This set of Class 12 Biology Chapter 10 Multiple Choice Questions & Answers (MCQs) focuses on “Microbes in Industrial Products-2”.
1. Who coined the term antibiotics?
Explanation: The term antibiotics was coined by Waksman in 1942. Clinically, an antibiotic is a substance produced by a microorganism which is in low concentration and inhibits the growth and metabolic activity of pathogenic organisms without harming the host.
2. Who was the first person to discover an antibiotic?
a) Rene Dubois
b) Alexander Fleming
d) Louis Pasteur
Explanation: The first antibiotic is generally associated with the name of Alexander Fleming when he discovered Penicillin from Penicillium notatum in 1928. Penicillium notatum did not allow the growth of Staphylococcus aureus.
3. Broad-spectrum antibiotics can kill only a small number of pathogens.
Explanation: Broad Spectrum antibiotic is an antibiotic which can kill or destroy several pathogens that belong to different groups with different structures and wall composition.
4. Which of the following is not a method by which antibiotic functions?
a) Disruption of wall synthesis
b) Inhibition of 50S ribosome
c) Inhibition of DNA synthesis
d) Permitting the growth of bacteria
Explanation: Antibiotic functions by the disruption of wall synthesis of bacteria, Inhibition of 50 S ribosome function, Inhibition of translation, Inhibition of DNA synthesis, Disruption of plasmalemma repair and synthesis, etc.
5. Which of the following is not the characteristic of a good antibiotic?
a) Harmless to host
b) Ability to destroy the pathogen
c) Ability to destroy all the microflora in the alimentary canal of the host
d) Effective against all strains of pathogens
Explanation: A good antibiotic is harmless to host with no side effects, harmless to normal microflora of the alimentary canal of the host, Ability to destroy all strains of the pathogen and has a quick action.
6. Which of the following may be a reason for the development of resistance to antibiotics?
a) Mutation in the pathogen
b) Very effective antibiotic
c) Very weak pathogen
d) Can never happen
Explanation: Pathogens often develop resistance to existing antibiotics so that newer antibiotics are required to be produced. The resistance is produced due to the development of copious mucilage, Alternation of the cell membrane of bacteria which prevents antibiotic entry and mutation in the pathogen.
7. From which of the following species an antibiotic is generally not obtained?
Explanation: Antibiotics are generally obtained from lichens, fungi, eubacteria and actinomycetes. Over 7000 antibiotics are known. Every year some 300 new antibiotics are discovered using hypersensitive microorganisms.
8. Which of the following is a common antibiotic obtained from lichens?
a) Usnic acid
Explanation: The common antibiotics obtained from lichens is usnic acid from Usnea and Cladonia. Fungi yield several antibiotics like penicillin, polyporin, clavacin, clitocybin, etc.
9. For which of the following purpose, antibiotics are not used?
a) For killing essential bacteria
b) As medicines
c) As preservatives
d) As feed supplements
Explanation: Antibiotics are not used for killing essential bacteria. They are used as medicines, preservatives in perishable food articles and as feed supplements for animals especially poultry birds.
10. Streptomyces is an antibiotic obtained from actinomycetes.
Explanation: Streptomyces is an antibiotic obtained from actinomycetes. Other antibiotic yielding actinomycetes are Streptoverticillium, Micromonospora, Nocardia, Actinoplanes, etc.
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