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:
75years
Explanation:
Let the Father's age be represented by 2x
Let the Son's age be represented by x
Five years ago;
Man's age will be = 2x - 5
Son's age will be = x - 5
If the ratio of their ages five years ago was 9:4, then;
2x - 5/x-5 = 9/4
4(2x - 5) = 9(x - 5)
8x - 20 = 9x - 45
- Collect like terms
-20 + 45 = 9x - 8x
25 = x
Hence, the son's age = 25 years
If x = 25, the father's age (2x) will be 2 × 25 = 50years
The sum of their ages will be = 25years + 50years = 75years
B. a volcano that erupts in blasts of the pyroclastic matter. D. would be wrong because the shield volcano can have explosive eruptions but they are generally quiet
Answer:
Fourth and Fifth month
Explanation:
The fourth and fifth months formed the major part of the second trimester, and it is characterized by the growth of the brain and central nervous system which shows more alertness and developed faster in a way that appears similar to that of a new baby.
Also, this fourth and fifth month is characterized by growth in other parts of the unborn baby such as an increase in heartbeat, fingernails, hair, eyelashes, and toenails.
