The four bases in DNA are adenine, cytosine, guanine, and thymine.
<span>These four are divided into two groups. The pyrimidines, the single-ring nitrogenous bases, is where thymine and cytosine is included. The purines, the double-ring nitrogenous bases, includes adenine and guanine. </span>
<span>Cytosine will only bond with guanine; they form three hydrogen bonds. Adenine will only bond with thymine forming two hydrogen bonds.</span>
A.<span> Air pollution............................</span>
The answer is C
Friction between the blowing air and the water drags the water along and create waves
<span>Around 2.4 billion years ago, the first photosynthetic organisms appeared and used inorganic matter like carbon dioxide and water to produce glucose, with oxygen released in the atmosphere. Because of this, oxygen levels rose; this is called the <em>Great Oxygenation Event</em><span><em>.</em> Through time, photosynthetic organisms evolved to live in land (now as plants). As concentrations of oxygen in the atmosphere became higher, marine animals evolved to utilize oxygen readily available from the atmosphere (rather dissolved in water) hence the evolution of marine animals to land animals capable of respiration in land. </span></span>