The appropriate answer is c. global warming. Global warming is an increase in the global temperature caused by the increased use of fossil fuels. Using fossil fuels since the industrial revolution has pumped extra carbon dioxide in the atmosphere than what would actually enter from natural processes. This extra carbon dioxide is increasing the green house effect and causing the temperature to increase.
Answer:
With respect to the composition of DNA, in an analysis it can be found that the proportions of nucleotides are A + C = G + T (option a).
Explanation:
The proportion of nucleotides in a DNA molecule can be established according to the sequence of these nucleotides on both complementary strands, since the purinic bases of one strand are complemented by the pyrimidinic bases of another:
- <em>Adenine is complemented with Thymine A=T</em>
- <em>Guanine is complemented with Cytosine G=C</em>
From this we can deduce that in a DNA molecule with two chains there will be the same amount of adenine and thymine, as well as the same number of guanine with respect to cytosine, so:
<em> A + C = G + T</em>
An example of this would be a known DNA molecule (hypothetical), with 5 molecules of Adenine and 7 molecules of Guanine. In this case there are 5 Thymines, complementary with Adenine, and 7 Cytosines like Guanine:
<em> A + C = G + T</em>
<em> 5 + 7 = 7 + 5</em>
Salmonella is the parasitic worm that can be transferred to humans when eating raw or undercooked fish.
Answer:
Approximately 4.5 billion years ago (The Hadean Eon) .
Explanation:
The Geologic Timescale's "Hadean" era, named for Hades (Hell, well, we weren't feeling very imaginative that day), encompasses the Earth's origins. According to the evidence we currently have, the Earth's surface at that time was mostly made up of lava lakes and molten rock.
How would that appear? The first 500 Ma of Earth's history have left very little stuff behind. You may, however, take a peek at our moon, which similarly went through a lava lake period before freezing. You'll see that it has both dark and bright landscape.
The lighter material is known as highlands and is primarily composed of anorthosite. Anorthose, a kind of plagioclase feldspar, is the main component of the igneous rock known as anorthosite. According to what we know, the Moon too had a lava lake era. Liquid rocks exposed at the surface were cooling and fractionally crystallizing throughout this lengthy period. A certain order of minerals was developing. And these minerals were dividing up according to the density of the melt; less dense minerals, like plagioclase (Anorthose is a plagioclase), floated to the surface in a sort of incandescent crystal slush slurry and formed a sort of lid there. Denser minerals, like olivines, were sinking to the bottom of the lava lake to form cumulates. As the lava lakes cooled, anorthosite piled on top in successive layers, thickening the mass of floating crystals. Large meteor impacts occasionally pierced this anorthosite crust, and part of the thicker (and darker) underlying liquid accumulated in the ensuing craters to produce those roundish dark patches (Maria), which are now filled with basalt.
After the lava lakes froze/crystallized over, such characteristics were maintained since there was no significant tectonic activity on the Moon (except for the local meteor impacts which screw things up a bit).
