Answer:
A
Explanation:
Today, the atmosphere holds about 21 per cent oxygen. ... When the first simple organisms appeared in the oceans more than 3.5 billion years ago, the atmosphere was mostly nitrogen, hydrogen, water vapor, and carbon dioxide
Answer:
The correct option is option A
Explanation:
Restriction enzymes are endocleases that cleave DNA fragment (<u>of usually four, five or six nucleotide long</u>) at <u>specific sites to produce blunt or sticky ends</u>. They <u>recognize palindromic sequences of host DNA when cleaving the specific sites</u>. The sequences below (on complementary strands) give an example of a palindromic sequences.
5'-CCC║GGG-3'
3'-GGG║CCC-5'
As can be seen above, when read from 5' to 3', the two sequences are the same despite being on opposing strands. And when cut between the guanine (G) and cytosine (C) (as shown above), it produces a blunt end. But when cut as shown below produces a sticky end.
5'- G║AATTC -3'
3'- CTTAA║G -5'
The explanation above shows options C and D are right while option A is wrong (hence the correct option).
Also, bacteria prevent their own DNA from been digested by restriction enzymes by adding methyl group to their restriction sites <u>which prevents restriction enzymes from recognizing restriction sites of their DNA;</u> this generally makes bacterial DNA to be highly methylated. This explanation makes option B right also.
Explanation:
A cryosphere is just a hydrosphere but it's frozen in some way. glaciers, ice caps, and icebergs are cryospheres (frozen bodies of water).
Part A:
<span>If early conditions of primeval earth had ammonia, methane, hydrogen in its atmosphere, then it is possible that amino acids such as glycine, α-alanine, and β-alanine may have been spontaneously formed from chemical reactions spurred by energy from lightning.</span>
<span>Their hypothesis was that the early conditions of primeval earth favored the spontaneous formation of organic molecules, from inorganic precursors, that may have been the origin of life. This theory is called abiogenesis. </span>
Part B:
<span>Miller Urey put methane, ammonia, hydrogen gases in a glass flask and a pool of water at the bottom of the glass flask. The flask was heated moderately to simulate the hot conditions then. Sparks were also occasionally induced in the flask to mimic lighting. The flask was then cooled slowly to simulate cooling of earth over time.After one day, they found the presence of some amino acids (glycine, α-alanine and β-alanine) was discovered in the water in the flask</span>
