Maharashtra Board Class 12 Biology Chapter 11 Enhancement of Food Production Solutions

Class 12 Biology Chapter 11 Exercise Solutions Maharashtra Board

1. Multiple Choice Questions

Question 1.Antibiotic Chloromycetin is obtained from ..............
(a) Streptomyces erythreus
(b) Penicillium chrysogenum
(c) Streptomyces venezuelae
(d) Streptomyces griseus
Answer: (c) Streptomyces venezuelae
In simple words: Chloromycetin is an antibiotic made by a specific type of soil bacteria called Streptomyces venezuelae.

🎯 Exam Tip: Remember the specific microbial sources for common antibiotics as they are frequently asked in MCQs.

Question 2.Removal of large pieces of floating debris, oily substances, etc. during sewage treatment is called ................
(a) primary treatment
(b) secondary treatment
(c) final treatment
(d) amplification
Answer: (a) primary treatment
In simple words: Primary treatment in sewage processing involves physically removing large floating and settled solids from the wastewater.

🎯 Exam Tip: Differentiate clearly between primary, secondary, and tertiary sewage treatments, focusing on the main processes involved in each stage.

Question 3.Which one of the following is free living bacterial biofertilizer?
(a) Azotobacter
(b) Rhizobium
(c) Nostoc
(d) Bacillus thuringiensis
Answer: (a) Azotobacter
In simple words: Azotobacter is a bacterium that lives freely in the soil and helps plants by fixing atmospheric nitrogen, acting as a natural fertilizer.

🎯 Exam Tip: Know the difference between free-living and symbiotic biofertilizers and their respective examples.

Question 4.Most commonly used substrate for industrial production of beer is ................
(a) barley
(b) wheat
(c) corn
(d) sugar cane molasses
Answer: (a) barley
In simple words: Barley grains are the primary ingredient used in the industrial process to ferment and produce beer due to their high starch content.

🎯 Exam Tip: Be aware of the raw materials and microorganisms used in various industrial microbial processes like brewing and ethanol production.

Question 5.Ethanol is commercially produced through a particular species of ................
(a) Aspergillus
(b) Saccharomyces
(c) Clostridium
(d) Trichoderma
Answer: (b) Saccharomyces
In simple words: The yeast Saccharomyces cerevisiae, commonly known as brewer's yeast, is widely used to ferment sugars into ethanol for commercial purposes.

🎯 Exam Tip: Connect specific microbes to their industrial products, especially for fermentation processes.

Question 6.One of the free-living anaerobic nitrogen- fixers is ................
(a) Azotobacter
(b) Beijerinckia
(c) Rhodospirillum
(d) Rhizobium
Answer: (c) Rhodospirillum
In simple words: Rhodospirillum is a type of bacterium that can fix atmospheric nitrogen while living freely in oxygen-free environments.

🎯 Exam Tip: Pay attention to the conditions (aerobic/anaerobic) and lifestyle (free-living/symbiotic) when studying nitrogen-fixing microorganisms.

Question 7.Microorganisms also help in production of food like ................
(a) bread
(b) alcoholic beverages
(c) vegetables
(d) pulses
Answer: (a) bread
In simple words: Microorganisms, especially yeast, are crucial in baking bread, causing the dough to rise through fermentation.

🎯 Exam Tip: List several food products where microbial fermentation plays a vital role.

Question 8.MOET technique is used for ................
(a) production of hybrids
(b) inbreeding
(c) outbreeding
(d) outcrossing
Answer: (a) production of hybrids
In simple words: MOET (Multiple Ovulation Embryo Transfer) is a breeding technique used in animals to produce many offspring from a superior female, often resulting in hybrids.

🎯 Exam Tip: Understand the purpose and basic mechanism of advanced animal breeding techniques like MOET.

Question 9.Mule is the outcome of ................
(a) inbreeding
(b) artificial insemination
(c) interspecific hybridization
(d) outbreeding
Answer: (c) interspecific hybridization
In simple words: A mule is a hybrid animal resulting from the cross-breeding of two different species: a female horse and a male donkey.

🎯 Exam Tip: Remember examples of interspecific hybridization and its significance in animal breeding.

2. Very Short Answer Questions

Question 1.What makes idlis puffy?
Answer: During preparation of idlis, rice and black gram flour is fermented by air borne Leuconostoc and Streptococcus bacteria. CO2 produced during fermentation makes them puffy.
In simple words: Idlis become puffy because bacteria like Leuconostoc and Streptococcus ferment the batter, releasing carbon dioxide gas which creates air pockets.

🎯 Exam Tip: Focus on the specific microorganisms and the gas produced during fermentation that causes puffiness in fermented foods.

Question 2.Bacterial biofertilizers.
Answer: Rhizobium, Frankia, Pseudomonas striata, Bacillus polymyxa, Agrobacterium, Microccocus, Azotobacter, Costridium, Beijerinkia, Klebsiella.
In simple words: Bacterial biofertilizers are beneficial bacteria that enhance soil fertility by providing nutrients to plants, such as through nitrogen fixation.

🎯 Exam Tip: Be able to list at least 4-5 common bacterial biofertilizers.

Question 3.What is the microbial source of vitamin B12?
Answer: The microbial source of vitamin B12 is Pseudomonas denitrificans.
In simple words: Vitamin B12 is primarily produced by specific bacteria, one key example being Pseudomonas denitrificans.

🎯 Exam Tip: Associate important vitamins with their microbial production sources, especially for industrial applications.

Question 4.What is the microbial source of enzyme invertase?
Answer: The microbial source of enzyme invertase is Saccharomyces cerevisiae.
In simple words: The enzyme invertase, which breaks down sucrose, is obtained from yeast, specifically Saccharomyces cerevisiae.

🎯 Exam Tip: Learn the microbial sources of common industrial enzymes.

Question 5.Milk starts to coagulate when Lactic Acid Bacteria (LAB) are added to warm milk as a starter. Mention any two other benefits of LAB.
Answer: Lactic Acid Bacteria (LAB) check the growth of disease causing microbes and produce vitamin B.
In simple words: Besides coagulating milk, Lactic Acid Bacteria also help prevent the growth of harmful bacteria and produce essential B vitamins.

🎯 Exam Tip: List multiple benefits of beneficial microbes, not just their primary function.

Question 6.Name the enzyme produced by Streptococcus bacterium. Explain its importance in medical sciences.
Answer: The enzyme produced by Streptococcus spp. is streptokinase. It is used as a 'clot buster' for clearing blood clots in the blood vessels in heart patients.
In simple words: Streptococcus bacteria produce streptokinase, an enzyme vital in medicine for dissolving blood clots in patients suffering from heart conditions.

🎯 Exam Tip: Understand the medical applications of microbially-derived enzymes, especially "clot busters."

Question 7.What is breed?
Answer: Breed is a group of animals related by descent and similar in most characters like general appearance, features, size, configuration, etc.
In simple words: A breed is a distinct group of animals that share common ancestors and have similar physical traits and characteristics.

🎯 Exam Tip: Define key terms in animal husbandry accurately.

Question 8.Estuary
Answer: Estuary is a place where river meets the sea.
In simple words: An estuary is a coastal body of water where freshwater from rivers mixes with saltwater from the ocean.

🎯 Exam Tip: Understand basic ecological terms related to aquatic environments.

Question 9.What is shellac?
Answer: Shellac is the pure form of lac obtained by washing and filtering.
In simple words: Shellac is a natural resin that is purified from lac, a substance secreted by female lac insects.

🎯 Exam Tip: Define terms related to commercially important biological products.

3. Short Answer Questions

Question 1.Many microbes are used at home during preparation of food items. Comment on such useful ones with examples.
Answer:
1. Many food preparations made at home involves the use of microorganisms.
2. The microbes Lactobacilli are used in the preparation of dhokla from gram flour and buttermilk by the process of fermentation.
3. Dosa and idlis are prepared by using batter of rice and black gram which is fermented by air borne Leuconostoc and Streptococcus bacteria.
4. Large, fleshy fruiting bodies of some mushrooms and truffles are directly used as food. It is sugar free, fat free food rich in proteins, vitamins, minerals and amino acids. It is food with low calories.
5. Curd is prepared by inoculating milk with Lactobacillus acidophilus. Lactic acid produced during fermentation causes coagulation and partial digestion of milk protein casein and milk turns into curd.
6. Buttermilk is the acidulated liquid left after churning of butter from curd, is called buttermilk.
In simple words: Microbes like Lactobacilli and yeasts are essential in home cooking, fermenting foods such as dhokla, idli, curd, and mushrooms, adding flavor, texture, and nutritional value.

🎯 Exam Tip: Provide diverse examples of microbial use in home food preparation, linking specific microbes to products.

Question 2.What is biogas? Write in brief about the production process.
Answer: Biogas is a mixture of methane CH4 (50-60%), CO2 (30-40%), H2S (0-3%) and other gases (CO, N2, H2) in traces.
Biogas production process:
a. A typical biogas plant consists of digester (made up of concrete bricks and cement or steel and is partly buried in the soil) and gas holder (a cylindrical gas tank to collect gases).
b. Raw materials like cow dung is mixed with water in equal proportion to make slurry which is fed into the digester' through a side opening (charge pit).
Anaerobic digestion involves following processes:
i. Hydrolysis or solubilization:
Anaerobic hydrolyzing bacteria like Clostridium and Pseudomonas hydrolyse carbohydrates into simple sugars, proteins into amino acids and lipids into fatty acids.
ii. Acidogenesis:
Facultative and obligate anaerobic, acidogenic bacteria convert simple organic substances into acids like formic acid, acetic acid, H2 and CO2
iii. Methanogenesis:
Anaerobic methanogenic bacteria like Methanobacterium, Methanococcus convert acetate, H2 and CO2 into Methane, CO2 and H2O and other products.
\( 12 \text{ mol CH}_3\text{COOH} \)
\( \implies 12\text{CH}_4 + 12\text{CO}_2 \)
\( 4\text{mol H.COOH} \)
\( \implies \text{CH}_4 + 3\text{CO}_2 + 2\text{H}_2\text{O} \)
\( \text{CO}_2 + 4\text{H}_2 \)
\( \implies \text{CH}_4 + 2\text{H}_2\text{O} \)
In simple words: Biogas is a combustible gas mixture, primarily methane, produced when organic waste is broken down by microorganisms in an oxygen-free environment, generating a renewable energy source.

🎯 Exam Tip: Clearly explain the composition of biogas and the three main anaerobic digestion stages: hydrolysis, acidogenesis, and methanogenesis.

Question 3.Biocontrol agents.
Answer:
(1) Biocontrol agents are the organisms like (bacteria, fungi, viruses and protozoans) act which are employed for controlling pathogens, pests and weeds.
(2) They cause the disease to the pest or compete or kill them.
(3) The use of biocontrol measures greatly reduces use of toxic chemicals and pesticides that are harmful to human beings and also pollute our environment.
(4) Biocontrol agents and their hosts.
• Bacteria (Bacillus thuringiensis, B. papilliae and B. lentimorbus Hosts - Caterpillars, cabbage worms, adult beetles
• Fungi (Beauveria bassiana, Entomophothora, pallidaroseum, Zoophthora radicans) Host - Aphid crocci, A. unguicilata, mealy bugs, mites, white flies, etc.
• Protozoans (Nosema locustae) Host: Grasshoppers, caterpillars, crickets
• Viruses (Nucleopolyhedro virus-NPV, Granulovirus-GV) Host - Caterpillars, Gypsy moth, ants and beetles.
(5) Some examples:
• Bacillus thuringiensis (Bt) is a microbiai pesticide used to get rid of butterfly, caterpillars.
• Trichoderma fungus is an effective biocontrol agent against soil borne fungal plant pathogens which infect roots and rhizomes.
• Phytophthora palmiuora is a mycoherbicide that controls milk weed in orchards.
• Pseudomonas spp. is a bacterial herbicide that attacks several weeds.
• Tyrea moth controls the weed Senecio jacobeac.
In simple words: Biocontrol agents are living organisms like bacteria, fungi, or viruses used to naturally control pests, pathogens, and weeds, reducing the need for harmful chemical pesticides.

🎯 Exam Tip: Emphasize the environmental benefits of biocontrol agents and be able to provide examples for each type (bacteria, fungi, protozoans, viruses).

Question 4.Name any two enzymes and antibiotics with their microbial source.
Answer:
1. Microbial source of Chloromycetin. - Streptomyces venezuelae
2. Microbial source of Erythromycin. - Streptomyces erythreus
3. Microbial source of Penicillin. - Penicillium chrysogenum
4. Microbial source of Streptomycin. - Streptomyces griseus
5. Microbial source of Griseofulvin. - Penicillium griseojulvum
6. Microbial source of Bacitracin. - Bacillus licheniformis
7. Microbial source of Oxytetracyclin / Terramycin. - Streptomyces aurifaciens
8. The enzyme produced by Streptococcus bacterium. - Streptokinase
9. Microbial source of Invertase. - Saccharomyces cerevisiae
10. Microbial source of Pectinase. - Sclerotinia libertine, Aspergillus niger
11. Microbial source of Lipase. - Candida lipolytica
12. Microbial source of Cellulase. - Trichoderma konigii
In simple words: Many enzymes and antibiotics, such as streptokinase from Streptococcus (an enzyme) and Chloromycetin from Streptomyces (an antibiotic), are derived from specific microorganisms.

🎯 Exam Tip: Memorize a diverse set of microbial enzymes and antibiotics along with their producing organisms for a comprehensive answer.

Question 5.Write the principles of farm management.
Answer: The principles of farm management are as follows:
1. Selection of high-yielding breeds.
2. Understanding the feed requirements of farm animals.
3. Supply of adequate nutritional sources for the animals.
4. Maintaining the cleanliness of environment.
5. Maintenance of health with the help of veterinary supervision.
6. Undertaking vaccination programmes.
7. Development of high-yielding cross-bred varieties.
8. Making various products and their preservation.
9. Distribution and marketing of the farm produce.
In simple words: Effective farm management includes selecting superior breeds, providing adequate nutrition, maintaining hygiene, controlling diseases, developing cross-bred varieties, and efficient marketing of farm produce.

🎯 Exam Tip: Structure your answer by covering various aspects of animal and environmental care in farm management.

Question 6.Give the economic importance of fisheries.
Answer: Economic importance of fisheries is as follows:
1. Fish is a nutritious food and thus is a source of many vitamins, minerals anc nutrients.
2. Commercial products such as fish oil, fish meal and fertilizers, fish guano, fish glue, isinglass are prepared from fish.
3. These by-products are used in paints, soaps, oils and medicines.
4. Some organisms like prawns and lobsters have high export value and market price.
5. Fish farming and other fishery trades provide job opportunity and self-employment
6. Productivity and national economy is improved through fishery practices.
In simple words: Fisheries provide nutritious food, valuable commercial by-products, create employment opportunities, and significantly contribute to national economies.

🎯 Exam Tip: List diverse economic contributions of fisheries, including food, industrial products, job creation, and export value.

Question 7.Enlist the species of honey bee mentioning their specific uses.
Answer:
(1) The four species of honey bees commonly found in India - Apis dorsata (rock bee, or wild bee), Apis jlorea (little bee), Apis mellifera (European bee) and Apis indica (Indian bee).
(2) Uses:
• Rock bee - They produce 36 kg of honey per comb per year. They produce bee wax.
• Little bee - They produce half kg of honey per hive per year.
• European bee - The average production per colony per year is 25 to 40 kg.
• Indian bee - The average production per colony per year is 6 to 8 kg.
In simple words: Key honey bee species in India include Apis dorsata, Apis florea, Apis mellifera, and Apis indica, each varying in honey and beeswax production capacity.

🎯 Exam Tip: Name the major honey bee species and state their distinguishing characteristics or production yields.

Question 8.What are A, B, C, D in the table given below.

🎯 Exam Tip: Be prepared to complete tables that link microbes to their scientific names, types, and the commercial products they yield.

4. Long Answer Questions

Question 1.Explain the process of sewage water treatment before it can be discharged into natural bodies. Why is this treatment essential?
Answer: Sewage treatment includes following steps:
(1) Preliminary Treatment:
• Screening: The larger suspended or floating objects are filtered and removed in screening chambers by passing the sewage through screens or net in the chambers.
• Grit Chamber : Filtered sewage is passed into series of grit chambers which contain large stones (pebbles) and brick-ballast. Coarse particles which settle down by gravity are removed.
(2) Primary treatment (physical treatment):
• The sewage water is pumped into the primary sedimentation tank where 50-70% of the suspended solid or organic matter get sedimented and about 30-40% (in number) of coliform organisms are removed.
• The organic matter which is settled down is called primary sludge.
• Primary sludge is removed by mechanically operated devices.
• Dissolved organic matter and micro-organisms in the supernatant (effluent) are then removed by the secondary treatment.
(3) Secondary treatment (biological treatment):
• The primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it.
• The mesh like masses of aerobic bacteria, slime and fungal hyphae, known as floes are formed.
• Aerobic microbes consume most of the organic matter and this reduces BOD (Biochemical Oxygen Demand) of the effluent.
(4) Tertiary treatment:
• Once the BOD is sufficiently reduced, waste water is passed into a settling tank where the floes are allowed to sediment.
• The sediment is called activated sludge.
• Small part of activated sludge is transferred to aeration tank and the major part is pumped in to large anaerobic sludge digesters.
• In these tanks, anaerobic bacteria grow and digest the bacteria and fungi in the sludge and gases like methane, hydrogen sulphide, CO2, etc. are released.
• Effluents from these digesters are released in natural water bodies like rivers and streams after chlorination which kills pathogenic bacteria.
• Digested sludge is then disposed.
In simple words: Sewage treatment cleans wastewater through preliminary (physical removal), primary (sedimentation), secondary (biological breakdown), and tertiary (final purification) stages before safe discharge, preventing environmental pollution and health risks.

🎯 Exam Tip: Describe each stage of sewage treatment with specific processes and their outcomes, emphasizing the removal of pollutants and the role of microorganisms.

Question 2.Lac culture.
Answer:
1. Lac is a pink coloured resin secreted by dermal glands of female lac insect (Trachardia lacca) that hardens on coming in contact with air forming lac.
2. Lac is a complex substance having resin, sugar, water, minerals and alkaline substances.
3. Lac insect is colonial in habit and it feeds on succulent twigs like ber, peepal, palas, kusum, babool,
4. These plants are artificially inoculated in order to get better and regular supply of good quality and quantity of lac.
5. Natural lac is always contaminated and pure form of lac obtained by washing and filtering is called as shellac.
6. Lac is used to make bangles, toys, woodwork, inks, mirrors, etc.
7. India's share is 85% of total lac produced in the world.
In simple words: Lac culture involves rearing lac insects (Trachardia lacca) on host plants to harvest lac, a valuable resin used in various industries like bangles, inks, and toys, with India being a major producer.

🎯 Exam Tip: Explain the origin and composition of lac, the process of its cultivation, and its diverse industrial applications.

Question 3.Describe various methods of fish preservation.
Answer:
1. Fish is a highly perishable commodity.
2. After catching the fish it immediately starts spoilage process.
3. In order to prevent this process, the fish preservation is done.
The different methods of fish preservation are as follows:
1. Chilling : This involves covering the fish with layers of ice. Ice is effective for short term preservation. It inhibits the activity of autolytic enzymes.
2. Freezing : It is a long duration preservation method. Fish are freezed at 0°C to -20°C. This also inhibit autolytic enzyme activities and slows down bacterial growth.
3. Freeze drying: The deep frozen -fish at -20°C are dried by direct sublimation of ice to water vapour with any melting into liquid water. This is achieved by exposing the frozen fish to 140°C in a vacuum chamber. The fish is then packed or canned in dried condition.
4. Sun drying : This inhibits the growth of microorganisms that spoil the fish.
5. Smoke drying : Smoke is prepared by burning woods with less resinous matter. Bacteria are destroyed by the acid content of the smoke. Smoking also give the characteristic colour, taste and odour to fish.
6. Salting: Salt removes the moisture from the fish tissues by osmosis. High salt concentration destroys autolytic enzymes and halts bacterial activity.
7. Canning: Canning involves sealing the food in a container, heat 'sterilising' the sealed unit and cooling it to ambient temperature for subsequent storage.
In simple words: Fish preservation uses methods like chilling, freezing, drying, salting, and canning to prevent spoilage by inhibiting microbial growth and enzyme activity, extending shelf life.

🎯 Exam Tip: Describe multiple preservation methods, explaining the underlying principle (e.g., inhibiting enzymes, removing moisture) for each.

Question 4.Give an account of poultry diseases.
Answer: Various poultry diseases are as follows:
1. Viral diseases - Ranikhet, Bronchitis, Avian influenza (bird flu), etc. Bird flu had serious impact on poultry farming and also caused human infection.
2. Bacterial diseases - Pullorum, Cholera, Typhoid, TB, CRD (chronic respiratory disease), Enteritis, etc.
3. Fungal diseases - Aspergillosis, Favus and Thrush.
4. Parasitic diseases - Lice infection, round worm, caecal worm infections, etc.
5. Protozoan diseases: Coccidiosis.
In simple words: Poultry diseases are categorized into viral (like bird flu), bacterial (like cholera), fungal (like aspergillosis), parasitic (like lice), and protozoan (like coccidiosis), impacting bird health and productivity.

🎯 Exam Tip: Classify poultry diseases by their causative agents and provide at least one specific example for each category.

Question 5.Give an account of mutation breeding with examples.
Answer:
1. Mutations are sudden heritable changes in the genotype.
2. Natural mutations occur at a very slow rate.
3. Natural physical mutagens include exposure to high temperature, high concentration of C02, X-rays, UV rays.
4. Mutations can be induced by using various mutagens.
5. Mutagens cause gene mutations and chromosomal aberrations.
6. Chemical mutagens include nitrous acid, EMS (Ethyl - Methyl - Sulphonate), mustard gas, colchicine, etc.
7. Seedlings or seeds are irradiated by using CO60 or UV bulbs or X-ray machines.
8. The mutated seedlings are then screened for resistance to diseases/pests, high yield, etc.
9. Examples of mutant varieties in different crops are Jagannath (rice), NP 836 (rust resistant wheat variety), Indore-2 (cotton variety resistant to bollworm), Regina-ll (cabbage variety resistant to bacterial rot).
In simple words: Mutation breeding involves inducing genetic changes in crops using mutagens (chemicals or radiation) to create new varieties with desirable traits like disease resistance and high yield.

🎯 Exam Tip: Define mutation breeding, describe the types of mutagens used, outline the process of selecting mutated plants, and provide examples of successful mutant varieties.

Question 6.Describe briefly various steps of plant breeding methods.
Answer: The main steps of the plant breeding program (Hybridization) are as follows:
(1) Collection of variability:
• Germplasm collection is the entire collection of all the diverse alleles for all genes in a given crop.
• Wild species and relatives of the cultivated species having desired traits are collected and preserved.
• Forests and natural reserves are the means of in situ conservation of germplasm.
• Botanical gardens, seed banks, etc. are means of ex situ conservation of germplasm.
(2) Evaluation and selection of parents:
• The collected germplasm is evaluated to identify healthy and vigorous plants with desirable and complementary characters.
• Selected parents are selfed for three to four generations to increase homozygosity.
• Only pure lines are selected, multiplied and used in the hybridization.
(3) Hybridization:
• The variety showing maximum desirable features is selected as female (recurrent) parent and the other variety which lacks good characters found in recurrent parent is selected as male parent (donor).
• The pollen grains from anthers of male parent are artificially dusted over stigmas of emasculated flowers of female parent.
• Hybrid seeds are collected and sown to grow F₁ geneartion.
(4) Selection and Testing of Superior Recombinants:
• The F₁ hybrid plants which are superior to both the parents and having high hybrid vigour, are selected and selfed for few generations to make them homozygous for the said desirable characters.
• This ensures that there is no further segregation of the characters.
(5) Testing, release and commercialization of new cultivars:
• The newly selected lines are evaluated for the productivity and desirable features like disease resistance, pest resistance, quality, etc.
• They are initially grown under controlled conditions of water, fertilizers, etc. and their performance is recorded.
• The selected lines are then grown for at least three generations in natural field, in different agroclimatic zones.
• Finally variety is released as new variety for use by the farmers.
In simple words: Plant breeding involves collecting diverse genetic material, selecting suitable parents, cross-breeding them (hybridization), identifying superior offspring, and then testing and releasing new improved crop varieties.

🎯 Exam Tip: Detail the five main steps of a plant breeding program, explaining the purpose and key activities in each stage.