<span>A prokaryote is a unicellular organism that belongs to either the domain Bacteria or the domain Archaea. Therefore, unlike a eukaryote, the prokaryote lacks in a nucleus and other organelles. The first organisms that appeared about 3.5 billions years ago were prokaryotes. They developed primitive forms of photosynthesis without oxygen as a waste. The first photosynthesizing prokaryotes appeared about 2.7 billion years ago which led to the changes in Earth atmosphere and consequently organisms dependant on oxygen could arise.</span>
Answer :Erwin Chargaff a Biochemist
Explanation:
He formulated the base paring of double helix of DNA. He reasoned that since the percentage of four DNA bases are of this proportions in human;
Adenine=30.9% and Thymine =29.4%;
Guanine=19.9% and Cytosine =19.8%
Then, the amount of adenine will always be equal to thymine,
And the amount of Guanine equals to cytosine based on this percentages of distribution.
(Adenine and Guanine are large, molecule of Purines, while thymine and Cytosine are Pyrimidine)
He concluded (although scientist believed, he did not explicitly stated this) that this should be the base paring patterns in DNA molecule. This is the first Chargaff Rule.
His second rule is that the DNA composition, in the relative amount of the four bases Adenine, Thymine, Cytosine and Guanine varies in proportion from one organisms to another. And this is the basis of molecular diversity.
Answer:
Some folks will undoubtedly confront bigger difficulties than others. Those who live in locations exposed to coastal storms, drought, and sea level rise, as well as people in poverty, elderly individuals, and immigrant populations, may be particularly affected by climate change.
Explanation:
<span>The crust and the upper layer of the mantle together make up a zone of rigid, brittle rock called the lithosphere. </span>
