Question

Read the sources given and answer any four from the questions given below:

An antibiotic is a chemical substance which is produced by certain microbes (bacteria and fungi) and can kill or inhibit the growth of other disease-causing microbes. Most antibiotics treat bacterial infections but some can treat certain parasitic or fungal infections also. The antibiotic penicillin was discovered by Sir Alexander Fleming in 1928. It was extracted from a microscopic fungus Penicillium notatum. Fleming was studying the bacterium, Staphylococcus that causes throat infection in humans. He noticed that one culture of this bacteria was contaminated with a fungus. In that culture, the colonies of Staphylococcus immediately surrounded by the fungus had been destroyed but other colonies further away were normal. Penicillin has been used to treat tonsillitis, throat infections and different types of wound infections. Penicillin prevents the bacteria from synthesising peptidoglycan and blocks cross-linking of cell wall. After penicillin, many antibiotics have been extracted from various bacteria and fungi. One of the most productive sources of antibiotics has been the genus Streptomyces, a bacterium of which there are many species, from which over 500 antibiotics have been derived. Most commonly used antibiotics include streptomycin, tetracycline, erythromycin, etc.

1. The antibiotic penicillin was extracted from the following
   1. bacteria
   2. fungus
   3. cyanobacteria
   4. lichen
2. Staphylococcus causes the following in humans
   1. wound infection
   2. skin infection
   3. throat infection
   4. stomach infection
3. A large number of antibiotics have been derived from
   1. fungus Streptomyces
   2. bacteria Streptomyce
   3. Streptomycin
   4. Staphylococcus
4. An antibiotic is a chemical substance that is produced by certain
   1. bacteria
   2. fungi
   3. both (a) and (b)
   4. protozoans
5. How does antibiotic penicillin help to treat infections?
   1. It inhibits synthesis of bacterial cell wall
   2. It kills the bacteria
   3. It produces bactericidal chemicals
   4. It encircles bacteria and destroys them

Answer 1

1. fungus
2. throat infection
3. bacteria Streptomyce
4. both (a) and (b)
5. It inhibits synthesis of bacterial cell wall