Acid rain can be very harmful, mildly harmful, or not harmful at all. It mainly depends on the density of the rain, and how bad the current air pollution in the area is. Also, it depends on how often the area gets acid rain. The first few times an area gets acid rain, it's nearly harmless. Then, the next few it can be very dangerous, but eventually gets weaker over time. More air polluted areas are more likely to get much more harmful acid rain.
Summary: Acid rain is usually mildly harmful, mostly only harmful to infrastructures.<span />
A Only one variable changed
Cross over is the first way genes are shuffled to give rise to genetic diversity. Cross over takes place in sexual reproduction. The normal way that cross over occurs is chromosomes line up side by side and break off pieces of themselves, then trade those pieces with each other.
If they break the pieces at the same locus in the sequence of base pairs, the result is an exchange of genes called genetic recombination and it ensures that the daughter cells produced have a different genetic makeup from the parent cell and thus diversity occurs.
Answer:
C. H and O
Explanation:
Almost 99% of the human body's mass is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium and phosphorus, in that order.
Element Symbol % in body
Oxygen O 65.0
Coal C 18.5
The human body is composed of 60% water, that is, H2O.
