Answer:
<h2>Source of Light in Universe</h2>
<h3>Although the Sun doesn't light up the other stars, it does provide the daylight here on Earth; and the moon and planets we see are illuminated by that same sunlight. All stars produce light (and other kinds of energy) through nuclear reactions, using the energy stored in the tiny nucleus at the center of atoms.</h3>
Explanation:
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<em><u>THANKS</u></em><em><u>❤</u></em><em><u>❤</u></em></h2>
Scientists developed the time scale by studying rock layers and fossils world wide.
Radioactive dating helped determine the absolute divisions in the time scale. so mass extinction help because there is more to study
By sodium and potassium pump.
The sodium-potassium pump is observed in various cellular membranes. They are fueled by ATP, the pump moves potassium and sodium ions in reverse orientation, each against its concentration gradient. In a single cycle, two potassium ions are imported into the cell, and three sodium ions are extruded out.
These pumps are utilized to produce gradients of sodium and potassium ions. These gradients are used to proliferate electrical signals, which travel along the nerves.
