No, polar bears does not migrate.
Answer:
Reproduction is important for the survival of all living things. Without a mechanism for reproduction, life would come to an end.
Explanation:
Reproduction is a characteristic of all living systems; because no individual organism lives forever, reproduction is essential to the continuation of every species.
Increasing salinity<span> also increases the </span>density<span> of sea </span>water<span>. Less dense </span>water<span> floats on top of more dense </span>water<span>. Given two layers of </span>water<span> with the same </span>salinity<span>, the warmer </span>water<span> will float on top of the colder </span>water<span>. ... </span>Temperature<span> has a greater </span>effect<span> on the </span>density<span> of </span>water<span> than </span>salinity<span> does</span>
Black death, also known as the bubonic plague was one of the worst pandemics that ever happened, killing around 1/3 of Europe's population. It spread to Europe in the mid 1300's from China.
Black death victims were treated through magic, witchcraft, prayer and other methods. As for the two other options, they used medicine, but not antibiotics and radiation hadn't been discovered yet (it was discovered in the 1900's)
