Solutions-Class-12-Biology-Chapter-11-Enhancement in Food Production-Maharashtra Board

(c) Streptomyces venezuelae

(a) primary treatment

(a) Azotobacter

(a) barley

(b) Saccharomyces

(c) Rhodospirillum

(a) bread

(a) production of hybrids

(c) interspecific hybridization

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.

Rhizobium, Frankia, Pseudomonas striata.

The microbial source of vitamin B₁₂ is Pseudomonas denitrificans.

The microbial source of enzyme invertase is Saccharomyces cerevisiae.

Lactic Acid Bacteria (LAB) check the growth of disease causing microbes and produce vitamin B.

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.

A breed refers to a group of animals that share common characteristics such as appearance, size, and configuration, such as their descent.

Estuary is a place where river meets the sea.

Shellac is the pure form of lac obtained by washing and filtering.

• Homemade food preparations often involve the use of microorganisms, such as Lactobacilli for dhokla and buttermilk.
• Dosa and idlis are made using rice and black gram batter fermented by bacteria like Leuconostoc and Streptococcus.
• Curd is made by inoculating milk with Lactobacillus acidophilus, which causes coagulation and partial digestion of milk protein casein.
• Buttermilk, the acidulated liquid left after churning butter from curd, is the final product.
• 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.

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 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).
• 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 :

• Hydrolysis or solubilization : Anaerobic hydrolyzing bacteria like Clostridium and Pseudomonas hydrolyse carbohydrates into simple sugars, proteins into amino acids and lipids into fatty acids.
• Acidogenesis : Facultative and obligate anaerobic, acidogenic bacteria convert simple organic substances into acids like formic acid, acetic acid, H₂ and CO₂
• Methanogenesis : Anaerobic methanogenic bacteria like Methanobacterium, Methanococcus convert acetate, H₂ and CO₂ into Methane, CO₂ and H₂O and other products.

12 mol CH₃COOH —> 12CH₄ + 12CO₂

4 mol H.COOH —> CH₄ + 3CO₂ + 2H₂O

CO₂ + 4H₂ —> CH₄ + 2H₂O

• Biocontrol agents are the organisms like (bacteria, fungi, viruses and proiozoans) act which are employed for controlling pathogens, pests and weeds.
• They cause the disease to the pest or compete or kill them.
• The use of biocontrol measures greatly reduces use of toxic chemicals and pesticides that are harmful to human beings and also pollute our environment.

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-NPVI Granulovirus-GV) Host : Caterpillars, Gypsy moth, ants and beetles.

Some examples :

• Bacillus thuringiensis (Bt) is a microbial pesticide used to get rid of butterfly,
• Trichoderma fungus is an effective biocontrol agent against soil borne fungal plant pathogens which infect roots and rhizomes.
• Phytophthora palmivora 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.

Enzymes and microbial source :

(i) Invertase  - Saccharomyces cerevisiae.

(ii)  Pectinase - Sclerotinia libertine, Aspergillus niger.

Antibiotics and microbial source :

(i) Penicillin - Penicillium chrysogenum.

(ii) Streptomycin - Streptomyces griseus.

The principles of farm management are as follows :

• Selecting high-yielding breeds.
• Understanding animal feed needs.
• Providing adequate nutritional sources.
• Maintaining environmental cleanliness.
• Veterinary supervision for health maintenance.
• Implementing vaccination programs.
• Developing high-yielding cross-bred varieties.
• Producing and preserving products.
• Distributing and marketing farm produce.

• Fish is a nutritious food and thus is a source of many vitamins, minerals and nutrients.
• Commercial products such as fish oil, fish meal and fertilizers, fish guano, fish glue, isinglass are prepared from fish.
• These by-products are used in paints, soaps, oils and medicines.
• Some organisms like prawns and lobsters have high export value and market price.
• Fish farming and other fishery trades provide job opportunity and self-employment.
• Productivity and national economy is improved through fishery practices.

The four species of honey bees commonly found in India : Apis dorsata (rock bee or wild bee), Apis florea (little bee), Apis mellifera (European bee) and Apis indica (Indian bee).

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.

A : Penicillium chrysogeflum

B : Vinegar (Acetic acid)

C : Fungus

D : Sachharomyces cerevisiae var. ellipsoidis

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) :

• Sewage water pumped into primary sedimentation tank.
• 50-70% suspended solid or organic matter sedimented, 30-40% coliform organisms removed.
• Sewage settled into primary sludge.
• Mechanically operated devices remove primary sludge.
• Dissolved organic matter and micro-organisms removed by secondary treatment.

 (3) Secondary treatment (biological treatment) :

• Secondary treatment involves passing primary effluent into large aeration tanks, where it is mechanically agitated and air is pumped.
• Aerobic bacteria, slime, and fungal hyphae, known as flocs, form mesh-like masses, consuming most organic matter and reducing the Biochemical Oxygen Demand (BOD) of the effluent.

 (4) Tertiary treatment :

• The tertiary treatment process involves reducing BOD in waste water, settling it in a tank, and transferring it to an aeration tank.
• The majority of the activated sludge is then pumped into large anaerobic sludge digesters.
• Anaerobic bacteria grow and digest the bacteria and fungi, releasing gases like methane, hydrogen sulphide, CO₂
• Effluents from these digesters are released in natural water bodies like rivers and streams after chlorination which kills pathogenic bacteria.
• The resulting sludge is then disposed of.

• Lac is a pink resin released by the dermal glands of female lac insects (Trachardia lacca) that hardens when exposed to air and forms lac.
• Lac is a complex compound that includes resin, sugar, water, minerals, and alkaline chemicals.
• Lac insects are colonial in nature and feed on succulent twigs such as ber, peepal, palas, kusum, and babool. These plants are intentionally infected to provide a more consistent and high-quality supply of lac.
• Natural lac is constantly polluted, and the pure form of lac achieved via washing and filtering is known as shellac.
• Lac is used in the production of bangles, toys, woodwork, inks, mirrors, and other products.
• India’s share is 85% of total lac produced in the world.

Fish is a highly perishable commodity. After catching the fish it immediately starts spoilage process. In order to prevent this process, the fish preservation is done.

The different methods of fish preservation are as follows :

• Chilling : This involves covering the fish with layers of ice. Ice is effective for short term preservation. It inhibits the activity of autolytic enzymes.
• 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.
• 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.
• Sun drying : This inhibits the growth of microorganisms that spoil the fish.
• 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.
• Salting : Salt removes the moisture from the fish tissues by osmosis. High salt concentration destroys autolytic enzymes and halts bacterial activity.
• Canning: Canning involves sealing the food in a container, heat ‘sterilising’ the sealed unit and cooling it to ambient temperature for subsequent storage.

Various poultry diseases are as follows :

• Viral diseases : Ranikhet, Bronchitis, Avian influenza (bird flu), etc. Bird flu had serious impact on poultry farming and also caused human infection.
• Bacterial diseases : Pullorum, Cholera, Typhoid, TB, CRD (chronic respiratory disease), Enteritis, etc.
• Fungal diseases : Aspergillosis, Favus and Thrush.
• Parasitic diseases : Lice infection, round worm, caecal worm infections, etc.
• Protozoan diseases : Coccidiosis.

• Mutations are sudden heritable changes in the genotype.
• Natural mutations occur at a very slow rate.
• Natural physical mutagens include exposure to high temperature, high concentration of CO₂, X-rays, UV rays.
• Mutations can be induced by using various mutagens.
• Mutagens cause gene mutations and chromosomal aberrations.
• Chemical mutagens include nitrous acid, EMS (Ethyl - Methyl — Sulphonate), mustard gas, colchicine, etc.
• Seedlings or seeds are irradiated by using CO60 or UV bulbs or X-ray machines.
• The mutated seedlings are then screened for resistance to diseases/ pests, high yield, etc.
• Examples of mutant varieties in different crops are Jagannath (rice), NP 836 (rust resistant wheat variety), Indore-2 (cotton variety resistant to bollworm), Regina-II (cabbage variety resistant to bacterial rot).

The main steps of the plant breeding program (Hybridization) are as follows :

(i) Collection of variability :

• Germplasm collection is the entire collection of all the diverse alleles for all genes in a given crop.
• Preservation of wild species and relatives of cultivated species with desired traits.
• In situ conservation through forests and natural reserves.
• Ex situ conservation through botanical gardens and seed banks.

 (ii) 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.

(iii) 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

(iv) 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.

(v) Testing, release and commercialization of new cultivars :

• Newly selected lines are evaluated for productivity and desirable features like disease and pest resistance.
• They are grown under controlled conditions and recorded.
• After three generations in natural fields, the selected lines are released as new varieties for farmers to use.