A line segment is a line that has two points on both ends. A point is just as it says, a point that shows a coordinate within a geometric figure. A ray on the other hand is a line with one point on one end and an arrow on the other. A vertical line with an arrow at each end then is a line. The arrow shows that the line extends further.
The answer is C.
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.
Orbital period is the <span> time taken for a given object to make one complete </span>orbit around another object. Mercury orbits the Sun in 88 days. Therefore, Mercury's orbital period is calculated by (88/365.25) or .241 Earth years. Hope this answers the question.
A metamorphic rock is a type of rock which has been changed by extreme heat and pressure. so must be option D
Answer:
The Sun
Explanation:
it is essential to doing photosynthesis
