The correct option is (a).
Explanation
Antibiotics are chemical substances, produced by certain microbes, which function to kill or retard the growth of other disease-causing microbes (pathogens). They are a cornerstone of modern medicine in treating bacterial infections.
Statement-wise Analysis:
- Statement 1 is Correct: Antibiotics are indeed medicines produced from microorganisms (such as bacteria and fungi) that are used to kill or stop the growth of disease-causing microbes. The term "antibiotic" translates to "against life" (in the context of disease-causing organisms).
- Statement 2 is Incorrect: While Penicillin was the first antibiotic to be discovered, it was obtained from a mould (fungus) known as Penicillium notatum, not from a bacterial culture of E. coli. This discovery was made by Alexander Fleming.
- Statement 3 is Incorrect: Antibiotics are effective only against bacterial infections. They target specific mechanisms in bacteria, such as cell wall synthesis. Viruses do not possess these mechanisms and live inside host cells; therefore, antibiotics are ineffective against viral diseases like the common cold and flu.
Key Takeaway:
Antibiotics are antimicrobial drugs derived from microbes (mainly fungi and bacteria) that target bacterial infections; they are ineffective against viral infections, and Penicillin (the first antibiotic) was derived from a fungus.