Your Answer : (Not Answered)

Correct Answer : C

The law of homologous series was given by N. I. Vavilov.

The Russian botanist Nikolai Ivanovich Vavilov stated the law of homologous series in variation in 1920. It says that related species and genera show similar series of heritable variation, so a variant found in one species (for example, a grain colour or awnless form in wheat) can be expected in related species such as barley or rye. He is also known for the centres of origin of cultivated plants.

Darwin gave the theory of natural selection, Mendel the laws of inheritance, and M. S. Swaminathan led the Green Revolution in India; none of them proposed this law.

Your Answer : (Not Answered)

Correct Answer : C

Koelreuter carried out his experiments in Tobacco.

The German botanist Joseph Gottlieb Koelreuter made systematic crosses between species of tobacco (Nicotiana) in the 1760s. He produced the first scientifically recorded plant hybrids, observed that the hybrids were often more vigorous than the parents (an early description of heterosis), and showed that both parents contribute to the offspring.

Pea was Mendel's plant, a century later, and maize is associated with the work of Shull and East on hybrid vigour. Carnation was not Koelreuter's material.

Your Answer : (Not Answered)

Correct Answer : B

The method is Speed breeding.

Speed breeding grows plants in controlled growth chambers or glasshouses under extended photoperiods of about 22 hours of light a day, with controlled temperature, so that long-day crops such as wheat, barley and chickpea flower and set seed much faster. Up to four to six generations a year can be raised instead of one or two, which shortens the time to develop a variety.

Shuttle breeding, made famous by Norman Borlaug, gains two generations a year by moving material between two field locations with different seasons, not by controlled light. Landrace enrichment and natural selection in farmers' fields do not shorten generation time at all.

Your Answer : (Not Answered)

Correct Answer : A

The preferred trait is erectophile leaves and compact architecture.

Erect leaves let light penetrate deeper into a dense canopy, so the lower leaves also photosynthesise instead of being shaded out. A compact plant also takes up less space and competes less with its neighbours, which is why modern high-yielding rice, wheat and maize ideotypes, such as those described by Donald, have short stature and upright leaves.

Planophile (horizontal) leaves, a sprawling habit, large drooping leaves and bushy, broad-leaved forms all capture light in the top layer and shade the rest of the canopy, which suits a sparse stand but not a dense planting.

Your Answer : (Not Answered)

Correct Answer : C

The method useful for purifying existing varieties is Mass selection.

In mass selection, a large number of plants true to the variety's type are chosen from the population and their seed is bulked to raise the next generation, while off-types are discarded. It is simple and quick, and it is the standard method for purifying varieties that have become mixed or degenerated, and for maintaining them.

The pedigree and bulk methods are used to develop new varieties from segregating generations after a cross, and the backcross method transfers a particular gene, such as disease resistance, into an established variety.

Your Answer : (Not Answered)

Correct Answer : C

The F2 has 81 different genotypes.

Each heterozygous locus (Aa) segregates into three genotypes in the F2: AA, Aa and aa. Loci assort independently, so the counts multiply:

\[ \begin{aligned} \text{genotypes} &= 3^{n} \\ &= 3^{4} = 81 \end{aligned} \]

The distractors come from the other standard formulas: \(2^{4} = 16\) is the number of gamete types and of phenotypes with complete dominance, \(4^{4}\) gives the number of gamete combinations, and \(3^{3} = 27\) would apply to only three loci. 64 is \(4^{3}\), which fits none of these.

Your Answer : (Not Answered)

Correct Answer : B

The monohybrid test cross ratio is 1:1.

A test cross crosses an individual of dominant phenotype with the homozygous recessive. For a monohybrid heterozygote, Aa crossed with aa gives half Aa (dominant phenotype) and half aa (recessive phenotype), a 1:1 ratio, which shows the tested parent was heterozygous.

3:1 is the monohybrid F2 ratio, 9:7 a dihybrid F2 ratio modified by complementary gene action, and 1:7 is not a standard ratio. The dihybrid test cross ratio is 1:1:1:1.

Your Answer : (Not Answered)

Correct Answer : D

Golden Rice is rich in Beta Carotene.

Golden Rice was developed by Ingo Potrykus and Peter Beyer by inserting genes for the beta-carotene pathway (phytoene synthase from daffodil, later maize, and a bacterial carotene desaturase) into rice, so that the endosperm makes beta-carotene, the precursor of vitamin A. The yellow-gold colour of the grain gives it its name. It was developed to fight vitamin A deficiency in rice-eating populations.

It is not enriched in lysine (the aim of quality protein maize), vitamin C or iron.

Your Answer : (Not Answered)

Correct Answer : D

The answer is Reduced stability, as the Commission's key has it.

Nanoparticles are defined by a size of about 1 to 100 nm, and their useful properties follow from it: a very high surface area to volume ratio and, because so many atoms sit on the surface, increased reactivity. The first three options are the standard defining features, so each is correct.

The fourth is the odd one out in this list of properties. A caution: bare nanoparticles do tend to clump together, which is why stabilisers are used, so a few texts do mention lower stability. The question follows the usual list, in which only the first three appear, and keys the fourth as not correct.

Your Answer : (Not Answered)

Correct Answer : C

Somatic hybridisation is achieved through Protoplast fusion.

In somatic hybridisation, the cell walls of somatic (body) cells from two plants are removed with enzymes to give naked protoplasts, which are then fused using polyethylene glycol or an electric pulse. The fused cell is cultured to regenerate a hybrid plant, which can combine species that cannot be crossed sexually; the pomato is a well-known example.

Grafting joins tissues but does not merge genomes, conjugation is the transfer of DNA between bacteria, and recombinant DNA technology transfers selected genes rather than fusing whole cells.

Your Answer : (Not Answered)

Correct Answer : C

The Seeds Act was enacted in 1966.

The Seeds Act, 1966 provides for regulating the quality of seeds sold for sowing. It set up the Central Seed Committee and the system of seed certification and seed testing laboratories, and it requires that notified kinds of seed meet minimum standards of germination and purity. The Seeds Rules followed in 1968.

1955 is the year of the Essential Commodities Act, under which the Seeds (Control) Order of 1983 was later issued. 1971 and 1988 are not years of the Seeds Act; 1988 is the year of the New Policy on Seed Development.

Your Answer : (Not Answered)

Correct Answer : B

ISTA stands for International Seed Testing Association.

ISTA was founded in 1924 and is based in Switzerland. It develops and publishes the International Rules for Seed Testing, which standardise methods for purity, germination, moisture and other tests, and it accredits seed testing laboratories so that their certificates are accepted in international seed trade.

'International Seed Technology Association' and 'Indian Seed Testing Association' are not this body, and the international trade association in seeds is the International Seed Federation, not ISTA.

Your Answer : (Not Answered)

Correct Answer : C

Cytoplasmic male sterility was first discovered in Maize.

M. M. Rhoades reported the first case of cytoplasmically inherited male sterility in maize in 1931 and 1933. The Texas (T) cytoplasm of maize was later used on a large scale for hybrid seed production in the United States, until its susceptibility to southern corn leaf blight caused the epidemic of 1970.

CMS in wheat (from Triticum timopheevi cytoplasm), in rice (the wild abortive cytoplasm used in Chinese hybrid rice) and in cotton were found later.

Your Answer : (Not Answered)

Correct Answer : C

The system most widely used is CGMS, cytoplasmic genetic male sterility.

In CGMS, sterility comes from the cytoplasm, but nuclear restorer genes can restore fertility. That makes the three-line system possible: an A line (sterile), a B line (maintainer) and an R line (restorer), giving fertile F1 hybrids that set seed. It is the basis of hybrid seed production in rice, sorghum, pearl millet, sunflower and other grain crops.

Plain CMS without restorers gives sterile hybrids, so it is useful only where seed set does not matter, such as onion or ornamentals. GMS lines cannot be maintained as a pure sterile stock, and TGMS needs precise temperature conditions, so neither is as widely used.

Your Answer : (Not Answered)

Correct Answer : B

When the two alleles of a gene in an individual are different, they are called heterozygous alleles. An individual with Aa is heterozygous for the gene.

Homozygous alleles are identical, and homoduplex and heteroduplex are terms for DNA molecules, not for alleles.

In a heterozygote the two alleles of a gene are different, as in Tt, so the two forms of the gene differ. In a homozygote they are the same, as in TT or tt.

Your Answer : (Not Answered)

Correct Answer : D

Steckling is the term for the root of radish used in the root-to-seed method of seed production. The roots are pulled and replanted.

Cucumber, garlic and onion seed production does not use stecklings.

In the root-to-seed method the roots of radish are pulled when mature, trimmed and replanted to flower and set seed, so that the true root type can be selected. The replanted root is the steckling.

Your Answer : (Not Answered)

Correct Answer : C

The biolistic method, also called the particle gun or gene gun, shoots 1-2 micrometre tungsten or gold particles coated with DNA into cells.

Electroporation uses electric pulses, microinjection uses a fine needle, and lipofection uses lipid vesicles, so they do not use coated metal particles.

Biolistics, or the gene gun, was developed to transform plant cells with thick walls, which resist other methods. The particles of gold or tungsten carry the DNA through the wall and into the cell.

Your Answer : (Not Answered)

Correct Answer : C

The Mal d 3 allele of apple is related to allergenicity. Mal d 3 is one of the apple allergens, a lipid transfer protein that can cause allergic reactions in some people.

It does not code for self-incompatibility, drought tolerance or resistance to late blight.

Allergy to apple in Europe is mostly caused by the protein Mal d 1, and Mal d 3 is a lipid transfer protein that causes allergy in southern Europe. Breeders study these genes to select apples that are less allergenic.

Your Answer : (Not Answered)

Correct Answer : C

The dihydroflavonol-4-reductase (dfr) gene was used to modify flower colour in petunia. The gene codes for an enzyme in the anthocyanin pigment pathway, and introducing a dfr gene from maize into a petunia mutant gave brick-red flowers, a colour not available in the species.

Fragrance, flower architecture and plant size are controlled by other genes, not by dfr.

Dihydroflavonol-4-reductase is an enzyme in the pathway that leads to anthocyanin pigments. Petunia lacks the enzyme in the form needed to make pelargonidin-based pigments, so adding a dfr gene from another species changed the flower colour to brick red.

Your Answer : (Not Answered)

Correct Answer : A

Sporophytic self-incompatibility occurs in cauliflower, a Brassica. In this system the pollen's behaviour is decided by the genotype of the plant that produced it, not by the genotype of the pollen grain, and it is used to produce hybrid seed in the cabbage family.

Cowpea, okra and onion do not rely on this system.

In sporophytic self-incompatibility the pollen's reaction is decided by the genes of the plant that made it. This system is found in the Brassicaceae, so cauliflower, cabbage and broccoli have it, and growers use it to produce F1 hybrid seed by crossing self-incompatible lines.