Online Test — Microbes in Human Welfare
15 Questions • 15 min • Chapter MCQ
15:00
Question 1 of 15
Most microbes are:
Always harmful
Harmless or useful
Never useful
Plants
Explanation: Most microbes are harmless or useful to humans.
Question 2 of 15
Curd is made from milk by:
Lactic acid bacteria
Yeast
Viruses
Algae
Explanation: Lactic acid bacteria turn milk into curd.
Question 3 of 15
Bread dough rises because yeast produces:
Oxygen
Carbon dioxide
Nitrogen
Water only
Explanation: Yeast fermentation produces CO₂, which makes dough rise.
Question 4 of 15
Alcohol and beverages are produced by yeast through:
Fermentation
Photosynthesis
Respiration in light
Digestion
Explanation: Yeast ferments sugars to make alcohol.
Question 5 of 15
The first antibiotic, penicillin, was discovered by:
Mendel
Alexander Fleming
Darwin
Watson
Explanation: Fleming discovered penicillin from Penicillium.
Question 6 of 15
Antibiotics are medicines that:
Kill or stop bacteria
Make food rise
Fix nitrogen
Produce biogas
Explanation: Antibiotics kill or stop the growth of bacteria.
Question 7 of 15
In sewage treatment, organic matter is broken down by:
Microbes
Salt
Boiling
Freezing
Explanation: Microbes digest the organic matter in sewage.
Question 8 of 15
The main gas in biogas is:
Oxygen
Methane
Nitrogen
Carbon dioxide
Explanation: Biogas is rich in methane.
Question 9 of 15
Microbes that produce biogas are called:
Methanogens
Carcinogens
Pathogens
Antigens
Explanation: Methanogens produce methane-rich biogas.
Question 10 of 15
Cattle dung is used to start a biogas plant because it contains:
Methanogen microbes
Penicillin
Antibodies
Vitamins only
Explanation: Cattle dung supplies methanogens from the cattle gut.
Question 11 of 15
Living microbes that enrich the soil with nutrients are:
Biofertilisers
Pesticides
Antibiotics
Vaccines
Explanation: Biofertilisers naturally enrich the soil.
Question 12 of 15
Rhizobium enriches soil by:
Fixing nitrogen
Killing insects
Making curd
Producing alcohol
Explanation: Rhizobium fixes atmospheric nitrogen in legume nodules.
Question 13 of 15
A fungus that partners with roots to help absorb phosphorus is:
Mycorrhiza
Yeast
Penicillium
Anabaena
Explanation: Mycorrhiza helps roots absorb phosphorus and water.
Question 14 of 15
Controlling pests using living organisms instead of chemicals is:
Biocontrol
Fermentation
Vaccination
Metastasis
Explanation: Biocontrol uses living organisms to control pests.
Question 15 of 15
Bacillus thuringiensis (Bt) is used to kill:
Certain insect larvae
All plants
Useful bacteria
Humans
Explanation: Bt kills specific insect larvae and is harmless to others.