Answer:
The ability of caffeine to inhibit adenosine receptors, plays a very important role in heightened alertness and sleeplessness.
Explanation:
"<em><u>Caffeine</u></em>" (<em>1,3,7-trimethylxanthine</em>) is an alkaloid obtained from plants. It has a chemical formula of C8H10N4O2.
Caffeine is generally <em>hydrophillic</em> but sufficiently <em>lipophilic</em> to pass through all biological membranes and readily cross the blood-brain barrier.
Therefore can bind with the adenosine receptors. Due to the blocking of adenosine inhibitory effects through its receptors held by paraxanthine and caffeine, it indirectly affects the release of <u>norepinephrine, dopamine, acetylcholine, serotonin, glutamate</u> e.t.c.
The release of the above-mentioned hormones have a great impact on the heightened alertness of the body, especially <em>dopamine</em> and <em>serotonin</em>.
Answer: A penumbral lunar eclipse occurs when the Sun, Earth, and the Moon are imperfectly aligned.
Explanation: During this occurance the Earth comes between the Sun and moon and blocks the sunlight from falling on the moon.
You would weigh less on Mars than on Earth because there's less gravity on Mars
