Q: Tropomyosin is a type of what, that winds around the chains of the actin filament and covers the myosin-binding sites to prevent actin from binding to myosin? Read this paragraph and choose the correct option from the provided answers: Tropomyosin is a protein that winds around the chains of the actin filament and covers the myosin-binding sites to prevent actin from binding to myosin. Tropomyosin binds to troponin to form a troponin-tropomyosin complex. The troponintropomyosin complex prevents the myosin "heads" from binding to the active sites on the actin microfilaments. Troponin also has a binding site for Ca++ ions. To initiate muscle contraction, tropomyosin has to expose the myosin-binding site on an actin filament to allow cross-bridge formation between the actin and myosin microfilaments. The first step in the process of contraction is for Ca++ to bind to troponin so that tropomyosin can slide away from the binding sites on the actin strands. This allows the myosin heads to bind to these exposed binding sites and form cross-bridges. The thin filaments are then pulled by the myosin heads to slide past the thick filaments toward the center of the sarcomere. But each head can only pull a very short distance before it has reached its limit and must be "re-cocked" before it can pull again, a step that requires ATP. Choices: - enzyme - bacteria - amine - protein A:
protein

Q: A globe is the best way to make a map of what? Read this paragraph and choose the correct option from the provided answers: Earth is a sphere and so is a globe. A globe is the best way to make a map of the whole Earth. Because both the planet and a globe have curved surfaces, the sizes and shapes of countries are not distorted. Distances are true to scale. ( Figure below ). Choices: - a continent - solar system - a city - whole earth A:
whole earth

Q: In physics, _______ is defined as the average kinetic energy of the particles in an object? Read this paragraph and choose the correct option from the provided answers: No doubt you already have a good idea of what temperature is. You might define it as how hot or cold something feels. In physics, temperature is defined as the average kinetic energy of the particles in an object. When particles move more quickly, temperature is higher and an object feels warmer. When particles move more slowly, temperature is lower and an object feels cooler. Choices: - climate - potential energy - heat - temperature A:
temperature