What is a broad spectrum antibiotic? Name one such antibiotic.
A broad spectrum antibiotic is one which can inhibit the growth of both Gram positive and Gram negative bacteria
e.g.,Tetracyclines, phenicols, fluoroquinolones, third-generation and fourth-generation antibiotivcs is cephalosporins.
What are viruses parasitising bacteria called? Draw a well labelled diagram of the same.
Viruses parasitising bacteria are called bacteriophages. These viruses do not actually eat bacteria. They infect and replicate within the bacteria.
Which bacterium has been used as a clot buster? What is its mode of action?
The bacterium Streptococcus that produces streptokinase is used as a 'clot buster'.
This enzyme has a fibrinolytic action that breaks down the clots formed in the blood vessels of patients who have undergone myocardial infarction. This prevents heart attack in these patients that can otherwise occur because of occlusion by the clots.
What are biofertilisers? Give two examples.
Biofertilisers are organisms that enrich the nutrient quality of the soil. The main source of biofertilizers are bacteria, fungi and cyanobacteria.
e.g.,
(i) Azospirillum, Rhizobium and Azotobacter can fix atmospheric nitrogen in the soil.
(ii) Blue-green algae like Anabaena, Nostoc, Occilatoria add organic matter to the soil and responsible for increase its fertility.
Why is aerobic degradation more important than anaerobic degradation for the treatment of large volumes of wastewaters rich in organic matter. Discuss.
Aerobic degradation is more important as naturally occurring aerobic and facultative microbes (bacteria, fungi, Protozoa and others) in the waste water can rapidly oxidise soluble organic and nitrogenous compounds.
Mechanical addition of oxygen makes the process faster and most of the pathogenic content of the effluent is removed.