Test: Biology in Human Welfare (January 24) - NEET MCQ

Microbes such as Lactobacillus and others commonly called lactic acid bacteria (LAB) grow in milk and convert it into curd.

Hence, the correct option is C.
NCERT Reference: Topic- " MICROBES IN HOUSEHOLD PRODUCTS” of chapter "Microbes in Human Welfare" of NCERT 

Saccharomyces is a yeast that is used to ferment sugar to produce ethanol in absence of oxygen or by anaerobic respiration.

Hence, the correct option is B.
NCERT Reference: Topic Fermented Beverages” of chapter "Microbes in Human Welfare" of NCERT.  

Bio-fertilizer enriches the nutrient in the soil. The main sources of bio-fertilizers are bacteria, fungi and cyanobacteria.

Hence, the correct option is D.
NCERT Reference: Topic- MICROBES AS BIOFERTILISERS” of chapter "Microbes in Human Welfare" of NCERT.  

• The puffed-up appearance of dough is due to the production of CO₂ gas.
• Baking soda (sodium hydrogen carbonate) on heating releases carbon dioxide gas along with sodium carbonate.

Hence, the correct option is B.
NCERT Reference: Topic- MICROBES IN HOUSEHOLD PRODUCTS of chapter "Microbes in Human Welfare" of NCERT.  

Secondary treatment of sewage is also called biological treatment because in this treatment aeration of sewage water is done that increases the microbes that decompose the organic materials in sewage water.

Hence, the correct option is A.
NCERT Reference: Topic- MICROBES IN SEWAGE TREATMENT” of chapter "Microbes in Human Welfare" of NCERT.  

• Spirogyra is a filamentous alga. This alga does not fix atmospheric nitrogen.
• Anabaena, Nostoc and Oscillatoria can fix atmospheric nitrogen.

Hence, the correct option is B.
NCERT Reference:  Topic: MICROBES AS BIOFERTILIZERS” of chapter "Microbes in Human Welfare" of NCERT. 

• Yeast is used in the production of alcohol, wine-making and in baking bread.
• Saccharomyces cerevisiae is known as baker's yeast and Saccharomyces ellipsoidens is called wine yeast. 

Hence, the correct  option is D.
NCERT Reference: Topic- Fermented Beverages” of chapter "Microbes in Human Welfare" of NCERT.  

• The biogas-producing bacteria are collectively known as methanogens and one such common bacterium is Methanobacterium.
• These bacteria are commonly found in the anaerobic sludge during sewage treatment and also in the rumen of cattle.

Hence, the correct option is D.

NCERT Reference: Topic- MICROBES IN PRODUCTION OF BIOGAS” of chapter "Microbes in Human Welfare" of NCERT.  

• The type of gas produced depends upon the microbes and the organic substrates they utilise.
• Example: In the fermentation of dough, cheese making and production of beverages, the main gas produced is CO₂.

Hence, the correct option is C.
NCERT Reference: Topic- MICROBES IN PRODUCTION OF BIOGAS” of chapter "Microbes in Human Welfare" of NCERT.  

• The first organic acid produced by microbial fermentation was lactic acid.
• Lactic acid is produced by the anaerobic respiration of glucose.

Hence, the correct option is C.
NCERT Reference: Topic- Chemicals, Enzymes and other Bioactive Molecules” of chapter "Microbes in Human Welfare" of NCERT.  

• Atmospheric nitrogen is not available to plants. There are certain nitrogen-fixing bacteria that convert atmospheric nitrogen into ammonium compounds and make them available to the plants.
  Examples: Azotobacter, Frankia, Rhizobium, Azospirillum.
• Out of these, Azospirillum is widely used as a nitrogen fixer organism in paddy fields. It is used as a biofertilizer in rice fields. It promotes plant growth.

Hence, the correct option is D.
NCERT Reference: Topic- MICROBES AS BIOFERTILIZERS” of chapter "Microbes in Human Welfare" of NCERT.  

• Rhizobium is a nitrogen-fixing bacteria found in the nodule of a leguminous plant's root.
• These bacteria fix atmospheric nitrogen into organic forms, which is used by the plant as nutrient.
• It increases the fertility of the soil.

Hence, the correct option is D.
NCERT Reference: Topic: MICROBES AS BIOFERTILIZERS” of chapter "Microbes in Human Welfare" of NCERT.  

• Baculoviruses are pathogens that attack insects and other arthropods.
• The majority of baculoviruses used as biological control agents fall under the genus Nucleopolyhedrovirus.

Hence, the correct option is C.
NCERT Reference: Topic- MICROBES AS BIOCONTROL AGENTS” of chapter "Microbes in Human Welfare" of NCERT.  

Both the assertion and reason are correct, but the reason is not an explanation of the assertion.

Assertion: Biofertilizers are organisms that enrich the nutrient quality of the soil.
Explanation: Biofertilizers are living microorganisms that, when applied to seeds, plant surfaces, or soil, colonize the rhizosphere or the interior of the plant and promote growth by increasing the supply or availability of primary nutrients to the host plant. They are a natural and environmentally friendly way to provide essential nutrients to plants, which in turn boosts soil fertility and productivity.

Reason: Organic farming is the farming technique in which no chemical is used as fertilizers or insecticides.
Explanation: Organic farming is an agricultural system that seeks to provide the consumer with fresh, tasty, and authentic food while respecting natural life-cycle systems. It involves the use of natural fertilizers, such as compost, manure, and green manure, instead of synthetic fertilizers. It also relies on natural pest control methods, such as biological control, crop rotation, and the use of resistant plant varieties, instead of chemical pesticides.

While both the assertion and reason are correct statements, the reason does not directly explain the assertion. The assertion is about the role of biofertilizers in enriching soil nutrients, while the reason is about the principles of organic farming, which is a broader concept that encompasses not only the use of biofertilizers but also other natural and sustainable practices.

• Microbes are not used in the production of antiviral drugs and the production of inorganic fertilizers.
• Although, microbes are used in converting milk into curd, antibiotic production, sewage treatment, bread and cheese industry etc.

Hence, the correct option is C.
NCERT Reference: Topic- MICROBES IN SEWAGE TREATMENT” and  MICROBES IN INDUSTRIAL PRODUCTS” of chapter "Microbes in Human Welfare" of NCERT.