Answer:A. The release of calcium ions causes myosin and actin to attach to each other.
The contraction of skeletal muscles takes place by induction of a nerve impulse, which produces a movement and the interaction of the filaments containing proteins named as actin and myosin. This interaction of filaments is regulated by proteins called tropomyosin and troponin present on the actin filaments. The motor nerve causes the depolarization of the muscle membrane sarcolemma. This triggers the sarcoplasmic reticulum to release calcium ions. This calcium binds to troponin and thus allows the tropomyosine strand on the actin filament to displace so that the part of the actin where myosine head needs to be attached remain uncovered. Binding of the actin myosine filament results in contraction.
Hence, the release of calcium ions causes myosin and actin to attach to each other causes muscle contraction.
Burning paper is a chemical change not a physical one. Hope this helped <span>
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3. Autotrophs produce organic molecules. I think 4 is cellular respiration cannot occur without photosynthesis
<span>B. Rocks go through many stages during their formation</span><span>
Sedimentary rocks together with the igneous rocks and the metamorphic rocks are the three main types of rocks that existed on earth. It is formed or made accordingly into four major ways. First, it is formed by depositing weathered remains of "clastic sedimentary rocks" or other rocks. Second, is through accumulation and the consolidation of sediments, thirdly is by depositing the results of biogenic activity and lastly it is formed through precipitation from solution. Limestone, shale, chalk clay and others are best examples of sedimentary rocks. </span>
Hello There!
Now, i'm not 100% sure on this but i think it is C.
Please let me know if it is correct..i'm sorry if it is wrong.
Hope This Helps You!
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- Hannah ❤
