How is active transport different from passive transport? A Both active and passive transport occur within plant cells, but only active transport occurs within animal cells.
B. Passive transport uses energy to move materials across a cell membrane against a concentration gradient, while active transport moves materials across a cell membrane in the direction of a concentration gradient, without using energy.
C. Active transport uses energy to move materials across a cell membrane against a concentration gradient, while passive transport moves materials across a cell membrane in the direction of a concentration gradient, without using energy.
D. Both active and passive transport occur within animal cells, but only active transport occurs within plant cells.​

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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when a reversible reaction is occurring in both directions at the same rate; the products and reactants do not change in concentration. a chemical reaction where the compound is broken into its constituent parts.