Iron is concentrated in earth’s core because of the a. movement of materials due to heating in earth’s protoplanetary phase. b. sequence of accretion of material during earth’s formation. c. radioactive decay of isotopes in earth’s core to produce iron. d. penetration of iron meteorites to earth’s core when earth was smaller than it is now.

The answer is A. During the formation of earth, the friction as elements collided into a mass caused heating, so earth was them constituted majorly of molten lava. The heavier elements like nickel and iron were submerged to the core. This is because, since they are among the heaviest elements, the effect of gravity on them was the greatest.

you are certainly talking about this picture:

a: is the label of the white square, it is showing the  replication fork, formed by helicase (d) ==> so it is the site of dna separation and replication 

b: is a new dna brand that is following directly the replication fork, so it is continuous ==> built continuously from 5' to 3

c: dna polymerase cannot replicate dna on its own, it needs the of their proteins, and one of them plays the role of a clamp which fixes  the dna with the dna template and increases  the processivity of the enzyme. ==>   stops polymerase from falling off the  template.

d: is the enzyme responsible for forming the replication fork (helicase) ==> unwinds and separates dna into two strands

e: is the delayed strand, it is built  in the opposite sense of the helicase, so dna will be built in fragments ==> built  fragments from 5' to 3 joins

and finally f: is the enzyme that builds  the new dna strand (dna polymerase) ==>   adds nucleotides to make a new dna helix.

credit: gradman555p98x9p

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explanation:

okay now i don't know this but for the pints nothing else to say bye