How has the bacterium Bacillus thuringiensis helped us in controlling caterpillars of insect pests?
Bacillus thuringiensis produces an are endotoxin which, when ingested and released in the gut of the larvae of insect pest disrupts the insect gut lining thereby killing them.
How do mycorrhizal fungi help the plants harbouring them?
The mycorrhizal fungi absorb phosphorus from the soil and transfer them to the host cells. They also impart resistance to host plants against root pathogens. They also show tolerance to salinity and draught as well as increases overall growth and development of plant.
Hence, fungal hyphae help in synthesising organic food and also recieve/get shelter and nourishment from the higher plant.
Why are cyanobacteria considered useful in paddy fields?
Cyanobacteria like Anabaena, Nostoc, Oscillatoria serve as an important biofertiliser in paddy fields as they fix atmospheric nitrogen and add organic matter to the soil and increase its fertility.
How was penicillin discovered?
Penicillin was the first antibiotic to be discovered and it was a chance discovery. Sir, Alexander Fleming observed that in unwashed culture plates of Staphylococcus, a mould Penicillium was growing.
This mould inhibited the growth of Staphylococcus. Later the antibiotic was isolated from this fungus and named penicillin after the mould Penicillium notatum.
Name the scientists who were credited for showing the role of penicillin as an antibiotic?
Penicillin was discovered by Sir Alexander Fleming while, working on Staphylococci bacteria. However, its full potential as an effective antibiotic was established much later by Ernst Chain and Howard Florey.
This antibiotic was extensively used to treat American soldiers wounded in World War II. Fleming, Chain and Florey were awarded the Nobel Prize in 1945, for this discovery.