10

Q1. Methanogens growing anaerobically on cellulosic material produce

• Methane
• Methane and carbon dioxide
• Methane and hydrogen
• Methane, carbon dioxide and hydrogen.

Solution

Certain bacteria grow anaerobically on cellulosic material and produce large amounts of methane along with carbon dioxide and hydrogen. These bacteria are collectively called methanogens. Examples of methanogens are Bacillus, Cellulomonas, Clostridium, Eubacterium and Ruminococcus. They play a very important role in nutrition of cattle by digesting the cellulosic material.

Q2. The major component of biogas is

• Methane
• Oxygen
• Hydrogen
• Nitrogen

Solution

Methane is the major component of biogas, consisting of about 50-68% of the total gas.

Q3. Alexander Fleming is associated with 

• Yeast fermentation
• Ethanol production
• Penicillin
• Anthrax

Solution

Alexander Fleming discovered the antibiotic penicillin and explored its possible therapeutic use.

Q4. An example of endomycorrhiza is

• Nostoc
• Glomus
• Agaricus
• Rhizobium

Solution

Glomus is a genus of arbuscular mycorrhizal (AM) fungi which is used as a biofertiliser. Nostoc is a cyanobacterial biofertliser. Agaricus is a genus of mushrooms. Rhizobium forms an endosymbiotic nitrogen fixing association with roots of legumes and Parasponia.

Q5. Expand LAB.

• Lactic acid biogenesis
• Lactic acid bacteria
• Latent antibiotic bacteria
• Latent antibiotic biogenesis

Solution

LAB stands for lactic acid bacteria, which are used in various fermentation processes.

Q6. The term antibiotic was first used by

• Flemming
• Pasteur
• Waksman
• Lister

Solution

Antibiotics are chemical compounds produced by microorganisms that inhibit or slow down the growth of bacteria. The term antibiotic was first used by Selman Waksman and his collaborators in 1942 in journal articles to describe any substance produced by a microorganism that is antagonistic to the growth of other microorganisms in high dilution.

Q7. Which of the following gases is not produced in a biogas plant?

• Hydrogen
• Methane
• Oxygen
• Sulphur

Solution

The major gas produced in a biogas plant is methane, which accounts for about 50-68% of the total gases produced. The other gases produced include hydrogen, carbon dioxide, nitrogen, oxygen and, in some cases, hydrogen sulphide.

Q8. Which one of the following microbes is used in the commercial production of ethanol?

• Clostridium butyricum
• Streptococcus spp.
• Trichoderma polysporum
• Saccharomyces cerevisiae

Solution

The yeast Saccharomyces cerevisiae is used in the brewing industry for the preparation of alcoholic drinks like ethanol, beer, wine etc. through fermentation. Certain Streptococcus species produce lactic acid. Trichoderma polysporum is being developed as an effective biocontrol agent of several plant pathogens.  Clostridium butyricum is a bacterium used for the production of butyric acid.

Q9. Probiotics are

• Cancer inducing microbes
• New kind of food allergens
• Live microbial food supplement
• Safe antibiotics

Solution

Probiotics are live microorganisms like bacteria and yeast that are similar to microorganisms found naturally in the human body and may be beneficial to human health. They influence the intestinal microflora and bring about alterations in food quality.

Q10. Which cheese is characterised by large holes?

• Cottage cheese
• Goat cheese
• Swiss cheese
• Roquefort cheese

Solution

Swiss cheese is known for its characteristic flavour and large holes. These holes are formed due to the production of a large amount of CO_2­ during the fermentation process.

Q11. The aquatic fern which is an excellent example of a biofertiliser is

• Azolla
• Pteridium
• Salvinia
• Marsilea

Solution

Leaves of Azolla carry colonies of Anabaena, which help fix nitrogen and make it available to plants. Hence, Azolla is used as a biofertiliser to supply nitrogen to plants.

Q12. Maximum number of antibiotics are got from any group except for

• Actinomycetes
• Fungi
• Eubacteria
• Viruses

Solution

All antibiotics are obtained from microorganisms. Majority of the antibiotics are produced mainly from three groups of microorganisms - Eubacteriales (true bacteria), Actinomycetales (ramified bacteria) and fungi. Viruses do not produce any kind of antibiotic.

Q13. The residue left after methane production from cattle dung is

• Burnt
• Buried in landfills
• Used as manure
• Used in civil construction

Solution

The residue left after methane production from cattle dung includes microbial solids in the form of sludge, fibre and wastewater. This residue is a potentially valuable fertilizer or compost.

Q14. Identify the fungus with medicinal importance.

• Penicillium
• Cercospora
• Agaricus
• Saccharomyces

Solution

The antibiotic penicillin is obtained from the fungus Penicillium notatum. It inhibits cell wall synthesis. Cercospora are parasitic fungi and infect a broad range of herbaceous plants. Agaricus is a genus of mushrooms that contains both edible and poisonous species. Saccharomyces is a genus of fungi involved in commercial alcohol and bread production.

Q15. Which one of the following is not used in organic farming?

• Snail
• Glomus
• Earthworm
• Oscillatoria

Solution

Organic farming refers to the use of biofertilisers or the organisms that enrich the nutrient quality of the soil. Glomus is a genus of arbuscular mycorrhizal (AM) fungi which is used as a biofertiliser. Earthworms are employed to obtain an eco-friendly compost called vermicompost. Cyanobacteria like Oscillatoria are used to inoculate rice fields to obtain higher yields. Use of snails in organic farming has not been reported still.

Q16. Rotenone is a

• Bioherbicide
• Commonly used biofertilizer
• Bioinsecticide
• Juvenile hormone

Solution

Rotenone is an odourless and colourless ketonic chemical compound. It occurs naturally in the seeds and stems of several plants such as the jicama vine plant and the roots of several members of family Fabaceae. Rotenone is used as a pesticide, insecticide and a non-selective piscicide (fish killer).

Q17. Bacillus thuringiensis (Bt) strains have been used for designing novel

• Bio-fertilisers
• Bio-metallurgical techniques
• Bio-mineralisation processes
• Bio-insecticidal plants

Solution

The bacterium Bacillus thuringiensis (Bt) strains contains genes for insecticidal crystal proteins. These have been isolated from the bacteria and incorporated into the genetic material of various crop plants through recombinant DNA technology. Bt-cotton is one such example of bio-insecticidal plant.

Q18. Heterocysts that take part in nitrogen fixation occur in

• Nostoc
• Polysiphonia
• Fucus
• Ulothrix

Solution

Heterocysts are specialized nitrogen-fixing cells found in some filamentous cyanobacteria such as Nostoc. They fix atmospheric nitrogen into using the enzyme nitrogenase in order to provide the filamental cells with nitrogen for biosynthesis.

Q19. Which of the following is a product of yeast fermentation?

• Caproic acid
• Lactic acid
• n-Propanol
• All of the above

Solution

Some of the products obtained from yeast fermentation are ethanol, caproic acid, lactic acid, n-propanol, glycerol, butanol and acetaldehyde.

Q20. VAM contains

• Symbiotic bacteria
• Saprophytic bacteria
• Symbiotic fungi
• Saprophytic fungi

Solution

Vesicular Arbuscular Mycorrhiza (VAM) is an important mycorrhizal association. In this association, the fungal mycelium forms some special kinds of organs called vesicles and arbuscules within the root cortical cells. The vesicles and arbuscules serve as the food storage organs of the fungus.

Q21. Rennin used in the cheese industry is

• Antibiotic
• Alkaloid
• Enzyme
• Inhibitor

Solution

Rennet is extracted from the calf stomach. It contains the enzyme rennin. Rennin helps in coagulation of milk causing it to separate into curd and whey.

Q22. Which bacterium is used in the production of Swiss cheese?

• Streptococcus faecalis
• Pedicoccus cerevisiae
• Propionibacterium sharmanii
• Penicillium roqueforti

Solution

Propionibacterium sharmanii is used in the production of Swiss cheese. The bacterium gives the cheese its characteristic flavour and is responsible for the large holes in the cheese body. 

Q23. Lactic acid is formed by the process of

• Fermentation
• Glycolysis
• HMP Pathway
• None of these

Solution

The lactose sugar of milk is converted into lactic acid through fermentation by lactic acid bacteria such as Lactobacillus. Apart from the conversion of milk into lactic acid, the LAB also improve its nutritional quality by enhancing vitamin B₁₂ content.

Q24. The bacterium responsible for curd formation is

• Streptococcus thermophilus
• Saccharomyces cerevisiae
• Leuconostoc mesenteroides
• Pedicoccus cerevisiae

Solution

The two most commonly used bacteria which help convert milk to curd are Lactobacillus bulgaricus and Streptococcus thermophilus.

Q25. Which of the following is a non-symbiotic biofertiliser?

• Vesicular arbuscular mycorrhizae
• Azotobacter
• Anabaena
• Rhizobium

Solution

Azotobacter is a free-living, non-symbiotic nitrogen-fixing bacterium found in the soil. It fixes atmospheric nitrogen and makes it available to plants.

Q26. Toddy is prepared by the fermentation of

• Latex of toddy palm
• Coconut water
• Dried fish
• Both latex of toddy palm and coconut water

Solution

Toddy is prepared by the fermentation of the latex of toddy palm and coconut water.

Q27. A sewage treatment process in which a part of the decomposer bacteria present in the wastes are recycled into the starting of the process is called

• Cyclic treatment
• Activated sludge treatment
• Primary treatment
• Tertiary treatment

Solution

Activated sludge refers to a mass of microorganisms cultivated in the sewage treatment process to break down organic matter into carbon dioxide, water and other inorganic compounds. The activated sludge treatment process has three basic components- a reactor in which the microorganisms are kept in suspension, aerated and in contact with the waste they are treating, liquid-solid separation and a sludge recycling system for returning activated sludge back to the beginning of the process.

Q28. Which of the following is not degraded during anaerobic digestion of organic waste?

• Cellulose
• Hemicellulose
• Lipid
• Lignin

Solution

Lignin is a complex plant polymeric molecule which remains undigested by anaerobic bacteria during the decomposition of organic waste.

Q29. A good example of organic fertilizer which improves phosphorus uptake is

• Streptomyces
• Saccharomyces
• Azospirillum
• None of these

Solution

Microphos biofertlisers include microorganisms such as Azospirillum, Pseudomonas and Bacillus, which solubilise bound phosphate of rocks and soil to increase the availability of soluble phosphate to the plants. The phosphate dissolving bacteria reduce the pH of the substrate by secretion of a number of organic acids. This causes release of soluble inorganic phosphate into the soil through decomposition of phosphate-rich organic compounds.

Q30. Rotenone is a

• Insect hormone
• Bioherbicide
• Natural herbicide
• Natural insecticide