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:
Rock
Explanation:
Minerals are inorganic substances that occur naturally in nature and have a
a definite chemical composition and a crystalline structure while rocks may consists of one or many minerals together along with some organic remains due to which it may not look shiny and crystalline from outside.
Here, the two characteristics that enable the reader to identify the object given by grandmother to Emily as rock are –
a) Looks ugly on the outside (shows the presence of organic matter)
b) solid purple color with pretty crystals (crystalline structure inside)
It is not a mineral because it is man made!
Answer:
1. Air warms, becomes less dense, it rises
2. Air cools down, increases density (becomes denser), it sinks
