The difference between an artery and a vein is that arteries are larger, more muscular and more elastic than veins; they carry blood that is under pressure from having been pumped out of the heart; veins are under much less pressure, so they are not as strong
This happens if the object goes somewhere where gravity is stronger, or weaker, such as the Moon. The Moon has less mass than the Earth, so its gravity is less than the Earth's gravity. This means that objects weigh less on the Moon than they do on the Earth. The Moon's gravity is one sixth of the Earth's gravity. Hope this helps!
Fermentation occurs in anaerobic respiration, and produces less energy than in aerobic respiration due to the lack of ETC because oxygen is not present.
Nicotine, once in the brain, will work specifically on nicotinic receptors in the brain. However, there is a common "addiction" pathway in the brain that pretty much all addictive substances go through.
