AP Biology : Understanding Muscle Cells
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Example Question #41 : Understanding Muscle Cells
Which of the following is responsible for the red appearance of some muscles?
They contain large quantities of myoglobin
They have few mitochondria
They are anaerobic
They are fast twitch—fast contraction—muscles
They contain large quantities of myoglobin
Muscle tissue can be divided into red—fast twitch—and white—slow twitch—muscle types. Red muscles have many capillaries, mitochondria, and myoglobin. Red muscles also perform aerobic activity.
Example Question #42 : Understanding Muscle Cells
Which of the following best defines “myofibrils”?
Basic muscle cells
The area between Z lines
Specialized units in skeletal muscle tissue
Chains of myocytes
Chains of myocytes
Myofibrils are the basic units of all muscle tissue that are composed of chains of myocytes. Myocytes contain thin and thick filaments of proteins that organize into sarcomeres.
Example Question #42 : Understanding Muscle Cells
When muscle contraction occurs, calcium ions bond to which of the following structures?
Sarcoplasmic reticulum
Tropomyosin
Troponin
Actin
Myosin
Troponin
The calcium ions bind to troponin, which causes the release of the tropomyosin from actin as a result of the troponin-tropomyosin complex detaching. This makes the binding site on actin available for myosin to attach to. The sarcoplasmic reticulum stores calcium for its quick release to facilitate muscle contraction.
Example Question #43 : Understanding Muscle Cells
During his summer break, John decided to go workout at his local gym. During his training, he began to experience muscle pain in the area of the pectoralis major muscle. Which of the following best describes the muscle fibers of the pectoralis major muscle?
Red muscle fibers
Smooth muscle fibers
Brown muscle fibers
Cardiac muscle fibers
White muscle fibers
White muscle fibers
Skeletal muscle fibers come in 3 types: red (type I), intermediate/pink (type IIA), and white (type IIB). Red muscle fibers produce slow movement and do not fatigue quickly; these muscles mainly utilize oxidative phosphorylation as an energy source. White muscle fibers work the fastest, but also fatigue much more rapidly; these muscles mainly utilize glycolysis as a source of energy. Intermediate muscle fibers consist of both red and white muscle fibers. All muscles contain some degree of intermediate muscle fibers, however the pectoralis major muscle is an example of a muscle group primarily composed of white muscle fibers. Cardiac muscle is found in the heart only, and smooth muscle is involuntary.
Example Question #44 : Understanding Muscle Cells
While playing intense basketball you feel some cramps in your muscles, what is likely the cause of these cramps?
Alcohol fementation
An abundance of oxygen delivery to the muscles
Oxidative phosphorylation
Lactic acid fermentation
Chemiosmotic coupling
Lactic acid fermentation
The correct answer to this question is lactic acid fermentation.
Lactic acid fermentation occurs in human muscle cells when oxygen is not available. Alcohol fermentation only occurs in yeast, fungi, and some bacteria. The other answers are unrelated to cramps and instead just are other concepts of respiration.
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