The fungus from which the antibiotic penicillin was originally extracted is: MCQ with Answer and Explanation

Explanation:
Typhoid fever is a bacterial disease caused by Salmonella enterica serotype Typhi. Ringworm is a superficial fungal infection caused by dermatophytes like Microsporum and Trichophyton. Malaria is not caused by a virus; it is caused by a protozoan parasite of the genus Plasmodium. Therefore, statements 1 and 3 are correct, while 2 is false.

Explanation:
Folic acid (vitamin B₉) is reduced to tetrahydrofolate (THF), which carries one-carbon groups in amino acid and nucleotide metabolism. Biotin is for carboxylation, riboflavin for redox, thiamine for decarboxylation.

Explanation:
Down syndrome, the most common chromosomal aneuploidy, is caused by an extra copy of chromosome 21 (trisomy 21), usually from nondisjunction during meiosis. It is characterized by intellectual disability, distinct facial features, and increased risk of certain medical conditions. Monosomy X is Turner syndrome.