Agriculture 2010 SOLVED PAPER

Part I

Q.1. Select the best option/answer and fill in the appropriate box on the Answer Sheet. (20)

(i) Wheat inflorescence is called as:
(a) Spike (b) Panicle (c) Spadix (d) Cymose (e) None of these

(ii) Soil structure can be improved with the addition of:
(a) Chemical fertilizer (b) Gypsum (c) Lime (d) Organic matter (e) None of these

(iii) Humidity is measured by means of:
(a) Luxmeter
(b) Anemometer (c) Psychrometer
(d) Thermometer
(e) None of these (Hygrometer)

(iv) When soil surface is protected/covered with residue of a crop, the practice is called?
(a) Sheet erosion
(b) Nitrogen fixation
(c) Tillage
(d) Mulching
(e) None of these

(v) Which of the following is not a fruit?
(a) Tomato
(b) Potato
(c) Pumpkin
(d) Melon
(e) None of these

(vi) Which one of the following is a good source of protein?
(a) Wheat
(b) Maize
(c) Pulses
(d) Meat
(e) None of these

(vii) The vector of cotton leaf curl virus in Pakistan is considered as:
(a) Jassid
(b) Aphid
(c) Pink boll worm
(d) White fly
(e) None of these

(viii) In genetics the appearance of an attribute of living organism is termed as:
(a) Dominant
(b) Phenotype
(c) Recessive
(d) Genotype
(e) None of these

(ix) Rhizobium belongs to:
(a) Nitrogen fixing bacteria
(b) Amonifying bacteria
(c) Nitrifying bactyeria
(d) Denitrifying bacteria
(e) None of these

(x) In DNA, adenine always pairs with:
(a) Guanine
(b) Thymine
(c) Uracil
(d) Cytosine
(e) None of these

(xi) Insects have:
(a) 4 legs and 2 wings
(b) 8 legs and 4 wing
(c) 6 legs and 4 wings
(d) 4 legs and 4 wings
(e) None of these

(xii) Tikka disease is major pathogenic threat in:
(a) Wheat
(b) Apple
(c) Sorghum
(d) Groundnut
(e) None of these

(xiii) Food and Agriculture Organization (FAO) has its headquarters in:
(a) Washington
(b) Geneva
(c) Rome
(d) Paris
(e) None of these

(xiv) Soil salinity can be rectified with:
(a) Urea
(b) Ammonium Sulphate
(c) Sodium Chloride
(d) Gypsum
(e) None of these

(xv) Safflower is an:
(a) Oil producing plant
(b) Ornamental plant
(c) Leguminous plant
(d) Fibre producing plant
(e) None of these

(xvi) Banana fruit is classified in the category of:
(a) Berry
(b) Pomes
(c) Stone fruit
(d) Drupe
(e) None of these

(xvii) Ploidy level of maize plant is:
(a) Monoploid (b) Diploid (c) Haploid (d) Tetraploid (e) None of these

(xviii) Gypsum is rich source of:
(a) Calcium + Zinc (b) Calcium + Potassium (c) Calcium + Sulpher (d) Calcium + Nitrogen
(e) None of these

(xix) Gossypium hirsutum is the botanical name of:
(a) Rice (b) Maize (c) Sugarcane (d) Cotton (e) None of these

(xx) Olericulture is the study dealing with:
(a) Honey bee
(b) Rearing of silk worms
(c) Vegetable production
(d) Growing ornamental flowers
(e) None of the above

Part II

Q.2 Price control mechanism of some major agricultural commodities has failed in the country in the near past. Identify the main bottlenecks and suggest necessary measures to strengthen the existing marketing system.

In free market economy prices are controlled by demand and supply mechanism. If the demand for a commodity is higher than supply its price will go up and the vice versa. This means let on its own the market forces can decide its course.But in many economies, governments too intervene to keep the prices in affordable limits by setting minimum and maximum support price mechanisms.Minimum support price is announced to protect the interests of growers, as whenever the demand surpasses the supply the prices increase and it ultimately benefits the growers.Similarly, setting maximum price of a commodity is set in a situation when the government intends to prevent prices going above a certain level. In case the maximum price is lower than the demand, it will fuel the demand and lead to shortage of a certain commodity.Wheat, cotton and tobacco are some of the commodities whose minimum support price is determined on yearly basis here.While for unpacked edibles, including fruit, vegetable, fresh meat etc the prices are determined by following the maximum price concept. There is no price control mechanism for the packed and processed food items at all.District administrations try to control the prices of commodities through price control committees that are also represented by the shopkeepers and grain dealers. Once the prices are set, the district functionaries, under their assigned mandate, check the observance of the price list in the market. They penalise the shopkeepers in case they are found overcharging or hoarding a commodity for creating artificial shortage or manipulating the prices.In theory, this sounds perfect that the government sets the prices in consultation with the market players and then makes sure nobody violates the maximum price schedule, but practically, it doesn’t yield the intended results.The biggest problem with the current price control system is that it is focused only on the retail market, as there is no check on the middlemen who manipulates prices of commodities being brought from farm to market. The middlemen, blessed with black money, manoeuver prices to their advantage before a commodity reaches the wholesale market.In the wholesale market, the prices are set on the demand and supply mechanism and from the very beginning the prices are determined on the higher side, which leaves little margin for the district administrations to keep the prices in affordable limits.For instance, reports of district functionaries raiding markets and rounding up profiteers are daily reported by media, but even then there is no end to the spiral of prices.This is mainly because the government doesn’t have any sort of check on middlemen.Lack of authentic data about the demand and supply of commodity is also a big issue that keeps the prices going up on daily basis. There is no authentic and verifiable data available about the actual population and the annual yield of various edible commodities.One day the government will allow exporting wheat after having its bumper crop, a few months later it will start importing the same commodity on higher prices when its shortage is felt. This has happened quite frequently.The population explosion is also contributing to the prices spiral. When the number of people grows the production is depleted that put extra pressure on the markets and this is what is happening in our case.The Afghan consumer market is also relying on the commodities produced in Pakistan. The government for certain political reasons is required to allow the cross-border movement of various commodities, but in the entire exercise the needs of local market are overlooked that causes increase of prices here. Then, there is also an element of corruption involved in this cross-border trade, as the permits allocated for export of wheat flour, sugar and livestock are manipulated for sending consignments many times above the assigned targets.Checking prices of commodities during the holy month of Ramazan has become more of a seasonal job of the local administrators that is undertaken to demonstrate that the state cares for its people. But in fact such cosmetic arrangements are not addressing the root causes of the problem and keep the consumers suffering.

Q.3 Biotic stresses are the matter of great concern in agricultural crop production . Give a comprehensive approach of various pathways to protect the crops from these threats.

Biotic Stress is stress that occurs as a result of damage done to plants by other living organisms, such as bacteria, viruses, fungi, parasites, beneficial and harmful insects, weeds, and cultivated or native plants.
TRANSGENIC PLANTS WITH BENEFICIAL TRAITS
During the last decades, a tremendous progress has been made in the development of transgenic plants using the various techniques of genetic engineering. The plants, in which a functional foreign gene has been incorporated by any biotechnological methods that generally are not present in the plant, are called transgenic plants. As per estimates recorded in 2002, transgenic crops are cultivated world-wide on about 148 million acres (587 million hectares) land by about 5.5 million farmers. Transgenic plants have many beneficial traits like insect resistance, herbicide tolerance, delayed fruit ripening, improved oil quality, weed control etc. Some of the commercially grown transgenic plants in developed countries are: “Roundup Ready” soybean, ‘Freedom II squash’, ‘High- lauric’ rapeseed (canola), ‘Flavr Savr’ and ‘Endless Summer’ tomatoes. During 1995, full registration was granted to genetically engineered Bt gene containing insect resistant ‘New Leaf’ (potato), ‘Maximizer’ (corn), ‘BollGard’ (cotton) in USA. Some of the traits introduced in these transgenic plants are as follows:
Stress tolerance Biotechnology strategies are being developed to overcome problems caused due to biotic stresses (viral, bacterial infections, pests and weeds) and abiotic stresses (physical actors such as temperature, humidity, salinity etc).

Abiotic stress tolerance The plants show their abiotic stress response reactions by the production of stress related osmolytes like sugars (e.g. trehalose and fructans), sugar alcohols (e.g. mannitol), amino acids (e.g. proline, glycine, betaine) and certain proteins (e.g. antifreeze proteins). Transgenic plants have been produced which over express the genes for one or more of the above mentioned compounds. Such plants show increased tolerance to environmental stresses. Resistance to abiotic stresses includes stress induced by herbicides, temperature (heat, chilling, freezing), drought, salinity, ozone and intense light. These environmental stresses result in the destruction, deterioration of crop plants which leads to low crop productivity. Several strategies have been used and developed to build ressitance in the plants against these stresses.

Herbicide tolerance Weeds are unwanted plants which decrease the crop yields and by competing with crop plants for light, water and nutrients. Several biotechnological strategies for weed control are being used e.g. the over-production of herbicide target enzyme (usually in the chloroplast) in the plant which makes the plant insensitive to the herbicide. This is done by the introduction of a modified gene that encodes for a resistant form of the enzyme targeted by the herbicide in weeds and crop plants. Roundup Ready crop plants tolerant to herbicide-Roundup, is already being used commercially.
The biological manipulations using genetic engineering to develop herbicide resistant plants are: (a) over-expression of the target protein by integrating multiple copies of the gene or by using a strong promoter., (b) enhancing the plant detoxification system which helps in reducing the effect of herbicide., (c) detoxifying the herbicide by using a foreign gene., and (d) modification of the target protein by mutation.
Some of the examples are: Glyphosate resistance - Glyphosate is a glycine derivative and is a herbicide which is found to be effective against the 76 of the world’s worst 78 weeds. It kills the plant by being the competitive inhibitor of the enzyme 5-enoyl-pyruvylshikimate 3- phosphate synthase (EPSPS) in the shikimic acid pathway. Due to it’s structural similarity with the substrate phosphoenol pyruvate, glyphosate binds more tightly with EPSPS and thus blocks the shikimic acid pathway.
Certain strategies were used to provide glyphosate resistance to plants.
(a) It was found that EPSPS gene was overexpressed in Petunia due to gene amplification. EPSPS gene was isolated from Petunia and introduced in to the other plants. These plants could tolerate glyphosate at a dose of 2- 4 times higher than that required to kill wild type plants. (a) By using mutant EPSPS genes- A single base substitution from C to T resulted in the change of an amino acid from proline to serine in EPSPS. The modified enzyme cannot bind to glyphosate and thus provides resistance.
(b) The detoxification of glyphosate by introducing the gene (isolated from soil organism- Ochrobactrum anthropi) encoding for glyphosate oxidase into crop plants. The enzyme glyphosate oxidase converts glyphosate to glyoxylate and aminomethylphosponic acid. The transgenic plants exhibited very good glyphosate ressitance in the field.
Another example is of Phosphinothricin resistance
Phosphinothricin is a broad spectrum herbicide and is effective against broad-leafed weeds. It acts as a competitive inhibitor of the enzyme glutamine synthase which results in the inhibition of the enzyme glutamine synthase and accumulation of ammonia and finally the death of the plant. The disturbace in the glutamine synthesis also inhibits the photosynthetic activity.
The enzyme phosphinothricin acetyl transferase ( which was first observed in Streptomyces sp in natural detoxifying mechanism against phosphinothricin) acetylates phosphinothricin, and thus inactivates the herbicide. The gene encoding for phosphinothricin acetyl transferase (bar gene) was introduced in transgenic maize and oil seed rape to provide resistance against phosphinothricin.
Other abiotic stresses The abiotic stresses due to temperature, drought, and salinity are collectively also known as water deficit stresses. The plants produce osmolytes or osmoprotectants to overcome the osmotic stress. The attempts are on to use genetic engineering strategies to increase the production of osmoprotectants in the plants. The biosynthetic pathways for the production of many osmoprotectants have been established and genes coding the key enzymes have been isolated. E.g. Glycine betaine is a cellular osmolyte which is produced by the participation of a number of key enzymes like choline dehydrogenase, choline monooxygenase etc. The choline oxidase gene from Arthrobacter sp. was used to produce transgenic rice with high levels of glycine betaine giving tolerance against water deficit stress.
Scientists also developed cold-tolerant genes (around 20) in Arabidopsis when this plant was gradually exposed to slowly declining temperature. By introducing the coordinating gene (it encodes a protein which acts as transcription factor for regulating the expression of cold tolerant genes), expression of cold tolerant genes was triggered giving protection to the plants against the cold temperatures.
Insect resistance A variety of insects, mites and nematodes significantly reduce the yield and quality of the crop plants. The conventional method is to use synthetic pesticides, which also have severe effects on human health and environment. The transgenic technology uses an innovative and eco-friendly method to improve pest control management.About 40 genes obtained from microorganisms of higher plants and animals have been used to provide insect resistance in crop plants The first genes available for genetic engineering of crop plants for pest resistance were Cry genes (popularly known as Bt genes) from a bacterium Bacillus thuringiensis. These are specific to particular group of insect pests, and are not harmful to other useful insects like butter flies and silk worms. Transgenic crops with Bt genes (e.g. cotton, rice, maize, potato, tomato, brinjal, cauliflower, cabbage, etc.) have been developed. This has proved to be an effective way of controlling the insect pests and has reduced the pesticide use. The most notable example is Bt cotton (which contains CrylAc gene) that is resistant to a notorious insect pest Bollworm (Helicoperpa armigera).. There are certain other insect resistant genes from other microorganisms which have been used for this purpose. Isopentenyl transferase gene from Agrobacterium tumefaciens has been introduced into tobacco and tomato. The transenic plants with this transgene were found to reduce the leaf consumption by tobacco hornworm and decrease the survival of peach potato aphid. Certain genes from higher plants were also found to result in the synthesis of products possessing insecticidal activity. One of the examples is the Cowpea trypsin inhibitor gene (CpTi) which was introduced into tobacco, potato, and oilseed rape for develping transgenic plants. Earlier it was observed that the wild species of cowpea plants growing in Africa were resistant to attack by a wide range of insects. It was observed that the insecticidal protein was a trypsin inhibitor that was capable of destroying insects belonging to the orders Lepidoptera, Orthaptera etc. Cowpea trypsin inhibitor (CpTi) has no effect on mammalian trypsin, hence it is non-toxic to mammals.
Virus resistance There are several strategies for engineering plants for viral resistance, and these utilizes the genes from virus itself (e.g. the viral coat protein gene). The virus-derived resistance has given promising results in a number of crop plants such as tobacco, tomato, potato, alfalfa, and papaya. The induction of virus resistance is done by employing virus-encoded genes-virus coat proteins, movement proteins, transmission proteins, satellite RNa, antisense RNAs, and ribozymes. The virus coat protein-mediated approach is the most successful one to provide virus resistance to plants. It was in 1986, transgenic tobacco plants expressing tobacco mosaic virus (TMV) coat protein gene were first developed. These plants exhibited high levels of resistance to TMV.
The transgenic plant providing coat protein-mediated resistance to virus are rice, potato, peanut, sugar beet, alfalfa etc. The viruses that have been used include alfalfa mosaic virus (AIMV), cucumber mosaic virus (CMV), potato virus X (PVX) , potato virus Y (PVY) etc.
Resistance against Fungal and bacterial infections As a defense strategy against the invading pathogens (fungi and bacteria) the plants accumulate low molecular weight proteins which are collectively known as pathogenesis-related (PR) proteins.
Several transgenic crop plants with increased resistance to fungal pathogens are being raised with genes coding for the different compounds. One of the examples is the Glucanase enzyme that degrades the cell wall of many fungi. The most widely used glucanase is beta-1,4-glucanase. The gene encoding for beta-1,4 glucanase has been isolated from barley, introduced, and expressed in transgenic tobacco plants. This gene provided good protection against soil-borne fungal pathogen Rhizoctonia solani.
Lysozyme degrades chitin and peptidoglycan of cell wall, and in this way fungal infection can be reduced. Transgenic potato plants with lysozyme gene providing resistance to Eswinia carotovora have been developed.

Delayed fruit ripening The gas hormone, ethylene regulates the ripening of fruits, therefore, ripening can be slowed down by blocking or reducing ethylene production. This can be achieved by introducing ethylene forming gene(s) in a way that will suppress its own expression in the crop plant. Such fruits ripen very slowly (however, they can be ripen by ethylene application) and this helps in exporting the fruits to longer distances without spoilage due to longer-shelf life.
The most common example is the 'Flavr Savr' transgenic tomatoes, which were commercialized in U.S.A in 1994. The main strategy used was the antisense RNA approach. In the normal tomato plant, the PG gene (for the enzyme polygalacturonase) encodes a normal mRNA that produces the enzyme polygalacturonase which is involved in the fruit ripening. The complimentary DNA of PG encodes for antisense mRNA, which is complimentary to normal (sense) mRNA. The hybridization between the sense and antisnse mRNAs renders the sense mRNA ineffective. Consequently, polygalacturonase is not produced causing delay in the fruit ripening. Similarly strategies have been developed to block the ethylene biosynthesis thereby reducing the fruit ripening. E.g. transgenic plants with antisense gene of ACC oxidase (an enzyme involved in the biosynthetic process of ethylene) have been developed. In these plants, production of ethylene was reduced by about 97% with a significant delay in the fruit ripening.
The bacterial gene encoding ACC deaminase (an enzyme that acts on ACC and removes amino group) has been transferred and expressed in tomato plants which showed 90% inhibition in the ethylene biosynthesis.
Male Sterility The plants may inherit male sterility either from the nucleus or cytoplasm. It is possible to introduce male sterility through genetic manipulations while the female plants maintain fertility. In tobacco plants, these are created by introducing a gene coding for an enzyme (barnase, which is a RNA hydrolyzing enzyme) that inhibits pollen formation. This gene is expressed specifically in the tapetal cells of anther using tapetal specific promoter TA29 to restrict its activity only to the cells involved in pollen production. The restoration of male fertility is done by introducing another gene barstar that suppresses the activity of barnase at the onset of the breeding season. By using this approach, transgenic plants of tobacco, cauliflower, cotton, tomato, corn, lettuce etc. with male sterility have been developed.
Q.4 Discuss the causes of soil salinity and water-logging in irrigated agriculture. Suggest appropriate recommendations to reclaim saline sodic soils.

The main causes of soil salinity and water logging in Pakistan are as under :-
1) High water table.
2) Hot dry climate.
3) Inadequate drainage.
4) Inadequate irrigation supplies.
5) Failure to give closures in the irrigation supplies during periods of no demand.
6) Use of chemical amendments for sodic and saline-sodic soils.

Following are some of its remedies:-
1) Leaching the saline soil water from the root zone with waters of lower salt concentration.
2) Effective drainage is required.
3) Vertical drainage. (1960)
4) Horizental sub surface (tile) drainage. (1978)
5) Suitable disposal arrangements required.
6) Donot use gravity flow disposal .
7) Redesign the concept of surface drainage.

Q.5 Narrate the modern techniques of genetics regarding crop involvement. Discuss the prospects of new technologies to have the possibilities of another green revolution

Genetic Engineering Genetically Modified Organisms (GMO) are organisms whose genetic material has been altered by genetic engineering techniques generally known as recombinant DNA technology. Genetic engineering has expanded the genes available to breeders to utilize in creating desired germlines for new crops.
The Plasmid Method
The first technique of genetic engineering, the plasmid method, is the most familiar technique of the three, and is generally used for altering microorganisms such as bacteria. In the plasmid method, a small ring of DNA called a plasmid (generally found in bacteria) is placed in a container with special restriction enzymes that cut the DNA at a certain recognizable sequence. The same enzyme is then used to treat the DNA sequence to be engineered into the bacteria; this procedure creates "sticky ends" that will fuse together if given the opportunity.
Next, the two separate cut-up DNA sequences are introduced into the same container, where the sticky ends allow them to fuse, thus forming a ring of DNA with additional content. new enzymes are added to help cement the new linkages, and the culture is then separated by molecular weight. Those molecules that weigh the most have successfully incorporated the new DNA, and they are to be preserved.
The next step involves adding the newly formed plasmids to a culture of live bacteria with known genomes, some of which will take up the free-floating plasmids and begin to express them. In general, the DNA introduced into the plasmid will include not only instructions for making a protein, but also antibiotic-resistance genes. These resistance genes can then be used to separate the bacteria which have taken up the plasmid from those that have not. The scientist simply adds the appropriate antibiotic, and the survivors are virtually guaranteed (barring spontaneous mutations) to possess the new genes.
Next, the scientist allows the successfully altered bacteria to grow and reproduce. They can now be used in experiments or put to work in industry. Furthermore, the bacteria can be allowed to evolve on their own, with a "selection pressure" provided by the scientist for producing more protein. Because of the power of natural selection, the bacteria produced after many generations will outperform the best of the early generations.
Many people strongly object to the plasmid method of genetic engineering because they fear that the engineered plasmids will be transferred into other bacteria which would cause problems if they expressed the gene. Lateral gene transfer of this type is indeed quite common in bacteria, but in general the bacteria engineered by this method do not come in contact with natural bacteria except in controlled laboratory conditions. Those bacteria that will be used in the wild - for example, those that could clean up oil spills - are generally released for a specific purpose and in a specific area, and they are carefully supervised by scientists.
The Vector Method
The second method of genetic engineering is called the vector method. It is similar to the plasmid method, but its products are inserted directly into the genome via a viral vector. The preliminary steps are almost exactly the same: cut the viral DNA and the DNA to be inserted with the same enzyme, combine the two DNA sequences, and separate those that fuse successfully. The only major difference is that portions of the viral DNA, such as those that cause its virulence, must first be removed or the organism to be re-engineered would become ill. This does yield an advantage - removal of large portions of the viral genome allows additional "space" in which to insert new genes.
Once the new viral genomes have been created, they are allowed to synthesize protein coats and then reproduce. Then the viruses are released into the target organism or a specific cellular subset (for example, they may be released into a bacterium via a bacteriophage, or into human lung cells as is hoped can be done for cystic fibrosis patients). The virus infects the target cells, inserting its genome - with the newly engineered portion - into the genome of the target cell, which then begins to express the new sequence.
With vectors as well, marker genes such as genes for antibiotic resistance are often used, giving scientists the ability to test for successful uptake and expression of the new genes. Once again, the engineered organisms can then be used in experiments or in industry. This technique is also being studied as a possible way to cure genetic diseases (see Genetic Engineering Debates).
Many people object to this type of genetic engineering as well, citing the unpredictability of the insertion of the new DNA. This could interfere with existing genes' function. In addition, many people are uncomfortable with the idea of deliberately infecting someone with a virus, even a disabled one.
The Biolistic Method
The biolistic method, also known as the gene-gun method, is a technique that is most commonly used in engineering plants - for example, when trying to add pesticide resistance to a crop. In this technique, pellets of metal (usually tungsten) coated with the desirable DNA are fired at plant cells. Those cells that take up the DNA (again, this is confirmed with a marker gene) are then allowed to grow into new plants, and may also be cloned to produce more genetically identical crop. Though this technique has less finesse than the others, it has proven quite effective in plant engineering.
Objections to this method arise for many of the same reasons: the DNA could be inserted in a working gene, and the newly inserted gene might be transferred to wild plants. Additionally, this technique is commonly opposed because of its association with genetically modified foods, which many people dislike.
Gene cloning
A fragment of DNA, containing a single gene or a number of genes, can be inserted into a vector that can be propagated within another cell. A vector is a section of DNA that can incorporate another DNA fragment without losing the capacity for self-replication, and a vector containing an additional DNA fragment is known as a hybrid vector. If the fragment of DNA includes one or more genes the process is referred to as gene cloning.
 Plasmid vectors are modified forms of the circular extra-chromosomal DNA molecules found in bacteria, which have been engineered to contain restriction sites and marker genes (to allow the detection of bacterial cells that contain the plasmid). The bacterial artificial chromosome (BAC), a vector based on the naturally occurring F-plasmid found in the bacterium Escherichia coli, is used to clone relatively large segments of DNA.
 Lamda phage vectors are recombinant viruses, containing the phage chromosome plus inserted 'foreign' DNA. In general, phage vectors can carry larger DNA sequences than plasmid vectors.
 Cosmids are artificially constructed cloning vectors, produced by combining plasmids with sections of the lambda phage chromosome. The resultant cosmid can be packed into the phage body for transmission, and use the plasmid genes to direct its replication within the host cell.
 Expression vectors are vectors - plasmid or phage - that include regulatory sequences necessary for the transcription and translation of the cloned gene. The aim is to make as many copies of the protein coded by the gene as possible within the host cell.
The host cell then copies the cloned DNA using its own replication mechanisms. A variety of cell types are used a hosts, including bacteria, yeast cells and mammalian cells.
Polymerase chain reaction (PCR)
Another way of making many copies of a specific section of DNA, without the need for vectors or host cells, is through a polymerase chain reaction (PCR). The DNA to be copied - the template DNA - is mixed with two 20 base pair primers complementary to the end of the template DNA, nucleotides, and a version of DNA polymerase known as Taq polymerase. (This enzyme is stable under high temperatures, and is obtained from the thermophilic bacterium Thermus aquaticus.) The process involves the repetition of three steps:
1. denaturation, which separates the two nucleotide strands of the DNA molecule
2. primer annealing, in which the primers bind to the single-stranded DNA
3. extension, in which nucleotides are added to the primers - in the 5' to 3' direction - to form a double-stranded copy of the target DNA
Each cycle takes about a few minutes, so repeated cycles can produce large amounts of a specific DNA sequence in hours rather than days. However, some details about the nucleotide sequence to be copied must be known in advance, and the technique is sensitive to small amounts of contamination.
Gene libraries
A gene library is a large collection of cloned DNA sequences from a single genome. Agenomic library, in theory, would contain at least one copy of every sequence in an organism's genome. To investigate the structure of a given chromosome, or to clone specific genes, libraries may be prepared from a subset of the entire genome (for example, a single chromosome). The first step is to break up, or 'fractionate', the genome using physical methods or restriction enzymes. The fragments are then linked to appropriate vectors and cloned in a suitable host cell population.
A cDNA library (complementary DNA) contains DNA prepared from the mRNA present in a given cell population using the enzymes reverse transcriptase, which produces single-stranded DNA from mRNA, and DNA polymerase, which converts single-stranded DNA into double-stranded DNA. The resulting cDNA represents the genes expressed in the cell population as a subset of the entire genome, and can be cloned using a vector and suitable host cell. The cDNA will not include introns or regulatory sequences as these are removed from the RNA during processing. A cDNA library can also be prepared using reverse transcriptase PCR (RT-PCR).
The identification and analysis of genes and gene products
Restriction enzymes (to cut the DNA) and gel electrophoresis (to separate the resulting fragments) can be used to produce a physical map of DNA segments in a process known as restriction mapping.
There are also a number of techniques that can be used to identify specific genes or gene products within a gene library: Southern blotting detects the presence of particular nucleotide sequences in a collection of DNA fragments using a DNA probe - a section of DNA labelled using radioactivity or chemical fluorescence; Northern blotting investigates gene transcription by identifying specific RNA sequences using labelled DNA probes; and Western blotting detects specific proteins using labelled antibodies.
However, the most powerful experimental technique for investigating genetics at the molecular level is DNA sequencing, which allows the nucleotide sequences of genes - even whole chromosomes - to be determined. Similar techniques are available for analysing the nucleotide sequences of RNA molecules and the amino acid sequences of proteins. Automated sequencing technologies are now allowing us to sequence the entire genomes of organisms from bacteria to human beings.
Molecular genetics and biotechnology
The new techniques of molecular genetics, combined with developments in associated biotechnologies, have led to advances in a number of different fields. We can now analyse the genomes of species that make an important contribution to agriculture, fuel production or drug development. We can move specific genes from one organism to another to create transgenic plants and animals, and use animal cloning techniques to produce animals that are genetically identical.
The technique of genetic fingerprinting has found many applications, including the identification of individuals and the relationships between individuals. Research intogene therapy examines the possibility of introducing cloned genes to compensate for defective, mutant genes. In other areas - for example, human cloning and stem cell research - there are ethical issues that must be addressed alongside the scientific developments.
Q.6 Agricultural research has significantly enhanced the productivity of all field crops in Pakistan except the oilseeds. Narrate the main shortfalls and discuss the role of various institutions/agencies working on these lines.

INTRODUCTION
There is less established cropping system for oilseed crops in the country. The major crops in the existing system are wheat, cotton, rice and maize. However, some pockets for sunflower such as rice-sunflower-rice and cotton-sunflower-cotton are emerging in all the provinces. Currently, 748 thousand ha of the total cropped area is under oilseed crops.
Pakistan has been constantly and chronically deficient in edible oil production. At present, about 70% of the domestic requirements are met through imports. Since early 1970s its import increased at the rate of 12.5% annually and the trend will further not only continue but will also get worsen with increase in population. However, efforts have been made to increase its local production. The area under oilseed crops during 1990-91 was 473,000 ha with the production of 3650,000 tones, which was 748,000 ha producing 4767,000 tones in 2008-09. Sunflower and Canola with high oil yield per unit area have emerged major oilseed crops and have the potential to narrow the gap between production and consumption of edible oil.
Yield Potential
Big gaps exist between potential yield and national average yield of various oilseed crops. About 78% of the yield potential has not yet been achieved in rapeseed-mustard, 77% in groundnut, 69% in sunflower, 62% in sesame, 73% in linseed and 70% safflower (Table 4). However, the progressive farmers are already achieving more than 70% of the yield potential indicating that there is a large scope for vertical increase in oilseed production through the use of proper crop management practices.
FACILITIES
Oilseeds Research Program has following facilities at NARC:
• Twenty hectare land for various field trials.
• Oil quality laboratory for evaluation of various quality parameters.
• Storage facility for inputs and crop harvests.
• NUYT and adaptability trials on hybrids are also conducted at different federal and provincial research institutes of public and private sectors.
SERVICES
Oilseeds Research Program extends following services to public as well as private organizations:
Research
• Acquisition and distribution of oilseed germplasm to various collaborators.
• Evaluation of candidate varieties and oilseed hybrids for adaptability, resistance to insect pests and diseases and oil quality.
• Conducting and maintenance of kharif and rabi trials at NARC.
Extension
Extends advisory services to farming community on oilseed production/protection issues from time to time. In addition, farmers’ are also given awareness about the improved production technology of oilseed crops in field days and through print and electronic (Sohni Dharti) media.

Education
• Scientists of Oilseed Program also extend advisory/research services (as supervisor) to various M.Sc, PhD and Internee students from different universities.
• Trainings are also imparted to in-service extension staff and oilseed growers.
• Dr. M. Yasin Mirza, PSO, has scrutinized about 100 synopsis of M.Sc./Ph.D. students as nominated external member, synopsis committee of Plant Breeding and Genetics department, PMAS Arid Agriculture University, Rawalpindi.
• In-service qualification improvement/training for higher studies
CURRENT RESEARCH
Objectives
• Acquisition, maintenance and evaluation of germplasm of oilseed crops
• Development of parent lines of sunflower and canola for hybrid development
• Development of high yielding, early maturing, insect and disease resistant oilseed varieties/hybrids
• Development/dissemination of improved production technology on oilseed crops
• Collaboration with Public and Private Sector for promotion of oilseed crops
• Demonstration of local hybrid seed production of canola and sunflower for private sector
On-going activities
a) Coordination
• Maintaining genetic diversity through acquisition and distribution of relevant germplasm.
• National Uniform Yield Trials (varieties and hybrids) in sunflower, rapeseed, mustard, sesame and groundnut.
• Annual oilseed review and planning meeting.
• Traveling seminar.
b) Research
• Utilization of oilseeds germplasm for genetic enrichment and variety development
• Testing of promising entries/lines in preliminary and advanced yield trials
• Conducting agronomic studies on oilseed crops
• Screening of oilseed crops for various insects/pests
• Development of local sunflower hybrids
• Development of canola type varieties and hybrids of rapeseed
• Development of canola type mustard varieties
• Development of phyllody and shattering resistant varieties of sesame
• Development of high yielding, medium and short duration groundnut varieties
• Seed production of pre-basic seed of sunflower and canola hybrids
• Improving production technology in oilseed crops
Q.7 Write short notes on any of four foolowing
a) challenges in livestock management
Livestock is a major sector in agriculture. Livestock accounts for 52.2 % of agricultural value added. It contributes 11%to Gross Domestic Products (GDP). About 30-35 million rural people depends directly or indirectly on livestock sector for their livelihoods. It has potential to absorb more rural workforce to alleviate rural poverty if proper attention is given to this sector. Pakistan is proud to be world’s fifth largest milk producer. In addition to food products, livestock sector also provide draught power, milk, meat, eggs, manure which is used as fuel or fertilizer, feathers, fiber, hides, and horns. In today’s world, it role in food security can not be overstated. In order to achieve sustained development in agriculture, it is extremely important for the government to give more attention to livestock and dairy sector. Realizing its significance to poverty alleviation, the government has started giving some attention to this sector but no big national or international investment have been seen in dairy, beef, mutton or carpet wool production sub- sectors of livestock. Most of the livestock production system is still orthodox and rural subsistence oriented. Some investment in this sector is appreciable but still there is a lot which need to be done
It is pre-request for the sustainable economy of the country to increase the animal production. There are many issues in the animal production which should be addressed properly. Constraints and problems to increase livestock or animal production are almost similar in Asian countries. The most considerable constraints in Pakistan are nutrition, animal health, animal productivity/genetic make-up of the animals, provision of finance to livestock farmers, livestock extension and marketing. These factors are briefly discussed below.
Nutrition
Adequate nutrition is a major problem in livestock production. With out providing the required nutrition to the animal the genetic potential can not be exploited. It is yet to be decided that how much nutrients our animals needs to express their full genetic potential of productivity. To develop feeding standards of buffaloes, cattle, sheep and goat, no serious effort has been made. It is difficult for extensionist to recommend accurately to livestock farmers that what standard he has to follow to feed his cow for cost-effective milk and meat productivity. Some advancement has been made in this regard however there is a lot need to done for revolution in animal nutrition. The availability of green fodder is not sufficient. Fodder availability can be ensured round the year by following the “year around fodder availability chart” to cultivate fodder. Cotton cake (Khal) was considered a balance diet by the farmers but in fact it is unbalanced diet which leads to less productivity.
Wheat and rice straw (toorhi) is commonly used by the farmers for their animals with out urea treatment. Urea treatment is strongly recommended because by this practice the nutritional value of straw can be increased up to 70 percent. it was commonly observed that farmers do not know that how to treat the straw. There is need to educate the farmers in this regard.
Preservation of fodder can play an important role in nutrition. Silage and Hey making are common techniques to preserve fodder. The preserved fodder has more nutritional value and can be used by animals in the seasonal starvation. But farmers do not practice the silage and hey making which exacerbate the nutritional deficiency.
Wanda is considered a complete diet for the animals by the village people and they use to feed it to the pregnant and lactation animals. It is not a good practice because wanda is not a balanced diet and animal need nutrients in addition to this. As farmers do not have awareness about the fact, their ignorance leads under nutrition of animals.
Health
Livestock health is a limiting factor to productivity. A major problem is the lack of knowledge and awareness about the productive benefits of disease control. Those farmers, who are aware of the benefits, have limited access to appropriate vaccines and therapeutic drugs. Animal production systems are affected by different types of diseases with varying capacity. The disease i.e. helminthosis and tick-borne are more important regarding animal productivity. In short the diseases can seriously affect productivity and profitability.
Vaccination and treatment for the animals was generally ignored by the livestock farmers which results huge losses regarding productivity and number of heads.
Farmers use to inject oxytocine to lactating animals for milk let down which entirely hazardous for reproductive organs and productivity as well.
Farmers use to practice traditional methods for animal cure which exacerbate the problems for animal health.
Lack of diagnosis of diseases is major factor in low productivity. Due to insufficient diagnostic laboratories the doctors use hit and trial methods for diagnose and cure which results inefficiency in the treatment.
Mastitis (inflammation of udder) is a major problem in lactating animal. It significantly decreases the milk production. Farmers have no awareness about the diagnosis and cure about this disease. Farmers usually care their diseased animals up to 2-3 days but this disease needs care up to 10 days.
External and internal parasites of animals also cause low productivity. It is important to check the fecal sample in every month to diagnose and de worm the animals. But the practice is ignored by the farmers.
In Pakistan, quacks (neem hakeem) are very active in curing animals in the villages. These non-technical persons often treat animals with hit and trial methods which some time cause even death of the animal.
Animal Productivity/Genetic Potential
Pakistan has breeds with low genetic potential Sire (bull). The breeds with best potential such as Sahiwal cow and Nili-Ravi buffalo are rarely found at the farms of small and medium farmers who contribute the big share of heads. These pure breeds are in fact in danger. There is need to save and exploit the genetic potential of the high yielding breeds. It is common observation that there is a trend among farmers to cross the animals by imported semen. This practice is a big threat to our local and potential breeds. It is interesting to tell that Australia had demanded the 100 pure Sahiwal breed and Pakistan could not provide. It shows that the country is being lost the breed.
Lack of Livestock Credit
To establish the modern livestock farms, it needs huge investment. Unlike crop sector, livestock sector required more capital. The absence of credit disbursement to small and medium-scale farmers the involvement of poor in the commercialization of livestock production is restricted.
Poor livestock extension activities
Livestock extension wing in the country is poorly performing and biased toward large farmers tending to neglect poor rural livestock-keepers. Public sector Follow a top-down transfer of technology approach. It is now universally accepted that this approach is not result oriented instead bottom up approach should be adopted in which the participation of the livestock farmers should be ensured. In extension programs only large ruminants are focused and the other species are almost excluded which need to be addressed.
The extension services are concentrated in the areas where potential for livestock is high. The services should be evenly provided to the farmers, and neglected areas in fact deserve more. The extension messages are not frequently disseminated through print and electronic media. There is dire need to educate the farmers as with out educating there the dream of high productivity can not be realized.
Poor Marketing System
Proper marketing system encourages the animal productivity. Poor marketing system is also a significant constraint in the animal productivity. Private sector has organized the farmers’ association for their own interest. These associations collect milk for the organizations. Regarding marketing farmers are on the mercy of beoparies and dodhies. These market players exploit the poor farmers. There should be systematic marketing system which could ensure the profit share of the farmers.
b) genetic resources and their conservation
For the conservation of the genetic resources two options are available: a) outside of their natural habitat (ex situ) in a gene or germplasm bank or b) in their natural habitat (in situ) with appointed farmers or scientists, which act as guardians/custodians of the resource.
Gene Banks Once a genetic resource is registered it should be conserved in a gene or germplasm bank. The most important responsibility of a gene bank is to treat a new sample in a way that will prolong its viability while ensuring its genetic integrity. The samples are monitored to ensure that they are not losing viability. A cornerstone of gene bank operations is the reproduction—called regeneration—of its plant material. Plant samples must periodically be grown out, regenerated, and new seed harvested because, even under the best of conservation conditions, samples will die after a lifespan of up to 20 years. Moreover, they are intended to ensure that the conserved resources are used in farmers’ fields, breeding programmes or in research institutions. Finally, gene banks must be able to deliver healthy samples to the farmers, breeders and researchers. The management of the bank can be carried out by the agency or an independent institute, e.g. a university. For example, the Tamil Nadu Agricultural University in the southern province of Tamil Nadu in India has established a gene bank within its premises in Coimbatore City. The bank, set up at a cost of Rs 12 million, has been funded by the Indian Council of Agricultural Research to conserve genetic resources for future use. The bank intends to store 22,000 varieties of rice, pulses, and grains which can be used by farmers and breeders. The estimated storage life of seeds is likely to be 5 to 20 years depending upon the nature of the seed.
In situ Conservation The second option is to conserve genes in the areas of origin or in areas where the resources are traditionally grown (in situ). On farm conservation is entrusted to custodian or steward farmers or scientists who maintain and multiply the local varieties which have been entrusted to them. A custodian farmer may be appointed by the managing agency. The selection of custodians can be based on his engagement in the conservation of regional resources, specific experience and proven professional skills. The custodian should be obliged to share his knowledge and the genetic resources with other farmers and for scientific purposes. In return the custodian should be reimbursed or compensated for his services. Further mutual duties and rights shall be determined in a contractual agreement between the custodian and the agency. An example for a secondary regulation from Tuscany (Italy) relating to ex situ and in situ conservation institutions can be downloaded here.
c) organic crop production
Organic Crop Production Basics
Organic crop production is a system of farming based on ecological principles. One formal definition states that, "Organic farming seeks to create ecosystems that achieve sustainable productivity and provide control of pests through a diverse mix of mutually-dependent life forms, through recycling of plant and animal residues, and through crop selection, crop rotation, water management and cultivation. Soil fertility is maintained and enhanced by a system which optimizes soil biological activity as the means to providing nutrients for plant and animal life as well as to conserve soil resources".
A crop cannot be marketed as "Certified Organic" in Manitoba until the land on which it is grown has been free of synthetic fertilizers and pesticides for at least three years prior to crop harvest. The third harvest on the land can therefore be recognized as an organic product.
The primary challenges in an organic crop production system include:
1. Fertility
2. Weed Management
3. Insect Management
4. Disease Management
5. Soil Conservation

Fertility
Soil testing on a regular basis is an important tool in the management of an organic cropping system. As well as providing the grower with an approximate level of nutrients in the soil, the soil test can help measure the benefit of various agronomic practices over a number of years.
There are several products and practices that will supply nutrients organically:
• application of composted animal manure
• green manure plow-downs
• including legumes in the crop rotation
• alternating high and low-nutrient demand crops
• alternating deep and shallow-rooted crops
• summerfallow
• use of certain fertilizers (from the list of permitted inputs)
• use of certain microbial inoculants (from the list of permitted inputs)

Weed Management
Effective weed management depends on a thorough understanding of the biology and growth habit of the species in question. In most cases, a combination of a number of cultural and preventative practices will be required to effectively deal with weeds:
• field and crop sanitation
• crop rotations
• crop competition (which includes the variables of crop selection, seeding date, seeding rate, row spacing, seeding depth and plant nutrition)
• both out-of-crop and in-crop tillage
• use of plants with beneficial allelopathic effects
• mowing and burning
• biological controls

Insect Management
As with weed management, successful insect control will depend on incorporating a number of control strategies together:
• diverse crop rotations
• field and crop sanitation
• weed management
• seeding date and seeding rate
• management of summerfallow and stubble
• seeding trap strips
• balanced soil nutrition
• resistant cultivars
• biological controls
• insect hormones
Disease Management Plant disease control measures are aimed at reducing or eliminating one of the three factors involved in disease development: an infectious pathogen, a susceptible host and a suitable environment. Not only do these factors interact, but disease control strategies also must be woven together with management methods to address weed, insect and other production concerns.
Considerations in disease management should include:
• rotation of susceptible and resistant crops
• the use of resistant cultivars
• field sanitation: managing disease-infected straw, stubble, chaff and volunteer plants
• seed sanitation: importance of uncracked and disease-free seed
• planting dates, rates and depth
• maintaining balanced soil nutrient levels, including both macronutrients and micronutrients
• the use of livestock manure to stimulate higher populations of soil microorganism incorporation of green manure cover crops

Soil Conservation
As in other farming systems, the challenge in the organic system is to employ soil conservation practices that are best adapted to each particular farm. Such practices that use herbicides are not an option, although attempts are made to not use tillage any more often than in conventional systems. Therefore, the organic crop producer may need to use a combination of effective soil conservation measures. These may include:
• optimizing the use of crop residues to replenish soil organic matter and improve soil properties such as water infiltration, water storage, and particle aggregation.
• limiting tillage depth, speed and the number of operations to conserve crop residue and soil moisture.
• appropriate stubble height
• direct seeding
• extending crop rotations to reduce summerfallow
• using wind barriers such as annual crops, perennial grasses and shelterbelts in crop or summerfallow situations.
• strip cropping at an angle perpendicular to the prevailing wind direction
• cover crops to protect the soil from wind and water erosion during certain vulnerable periods
• incorporating green manure to improve soil quality
• effective use of animal manure
d) potential of horticulture sector as an industry
Horticulture produce holds a huge market for exports. The relative importance of this sector can be gauged with high growth rate of exports of fruits and vegetables from Pakistan due to ever increasing demand in the existing and new international markets. Some of the fruits grown have great potential for exports, which are available in volumes, varieties and are of rich flavor. These are mangoes, citrus (Kinnow), grapes, dates, apples, peaches and cherries. Other prominent fruits that have enormous export potential are plums, pears, guava and loquat. Among vegetables, potatoes and onions are vastly grown in Pakistan, hold a large global market because of competitive advantage due to superior variety, volume and price.
Horticulture related processing industry is another mentionable area, which has tremendous export potential. The demand of processed food is high in the export markets such as graded fresh fruit, citrus juice, mango pulp, tomato paste, etc.
e) range management in Pakistan
Range Management Rangelands of Pakistan are fragile ecological resource and provide feed and shelter to animals and fruit, wood, sports hunting and eco-tourism to the human being besides conserving environment provided they are properly managed. Sustainable grazing management and rangeland resource use is a key issue of concern in most rangeland regions of Pakistan, therefore, rangeland research at PARC focuses on assessing the sustainable use of these drought prone rangelands.
NARC
• Baseline survey of vegetation cover and composition of Pabbi Hills showed a 34% ground cover. Bermuda grass (Cynodon dactylon) dominated with 11.5% cover, followed by Mesquite (Prosopis juliflora) with 10% cover.
• Dry matter production 3.81 t.ha and higher sprouting rate i.e. (81%) was recorded for blue panic (Panicum antidotale) followed by finger grass (Digitaria swazilandensis) in semi arid conditionsof Pabbi Range.
• A combination of 35% green panic (Panicum m a x i m u m ) a n d 6 5 % cowpeas (Vigna unguiculata) gave highest forage yield. Combination of green pani c and inoculated cowpea produced 13% more forage as compared to combination of green panic and uninoculated cowpeas
• At 100 cm clipping height 35% higher biomass was produced over 10 cm height in double hedgerows of Ipil ipil. Significant increase in wheat yield was observed in alleys of under hedgerows spacing (15 cm) as compared to narrow spacing (5 m).
AZRC, Quetta
• Mulberry and Russian Olive plantations were carried out on micro-catchment water harvesting structures at AZRC range area for efficient utilization of rain water and production of forage for livestock.
• As a result of better rainfall distribution during the winter and spring months many new range species were observed.Fodder shrub plantation (Atriplex canescens, A.lentiformis and Salsolavermiculata) on microcatchment water harvesting structures was established w i t h c o m m u n i t y participation at Siddiqabad (Mastung). Shrub survival percentage was 70-80%.Native range vegetation was also improved by protecting the community range area from grazing. During winter and spring months, about 2000 seedlings of different native and exotic species were planted at the site on natural runoff places.Community Fodder shrubs nursery was also established for demonstration and distribution of seedlings to the farmers interested in plantation on range areas.
• Harvesting of Glycyrrhiza glabrea (Malathi) was completed. The harvesting was done after three years of plantation and 80 kg fresh weight of roots was obtained 2 from an area of 9 m .Seeds and seedlings of different exotic medicinal herbs were provided to Women University, Quetta f o r e st a b l is hme n t o f medicinal herb garden for research purpose.
AZRI, Umerkot
• Of 16 desert flora such as trees, shrubs and grasses species collected from live herbarium, highest seed yield of 3.0 kg/plant was obtained from Acacia ampliceps(Australian Babur) .
f) foot and mouth disease

Foot and Mouth Disease (FMD) is a highly infectious viral disease of cloven hoofed animals. FMD is not transmissible to humans but the disease has major economic consequences.
In the past Foot and Mouth Disease outbreaks in non-endemic countries have been controlled through the mass culling of infected and in contact animals. New legislation and the development of marker vaccines and test kits allows for the use of vaccination as part of a FMD control strategy.
Q.8 Differentiate between the following (Any Four)

a) Gram blight and gram wilt
• Gram Blight
Blight Caused by Mycosphaerella rabiei (Ascochyta rabiei)
Symptoms: The disease starts from the base of the plant, which result in the death of the whole plant. The infected plants could not be differentiated in early stages from the distance. The affected plants may show partial or total drying, with purple to dark brown spots of different sizes on stems, branches, leafstalks and leaflets. These spots become brown to black lesions and affected plants or plant parts show burnt appearance. Primarily individual infected plants may be observed scattered but later on the disease appear in circular patches and ultimately the entire field come under attack, therefore, whole crop may be destroyed completely. The disease symptoms may also occur on the pods and seeds. The pods produce blackish spots while the seeds become shriveled.
Perpetuation: The disease causing fungus is a soil borne and can remain viable for considerable periods. Seed may also help fungus to survive.
Control: Cultivation of disease resistant variety is only the most easy, economical and safe method. However, following measures could be beneficial if applied
• Gram Wilt
Wilt (Caused by Fusarium oxysporum f. sp ciceri)
Symptoms: The plants start wilting and ultimately dry up at seedling and/or at flowering stage. The diseased plants are pulled out easily, due to the loss of rigidity. Sometimes, sudden drooping of leaves and/or only a few branches of a single plant are affected. The disease mostly spreads in patches, but entire field may also be affected in severe conditions. Severe damage has been reported during early pod filling.
Perpetuation: The disease causing fungus may survive and carried over from year to year by sowing infected seed, while the diseased plant debris lying in the field or in the threshing area also helps the fungus to remain alive.
Control: Cultivation of disease resistant variety is only the most easy, economical and safe method. However, following measures could be beneficial if applied.
b) C3 and c4 plants
By looking at their anatomy, in C3 plants, bundle sheath cells do not contain chloroplasts; carbon fixation and Calvin Cycle reactions occur in mesophyll cells (and in the presence of oxygen). In C4 plants, the bundle sheath cells contain chloroplasts; carbon is fixed in mesophyll cells, then transported to bundle sheath cells where Calvin Cycle reactions occur in the absence of oxygen. In both, photosynthesized sugars then enter the plant's vascular system.
C4 have a concentric arrangement of the bundle sheath and mesophyll layer, the bundle sheath is also thicker. Another difference is their intervenial distances, from one bundle sheath to another you have in C4 only around 4 mesophyll cells but on 3 they are separated by 12.
Overall, C4 plants are more adapted to environments with more oxygen, and C3 plants are more adapted to environments with more carbon dioxide.
Examples:
C3----->wheat, barley, potatoes and sugar beet. (most of the plants are C3)
C4----->fourwing saltbush, corn ,many of summer annual plants.
c) Biological nitrogen fixation and nitrification.
Nitrification is the biological oxidation of ammonia with oxygen into nitrite followed by the oxidation of these nitrites into nitrates - carried out in soil by the action of nitrifying bacteria on decaying organic matter.

Nitrogen fixation is the conversion of atmospheric nitrogen into compounds, such as ammonia, by natural agencies or various industrial processes - eg. Rhizobium bacteria in the root nodules of legumes fix atmospheric nitrogen.
d) Silviculture and sericulture
Silviculture is the practice of controlling the establishment, growth, composition, health, and quality of forests to meet diverse needs and values. The name comes from the Latin silvi- (forest) + culture (as in growing). The study of forests and woods is termed silvology.
Sericulture, or silk farming, is the rearing of silkworms for the production of raw silk. Although there are several commercial species of silkworms, Bombyx mori is the most widely used and intensively studied.
e) Respiration and transpiration
Respiration – the process of metabolizing (burning) sugars to yield energy for growth, reproduction and other life processes
Transpiration – the loss of water vapor through the stomata of leaves.
f) Basic seed and certified seed.
Breeder seed is produced from nucleus seed it is 100% genetically pure it have all the morphological charecters that the breeder incorporated the breeder seed will have a golden yellow label.

Certified seed produced from foundation seed by govt agencyor pvt agency its qualities are certified by seed certifying agency it is given a blue label and supplied to farmers for cultivation.

Answers Of part I are as under :-
1) a
2) d
3) e
4) d
5) e
6) d
7) d
8) a
9) a
10) b
11) c
12) d
13) c
14) d
15) a
16) a
17) b
18) c
19) d
20) c