The troposphere is shallowest or narrowest at the poles, and deepest or thickest at the equator. At the geographic North and South Poles, the troposphere reaches only 4 miles high, while at the equator, it extends nearly 12 miles high.
Answer:
When a muscle cell contracts, the myosin heads each produce a single power stroke.
Explanation:
In rest, attraction strengths between myosin and actin filaments are inhibited by the tropomyosin. When the muscle fiber membrane depolarizes, the action potential caused by this depolarization enters the t-tubules depolarizing the inner portion of the muscle fiber. This activates calcium channels in the T tubules membrane and releases calcium into the sarcolemma. At this point, <em>tropomyosin is obstructing binding sites for myosin on the thin filament</em>. When calcium binds to the troponin C, the troponin T alters the tropomyosin by moving it and then unblocks the binding sites. Myosin heads bind to the uncovered actin-binding sites forming cross-bridges, and while doing it ATP is transformed into ADP and inorganic phosphate which is liberated. Myofilaments slide impulsed by chemical energy collected in myosin heads, <u>producing a power stroke</u>. The power stroke initiates when the myosin cross-bridge binds to actin. As they slide, ADP molecules are released. A new ATP links to myosin heads and breaks the bindings to the actin filament. Then ATP splits into ADP and phosphate, and the energy produced is accumulated in the myosin heads, which starts a new binding cycle to actin. Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.
Answer:
A is the correct answer.
Explanation:
A vulture does eat dead animals but it itself is not classified as a decomposer due to the fact that the remains of most of the animal is still there.
Answer:
Microscopic marine phytoplankton play a critical role in regulating todays carbon cycle yet not enough is known about the process. These tiny organisms consume carbon dioxide from atmosphere and move it to marine sediments in deep ocean. And this process is also known as biological pump<em>.</em>
Explanation:
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