Answer:
A portion of an aquifer that contains rock material that does not allow water to penetrate; often forms the base of unconfined aquifers and the boundaries for confined aquifers.
Exactly what the person above said!
Answer:
The basic unit of life is a cell
Answer:
Scientist count the world humans population with an organization called The United Nations Population Division (UNPD),
Explanation:
Which keeps track of the world population, projects that the world's human population will hit 7 billion on Halloween Day 2011. Admittedly, that is just an estimate: There's no way to know exactly how many people are alive at any given moment, and the true date that humanity's ranks will surpass 7 billion could come in the weeks or months before or after Oct. 31. Nonetheless, the UN's guess is the best there is.
