Mention the biochemical role of folic acid in preventing folic acid deficiency anaemia?

Folate deficiency anemia. Treatment involves eating a healthy diet and taking folic acid supplements as prescribed by your doctor. In most cases, folic acid supplements are taken orally. It usually takes a month or longer to correct folate deficiency anemia. If you're someone who can't absorb folate easily, you may need to take folic acid supplements for life.

In the form of a series of tetrahydrofolate compounds, folate derivatives are substrates in a number of single-carbon-transfer reactions, and also are involved in the synthesis of dTMP (2'-deoxythymidine-5'-phosphate) from dUMP (2'-deoxyuridine-5'-phosphate). It helps convert vitamin B12 to one of its coenzyme forms and helps synthesize the DNA required for all rapidly growing cells.
The pathway leading to the formation of tetrahydrofolate (FH4) begins when folate (F) is reduced to dihydrofolate (FH2), which is then reduced to tetrahydrofolate (FH4). Dihydrofolate reductase catalyses both steps.
Methylene tetrahydrofolate (CH2FH4) is formed from tetrahydrofolate by the addition of methylene groups from one of three carbon donors: formaldehyde, serine, or glycine. Methyl tetrahydrofolate (CH3鈥揊H4) can be made from methylene tetrahydrofolate by reduction of the methylene group; formyl tetrahydrofolate (CHO-FH4, folinic acid) results from oxidation of methylene tetrahydrofolate.
In other words:
F 鈫?FH2 鈫?FH4 鈫?CH2=FH4 鈫?1-carbon chemistry
A number of drugs interfere with the biosynthesis of folic acid and tetrahydrofolate. Among them are the dihydrofolate reductase inhibitors (such as trimethoprim and pyrimethamine), the sulfonamides (competitive inhibitors of para-aminobenzoic acid in the reactions of dihydropteroate synthetase), and the anticancer drug methotrexate (inhibits both folate reductase and dihydrofolate reductase).