Microbes in Human Welfare - Online Test
Q1. The chemical substances produced by some microbes and can kill or retard the growth of disease causing microbes are called
Answer : Option A
Explaination / Solution:
Antibiotics, also called antibacterials, are a type of antimicrobial drug used in the treatment and prevention of bacterial infections.They may either kill or inhibit the growth of bacteria.
Q2. Use of biocontrol measures will greatly reduce our dependence on
Answer : Option B
Explaination / Solution:
The use of biocontrol measures will greatly reduce our dependence on toxic chemicals and pesticides. Insects and pests are not killed in this method but kept undercontrol.
Q3. Which of the following is a gram-negative bacterium?
Answer : Option C
Explaination / Solution:
The bacterium that do not retain the Gram stain are called gram negative bacteria.
Escherichia coli ( commonly abbreviated E. coli) is a Gram-negative gammaproteobacterium commonly found in the lower intestine of warm-blooded organisms
Q4. The common nitrogen-fixer in paddy fields is
Answer : Option A
Explaination / Solution:
Nitrogen is obtained by plants either in nitrate or nitrite forms. Some microbes convert atmospheric nitrogen into nitrate and nitrite. The common nitrogen-fixing microbe in paddy field is Azospirillum.
Q5. The most important of the symbiotic nitrogen fixing bacteria which forms nodules on the roots of legume plants is
Answer : Option D
Explaination / Solution:
Rhizobium are bacteria that fix nitrogen after becoming established inside root nodules of legumes. In order to express genes for nitrogen fixation, rhizobia require a plant host; they cannot independently fix nitrogen
Rhizobium bacteria is found in the nodule of leguminous plants root. It increases the fertility of soil.
Q6. The term antibiotic was coined by
Answer : Option A
Explaination / Solution:
The term antibiotic was coined by Selman Abraham Waksman. He developed antibiotic Streptomycin that cure tuberculosis. He got noble prize in medicine in 1952.
Q7. Which of the following organisms not fix atmospheric nitrogen
Answer : Option C
Explaination / Solution:
Spirogyra is a filamentous alga. This alga does not fix atmospheric nitrogen. Anabaena, Nostoc and Oscillatoria can heterocyst that can fix atmospheric nitrogen.
Q8. Cyanobacteria serves as important biofertilizers in the fields of
Answer : Option C
Explaination / Solution:
Rice field contain water all the time. In this water Cyanobacteria grows easily that have ability to fix atmospheric nitrogen into nitrates and nitrites that increase the fertility.
Q9. Fleming, Chain and Florey were awarded the Nobel Prize in 1945 for discovery of
Answer : Option A
Explaination / Solution:
Fleming, Chain and Florey were awarded the Nobel Prize in 1945 for discovery of antibiotics. Antibiotics prevent the growth of bacteria and fungi.
Q10. A nitrogen fixing microbe associated with Azolla in rice fields is
Answer : Option A
Explaination / Solution:
A number of microbes are present in rice field, Azolla and Anabaena are two common bacteria found in rice field that fix the atmospheric nitrogen.
