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Answer: B. Earth's present-day species evolved from older, identical species.
The evolution is the change or modification in the characteristics of a species over genration due to the process of adaptation and natural selection. The statement "Earth's present day species evolved from older, identical species is true about evolution". As, proposed by Darwin evolution is "descent with modification", which means that in a process of evolution species change and give rise to new species over generation. He proposed that newly evolved life forms can be traced back to their common ancestor.
Answer:
Absolute dating(also known as radiometric dating) is based by the measurement of the content of specific radioactive isotopes of which the "half time" is known. ... Relative dating instead allows for identifying the sequential order of geological events one relative to the other.
Explanation:
Answer:
The star is traveling <em>towards</em> the earth.
Explanation:
Space experts arrange stars into groups as per their shading and the composition. This star arrangement framework goes this way: O, B, A, F, G, K, M in which O star is blue and is very hot and <em>M stars are red</em> and the coolest and most basic stars in the Universe.
From the color of the star we can infer that as the star is appearing red it is inferred that the star is an M star and it is traveling towards the earth.
<span>Discovery</span>
The operon model (Lac operon) of the regulation
of gene expression in bacteria was proposed by Jacob and Monod and hey got
noble prize in 1965 in Physiology and Medicine for this discovery.
Definition
<span> “</span><span>Operons are cluster of coregulated bacterial
genes which regulate other genes responsible for protein synthesis” </span>
Explanation
<span>Operons were first studied
in the bacterium E.coli, and they
involve the enzyme of lactose metabolism and tryptophan biosynthesis. </span>
Structure of Operon
<span> </span>Operon is generally
composed of three basic DNA components:
1. Promotor:
<span> It is a nucleotide sequence which is
recognized by RNA polymerase and initiate transcription.</span>
2. Operator:
It is a segment of DNA
that is present between the promotor and other genes to be transcribed. In presence
of repressor, RNA polymerase is physically obstructed and cannot transcribe the
genes. In the absence of repressor, operator is active and start transcription
of other proteins.
3. Structural genes:
<span>These genes are
responsible for synthesis of targeted proteins under the influence of operator<span>. </span></span>
Example of operon model:
<span> In bacteria two operon model have been
extensively studied, these are:</span>
<span> a. Lac Operon, and</span>
<span> b. Tryptophan operon</span>