Class 12 biology chapter 11 Enhancement of Food Production solutions

Class 12 biology chapter 11 Enhancement of Food Production Textbook solutions

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Q. 1 Multiple Choice Questions.
1. Antibiotic Chloromycetin is obtained from .....................
a. Streptomyces erythreus
b. Penicillium chrysogenum
c. Streptomyces venezuelae
d. Streptomyces griseus

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

3. Which one of the following is free living bacterial biofertilizer?
a. Azotobacter
b. Rhizobium
c. Nostoc
d. Bacillus thuringiensis

4. Most commonly used substrate for 
industrial production of beer is ............. 
a. barley
b. wheat
c. corn
d. sugarcane molasses

5. Ethanol is commercially produced 
through a particular species of ..............
 a. Aspergillus
 b. Saccharomyces
 c. Clostridium
 d. Trichoderma

6. One of the free-living anaerobic nitrogen-fixer is .....................
a. Azotobacter
b. Beijerinckia
c. Rhodospirillum
d. Rhizobium

7. Microorganisms also help in production of food like .................
a. bread
b. alcoholic beverages
c. vegetables
d. pulses

8. MOET technique is used for ............
 a. production of hybrids
 b. inbreeding
 c. outbreeding
 d. outcrossing

9. Mule is the outcome of ..............
 a. inbreeding
 b. artificial insemination
 c. interspecific hybridization
 d. outbreeding

Q. 2 Very Short Answer Questions: 
1. What does make idlies puffy?
Answer : A mixture of rice and urad dal or black lentil makes the idli batter that involves a lot of processes.” “Heat allows the growth of bacteria like yeasts which along with free availability of oxygen and sugar decompose into carbon-dioxide and water. the yeast makes it puffy.

2. Name any two bacterial biofertilizers.
Answer: Azospirillum, Azotobacter, Bacillus, Burkholderia, Enterobacter, Klebsiella, and Pseudomonas, but some of these genera include endophytic species as well.

3. What is the microbial source of vitamin B12?
Answer : B12 is synthesized by only certain bacteria and archaeon, but not by plants or animals. The synthesized B12 is transferred and accumulated in animal tissues, even in certain plant tissues via microbial interaction. Meats and milks of herbivorous ruminant animals are good sources of B12 for humans.

4. What is the microbial source of enzyme Invertase?
Answer : Invertase is produced by different strains of microorganisms, Saccharomyces cerevisiae commonly called Baker's yeast is the primary strain used for the production of Invertase commercially. They are found in wild growing on the skin of grapes, oranges and other fruits.

5. Milk start to coagulate when Lactic Acid Bacteria (LAB) is added to warm milk as a starter. Mention any two other benefits of LAB.
Answer : Besides curdling of milk the lactic acid bacteria are beneficial to us in following ways : (a) They improve the nutritional quality of curd by producing Vitamin B12. (b) They help in inhibiting the development of disease causing microorganism in the gult.

6. Name the enzyme produced by 
Streptococcus bacterium. Explain 
importance in medical sciences.
Answer : The enzyme produced by streptococcus bacterium is streptokinase. It is a bioactive molecule. It is used as a 'clot buster' for removing clots from the blood vessels of patients who have undergone myocardial infraction leading to heart attack.

7. What is breed?
Answer : A breed is a specific group of domestic animals having homogeneous appearance (phenotype), homogeneous behavior, and/or other characteristics that distinguish it from other organisms of the same species.

8. Define estuary.
Answer : An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea.

9. What is shellac?
Answer : Shellac is a resin secreted by the female lac bug on trees in the forests of India and Thailand.

Q. 3 Short Answer Questions.
1. Many microbes are used at home during preparation of food items. Comment on such useful ones with examples.
Answer : Many microbes are used at home during preparation of food items. Comment on such useful ones with examples.
Propiobacterium shermanii - Used in preparation Swiss Cheese.
P.roquefortii - Roquefort Cheese.
Lactobacillus - Curd Preparation.
Acetobacter aceti - Acetic Acid.

2. What is biogas? Write in brief about the production process.
Answer : Biogas is the mixture of gases produced by the breakdown of organic matter in the absence of oxygen (anaerobically), primarily consisting of methane and carbon dioxide.

A typical biogas plant using cattle dung as a raw material, consists of digester and gas holder. Digester is made up of concrete bricks and cement, or steel. There is cylindrical gas holder or gas tank above it to collect gases. Digester has a side opening (charge pit) into which raw material as cow dung is fed. The digester is partly burried in the soil.

Anaerobic digestion involves in three 
processes :
i. Hydrolysis or solublization : In initial
stage raw material (cattle dung) is mixed
with water in equal proportion to make
slurry which is then fed into the digester.
Here anaerobic hydrolytic bacteria (e.g.
Clostridium, Pseudomonas) hydrolyse carbohydrates into simple sugars, proteins into amino acids and lipids into fatty acids.

ii. Acidogenesis : In this stage, facultative
anaerobic, acidogenic bacteria and obligate
anaerobic organisms, convert simple
organic material into acids like formic
acid, acetic acid, H2 and CO2

iii. Methanogenesis :
This is last stage in which anaerobic
Methanogenic bacteria like Methanobacterium, bMethanococcus convert acetate, H2 and CO2 into Methane, CO2 and H2O and other products.

3. Write a note on biocontrol agents.
Answer: Biological control or biocontrol is a method of controlling pests such as insects, mites, weeds and plant diseases using other organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms, but typically also involves an active human management role.

4. Name any two enzymes and antibiotics with their microbial source.
Answer :
1. Chloromycetin -Streptomyces venezuelae
2. Erythromycin- Streptomyces erythreus
3. Penicillin - Penicillium chrysogenum
4. Streptomycin- Streptomyces griseus

5. Write priciples of farm management.
Answer : The main elements of the economic principles considered in agricultural farm management are comparative advantage, diminishing returns, substitution, cost analysis, opportunity cost, enterprise choice and goal trade-off.

6. Give economic importance of fishery.
Answer : Fishes are one of the most important group of vertebrates serving as food for human. They possess a great economic, nutritional, medicinal, industrial, aesthetic and religious values as well as providing employment for millions of people in the world.

7. Enlist the species of honey bee mentioning their specific uses.
Answer : The only domesticated species of honey bee are A. mellifera and A. cerana, and they are often maintained, fed, and transported by beekeepers. In Japan, where mellifera is vulnerable to local hornets and disease, the Japanese honey bee a. cerana japonica is used in its place.

8. What are A, B, C and D in the table given 
below : 
Answer :
A- Penicillium chrysogenum

B- vinegar, wines, and beers.

C- Fungus

D- Saccharomyces cerevisiae

Q. 4 Long Answer Questions.
1. Explain the process of sewage water 
treatment before it can be discharged 
into natural bodies. Why this treatment is essential?
Answer : Before waste water is made available for human use, it has to be treated properly, so as to remove organic matter, inorganic salts and pathogens as well.

Sewage treatment process 
includes four basic steps as follows:
1. Preliminary Treatment:
The preliminary treatment includes
Screening and Grit Chamber.
i. Screening : Sewage and waste water
contains plenty of suspended, floating
materials, coarse and solid particles along
with dissolved substances. The suspended
objects are filtered and removed. This is
done in screening chambers. The sewage
is passed through screens or net in the
chambers. Larger suspended or floating
objects are held back in the screening.

2. Primary treatment (physical treatment):
After the preliminary treatment, the
sewage water is pumped into the primary
sedimentation tank. The sedimentation of
suspended solid or organic matter occurs in this tank. About 50-70% of the solids settle
down. There is reduction of about 30-40% (in number) of coliform organisms. The organic matter which is settled down, is called primary sludge which is removed by mechanically operated devices.

3. Secondary treatment (biological 
The primary effluent is passed into large
aeration tanks. Here it is constantly agitated mechanically and air is pumped into it. Aerobic bacteria grow vigourously and form flocs.Flocs are the masses of bacteria held together by slime and fungal hyphae to form mesh like masses. These aerobic microbes consume the major part of the organic matter present in the effluent, as they grow. Due to this BOD (Biochemical Oxygen Demand) of the effluent
is significantly reduced.

4. Tertiary treatment:
Once the BOD of waste water is reduced, it
is passed into a settling tank. Here the bacterial flocs are allowed to sediment. The sediment is now called activated sludge. Small part of this is passed back in to aeration tank and the major part is pumped in to large tanks called anaerobic sludge digesters. In these tanks, anaerobic bacteria grow and digest the bacteria and fungi in the sludge. During this anaerobic
digestion, gases such as methane, hydrogen
sulphide, CO2, etc. are produced. Effluents
from these plants (digester) after chlorination, are released in natural water bodies like rivers and streams. Chlorination kills pathogenic bacteria. Digested Sludge is then disposed.

2. Write a note on lac culture.
Answer : Lac is produced by an insect Trachardia lacca, which is quite small in size and colonial in habit. Resin like substance is produced by Dermal glands of female lac insect. Insect feeds on succulent twigs of certain plants like ber, peeple, palas, kusum, babool, etc and secretes
pink coloured resin, that hardens on coming in contact with air forming lac. It is produced on a large scale all over India.
Lac is a complex substance having large
amount of resin together with sugar, water, minerals and alkaline substances.
Natural lac is always contaminated.
Shellac is pure form of lac obtained by washing and filtering. Lac insect is a native of India and our share is 85 % of total lac produced in the world. Products of lac play a vital role in the economy of the farmers. Lac is used in bangles, toys, woodwork, inks, mirrors, etc

3. Describe various methods of fish 
Answer : After catching the fishes, fish spoilage is prevented by different preservation methods like chilling, freezing, freeze drying, sun drying, smoke drying, salting and canning. In addition to the source as nutritious food, fish yield a number of by-products which are of
commercial value. They are fish oil, fish meal, fertilizers, fish guano, fish glue and isinglass. These by-products are widely used in paints, soaps, oils, and medicine. Prawns and Lobsters have market value all over the world..

4. Give an account of poultry diseases.
Answer : Management of layers, requires purchase of high yielding chicken, well ventilated farms, proper feed, debeaking, lighting, waterer, sanitation, culling and vaccination. Management of broilers requires selection of breed, housing, temperature, ventilation, lighting, floor space and broiler feed. Different
types of poultry diseases are:

i. Viral diseases like Ranikhet, Bronchitis,
Avian influenza (bird flu), etc. Few years
back, bird flu have seriously influenced poultry farming and human infection too.

ii. Bacterial diseases mainly includes
Pullorum, Cholera, Typhoid, TB, CRD (chronic respiratory disease), Enteritis, etc.

iii. Fungal diseases are Aspergillosis, Favus and Thrush.

iv. Parasitic diseases include lice infection, round worm, caecal worm infections, etc.

v. Protozoan diseases e.g. Coccidiosis is a
protozoan disease.

5. Give an account of mutation breeding 
with examples.
Answer : Mutation Breeding :
Mutation is sudden heritable change in
the genotype, caused naturally. It can also be induced by application of chemical mutagens. Natural (physical) mutagens are : High tem-perature, high concentration of CO2, X rays, UV rays.

Chemical mutagens are : Nitrous acid, EMS
(Ethyl- Methyl- Sulphonate), Mustard gas,
Colchicine, etc. Seedlings or seeds are irradiated by CO-60, exposed to UV bulbs, X ray machines, etc.  Mutagens cause gene mutations and chromosomal aberrations. The treated seedlings are then screened for resistance to diseases/ pests, high yield, etc. e.g. Jagannath. variety of rice, NP 836 variety of wheat (rust resistant), Indore-2 variety of cotton (resistant to bollworm), Regina-II variety of cabbage (resistant to bacterial rot), etc.

6. Describe briefly various steps of plant 
breeding methods.
Answer : The improvement or purposeful
manipulation in the heredity of crops and the production of new superior varieties of existing crop plants, constitute what is called plant

The main steps of the plant breeding 
program (Hybridization) are as follows :
1. Collection of Variability :
Wild species and relatives of the cultivated
species having desired traits, should be collected and preserved. The entire collection having all the diverse alleles (i.e. variations) for all genes in a given crop, is called germplasm collection. Variations are useful in the selection.
Germplasm conservation can be done in
following ways-
• In situ conservation : It can be done with
the help of forests and Natural Reserves.
• Ex situ conservation : It is done through
botanical gardens, seed banks, etc.

2. Evaluation and Selection of Parents :
It is an important and essential step. The
collected germplasm is evaluated (screened) to identify plants with desirable characters. The selected parents must be healthy, vigorous and should show desirable but complementary
features. The selected parents are selfed for three to four generations to make them pure or homozygous. It is made sure that 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 one as male parent (donor) which
lacks good characters found in recurrent parent.The pollen grains from anthers of male parent are collected and then artificially dusted over stigmas of emasculated flowers of female

4. Selection and Testing of Superior 
Recombinants :
The F1 hybrid plants showing superiority
over both the parents and having high hybrid-vigour, are selected. Such hybrids are then selfed for few generations to make them homozygous for the said desirable characters till there is a state of uniformity, so that the characters will not segeregate further.

5. Testing, Release and Commercialization of New Cultivars :
The newly selected lines are evaluated
for the productivity and other features like
disease resistance, pest resistance, quality, etc. Initially, these plants are grown under controlled conditions of water, fertilizers, etc