What was Rudolf Virchow’s contribution to the cell theory? He concluded that all cells come from preexisting cells.
He concluded that cells are the basic units of structure and function of all living things.
He concluded that all organisms are composed of cells.
He concluded that all cells are similar in composition and metabolic activities.

He concluded that all cells come from preexisting cells.

Explanation:

Rudolf Virchow was a German scientist experienced in many fields, including medicine, biology, anthropology, and prehistory. He is especially noted for his contribution to the cell theory. He discovered that all cells come from preexisting cells, which made it clear that diseases develop at the cellular level. This means that Virchow was the one to discover that cancer cells originate from healthy cells. All of this allowed scientists to diagnose diseases more accurately and efficiently.

because they want 2 and yea

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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