5) At peak levels of muscle exertion the mitochondria can supply A) only about o
ID: 3479099 • Letter: 5
Question
5) At peak levels of muscle exertion the mitochondria can supply A) only about one-third of the energy required by the muscle. B) all of the energy required by the muscle. C) only about 10 percent of the energy required by the muscle. D) 80 percent of the energy required by the muscle. E) more than half of the energy required by the muscle. 6) When a skeletal muscle fiber contracts A) the zones of overlap get larger. B) the width of the A band remains constant. C) the H bands and I bands get smaller D) the Z lines get closer together E) all of the above 24. In the reaction catab the substrates and endergonic react t are some cellular activities that depend on energy lied by ATP?Explanation / Answer
5. At high levels of muscle activity, the amount of ATP required by the muscle cell is enormous. Although the rate of flow of blood is not altered, the rate of diffusion of oxygen is not fast. The mitochondria can only supply 1/3rd of the required ATP. The rest of the ATP required is supplied by anaerobic glycolysis.
Option A.
6. According to the sliding filament model of muscle contraction, the sarcomeres will shorten in response to nerve impulses. There is sliding of the thick and thin filaments over each other with the filaments, not altering their length. The distance between the Z disc is shortened. The central region of the A zone, the H band with thick filaments, shortens along with shortening of the I band composed of thin filaments. There is no shortening of the A band and its length remains constant. However, A bands of adjacent sarcomeres will move closer to each other. The Z discs approach the thick filaments due to the thin filaments pulling the thick filaments towards the center of the sarcomeres. The zone of overlap of thin and thick filaments in one area will increase due to the inward movement of the thin filaments.
Option E.
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