration of myoglobin or abundant mitochondria, they do have a lower oxygen requirement than slow-twitch fibers, enabling them to function anaerobically for shorter periods of time.

Question 19

Bricklayers occasionally need to carry stacks of bricks from their truck to the work site;this is a heavy load,but it is only carried a short distance.An examination of the muscles used to perform this work would show that they

Accepted Answer

The answer of Bricklayers occasionally need to carry stacks of...

Question 20

Which statement about fast-twitch and slow-twitch fibers is false?

Accepted Answer

Fast-twitch fibers are actually known for their quick fatigue, not slow fatigue. Slow-twitch fibers are the ones that are fatigue-resistant.

Quiz 33: Muscle and Movement