The net amount of carbon in the atmosphere between 1750 and 2012 .

From 280 ppm to 393 ppm.

Explanation:

In 1750, the amount of carbondioxide in the atmosphere was 280 ppm which increases by 393 ppm in 2012. This is because of the pollution occurs due to industrialization and number of vehicles increased in the world. More carbondioxide gas is released due to the smoke produced from burning of fossil fuels in industries and vehicles. So we can say that pollution is the main reason for increasing carbondioxide concentration in the atmosphere.

each of the 46 original chromosomes splits into two daughter chromosomes, so there are two sets of 46 daughter chromosomes that end up in each cell. human cells have 46 chromosomes. each chromosome consists of a pair of identical chromatids attached together by a structure called a centromere.