The phenomenon is called an equinox. More specifically when it is September it is called the autumnal equinox ,and when it is March it is called the vernal equinox. Hope this helped!
Answer: hydrogen
Explanation:
Two elements make up the overwhelming majority of the sun's matter, by mass: hydrogen (about 70 percent) and helium (about 28 percent).
Answer: B
Explanation: the sun is made of gas, which doesn't all spin together at the same speed like a solid rock would.
Answer:
binding of the hormone molecule with its receptor of the cell.
Explanation:
Hormones are chemical messengers secreted or released by endocrine glands to effect a response in another location called target location. Hormones are proteinous molecules and like every other protein, its function is determined by its shape.
Hormones function or effect their changes by binding to the receptor of the target cell. The hormone recognizes and will only bind to its own receptor molecule on its target cell on order to bring about any change. This defines the specificity of the hormone.
Triggering of the muscle action potential occurs after Ach binds to chemically gated channels in the motor end plate membrane. Acetylcholine (Ach) is a neurotransmitter produced by nerve cells.
An action potential is an electrical signal that travels along the cell membrane as a wave.
This action potential (muscle action potential) drives the contraction of muscle fibers.
When the action potential reaches the neuromuscular junction (i.e., the motor end-plate), acetylcholine (Ach) is released into the synaptic cleft.
Subsequently, Ach can bind and open specific channels localized on the surface of the muscle cells, thereby depolarizing them and triggering muscle contraction.
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