Botany 2006 (Civil Services)

 Raunkiaer gave the description of life-forms in plant communities.

Shotgun technique is employed in insertion of genomic clones into a vector. 

Plants developed through suspension cultures generally exhibit genetic variations.

 The correct answer is option no.3.

 Callose is a plant polysaccharide. It is composed of glucose residues.

Phragmoplasts are temporary structures formed during telophase of cell division in plant cells. They consist of microtubules and actin filaments that guide vesicles containing cell wall materials to the forming cell plate. This matches option B, which correctly describes them as guiding dictyosome vesicles to the site of cell wall formation. Options A, C, and D describe different cellular structures.

The synaptonemal complex is a protein structure that forms between homologous chromosomes during the zygotene stage of prophase I in meiosis. It facilitates synapsis (pairing) of homologous chromosomes and crossing over. This matches option D. The other options refer to different cellular structures: histone complexes (DNA packaging), lysosomal complexes (digestion), and liposomal complexes (lipid transport).

Dalbergia sissoo (Indian rosewood) can be propagated vegetatively through stem cuttings, root cuttings, and root suckers. Among the options, intact roots (option C) are correct because they produce root suckers that develop into new plants. Root cuttings are a common propagation method for this species. Options A, B, and D are incorrect - flower buds cannot vegetatively propagate, stem cuttings are not the primary method listed, and leaf margins are not used for Dalbergia propagation.

Statement 1 is incorrect because beta-oxidation occurs in mitochondria (not glyoxysomes) in animals, and in glyoxysomes in plants, not 'only' in glyoxysomes. Statement 2 is also incorrect because beta-oxidation produces BOTH NADH and FADH2, not just NADH. Each cycle produces one NADH, one FADH2, and one acetyl-CoA. Therefore BOTH statements are wrong, making option D correct.

Biosensors are indeed used in all three applications: (1) In vitro diagnostics like glucose monitoring for diabetes, pregnancy tests, and infectious disease detection; (2) Detection of microbial contaminants in food products through immunosensors or DNA-based sensors; (3) Environmental monitoring of pollutants like heavy metals, pesticides, and other contaminants in air, water, and soil. Therefore all statements are correct, making option D the right answer.

 Electroporation, or electropermeabilization, is a microbiology technique in which an electrical field is applied to cells in order to increase the permeability of the cell membrane, allowing chemicals, drugs or DNA to be introduced into the cell.

Southern hybridization is a technique where DNA is transferred from a gel to a membrane and probed with complementary DNA sequences, making it DNA-DNA hybridization. The technique is named after Edwin Southern, while Northern (RNA-RNA) and Western (protein-protein) are other related techniques.

pBR-322 was one of the first widely used cloning vectors and was derived from E. coli plasmid Col E1. It contains antibiotic resistance genes (ampicillin and tetracycline) and multiple cloning sites, making it ideal for recombinant DNA work.

Terpenes are composed of isoprene units (C5H8), which are five-carbon compounds that serve as building blocks. Monoterpenes have 2 isoprene units, sesquiterpenes have 3, and diterpenes have 4. Steroids are derived from terpenes but have a fused ring structure. Alkaloids contain nitrogen and peptones are protein derivatives.

A peptide bond forms through a condensation reaction between the carboxyl group (-COOH) of one amino acid and the amino group (-NH2) of another amino acid, releasing a water molecule. This is the fundamental bond that links amino acids together in proteins.

Gametophytic self-incompatibility is determined by the haploid genotype of the pollen (gametophyte), whereas sporophytic incompatibility is determined by the diploid genotype of the parent plant (sporophyte). In gametophytic systems, the pollen's own genes control compatibility.

Ti (tumor-inducing) and Ri (root-inducing) plasmids are disarmed by removing disease-causing genes while retaining the T-DNA region for gene insertion. They include selectable markers (antibiotic resistance) and cloning sites for genetic engineering. All three statements correctly describe vector design.

New species formation requires both isolation (geographic, reproductive, or temporal) to prevent gene flow and mutations to create genetic divergence. While competition and variation influence evolution, isolation and mutation are the primary drivers of speciation.

Joseph Koelreuter reported hybrid vigor (heterosis) in his tobacco hybridization experiments in the 1760s, making him one of the first to document the phenomenon. While Shull later developed hybrid corn breeding, Koelreuter's work in tobacco came much earlier.

In Melandrium album (now classified as Silene latifolia), the Y chromosome is longer than X, they form heteromorphic bivalents, and the presence of a Y chromosome determines maleness regardless of the number of X chromosomes. Statement 2 is incorrect because Y and X are heteromorphic (different in size and structure), not homomorphic.

Hershey and Chase (1952) proved that DNA, not protein, is the genetic material using bacteriophages labeled with radioactive isotopes (S-35 for protein, P-32 for DNA). Only the DNA entered bacterial cells, demonstrating nucleic acid is the infectious component.

A double trisome involves two different chromosomes, each present in three copies instead of the normal two copies. This is represented as 2n + 1 + 1, indicating an extra copy of two different chromosomes. A simple trisome would be 2n + 1.

William Bateson proposed the coupling and repulsion hypothesis to explain how alleles from different genes interact. When two dominant alleles are on one chromosome and two recessives on the other (coupling phase), they tend to be inherited together. The opposite arrangement is repulsion. This laid groundwork for linkage theory.

Cytoplasmic male sterility (CMS) is a maternally inherited trait where plants fail to produce functional pollen. The genetic factors responsible for CMS are located in the mitochondrial DNA, not nuclear DNA or chloroplast DNA. Mitochondrial rearrangements or novel chimeric genes interfere with normal pollen development, making this the basis for hybrid seed production in many crops.

When two inbred maize lines are crossed, the F1 generation exhibits heterosis (hybrid vigor), resulting in superior yield and performance. However, when F1 plants are self-pollinated to produce F2, this heterosis is largely lost due to segregation and recombination of alleles, leading to inbreeding depression. The F2 generation shows increased homozygosity and reduced performance compared to the F1 hybrid.

The Respiratory Quotient (RQ = CO2 produced/O2 consumed) depends on substrate composition. Citric acid (C6H8O7) has RQ = 6/7 ≈ 0.86, while lipids typically have RQ around 0.7. Citric acid actually has HIGHER RQ than lipids because it contains more oxygen relative to carbon. Therefore Assertion A is false (citric acid has MORE RQ, not less). Reason R is true (citric acid does have relatively more oxygen than lipids).

Segmental allopolyploids have chromosomes that are partially homologous (some chromosomes pair, others don't). Both statements are true - they do have homologous chromosomes (A is true), and their meiotic behaviour (irregular pairing) is used to identify them (R is true). However, R is not the EXPLANATION of A - meiotic behaviour doesn't cause the chromosomes to be homologous; the homology exists independently and is revealed by meiosis.

  Genes donot follow the law of independent assortment as per Mendel's studies.

Hamilton Smith (along with Daniel Nathans and Werner Arber) discovered restriction endonucleases in the late 1960s, for which they shared the 1978 Nobel Prize in Physiology or Medicine. Smith isolated the first restriction enzyme HindII from Haemophilus influenzae.

Vessels are a characteristic feature of angiosperm wood and are completely absent in all gymnosperms (including all conifers). Ray tracheids (A false) are present in some dicots. Ray parenchyma (B false) is present in gymnosperms. Fibres (C false) are abundant and important in dicot woods.

In a concentric vascular bundle, amphicribal arrangement has phloem surrounding the xylem on all sides. Amphivasal (B) is the reverse - xylem surrounds phloem. Radial (D) refers to arrangement in a cylinder. Closed (A) refers to lack of cambium, not tissue arrangement.

Carrot (Daucus carota) has an umbel inflorescence - flat-topped with flower stalks arising from a common point like umbrella ribs. Catkin is a hanging spike (oak, willow). Corymb is flat-topped but outer flowers have longer stalks. Spike has flowers directly on the main axis without stalks.

9:6:1 is duplicate gene action (two genes with similar effects), 12:3:1 is supplementary gene action (dominant allele at one locus masks expression at another), 9:3:4 is inhibitory gene action (one gene inhibits another), 13:3 is suppressor gene action (one gene suppresses another). The correct matching is A-5, B-4, C-2, D-3.

 The correct option is 1.

 The correct option is 4.

 Calotropis procera is a non-succulent peremnial xerophyte.

 The bulbosum technique used for the production of haploid barley was first given by Guha and Maheswari.

 The correct option is 4.

 The correct option is 2.

 Option 2 is not a correct statement.

 The correct option is 2.

  Asteraceae families has syngenesious anthers and inferior ovary.

 The correct option is 2.

 By the presence of Tetradynamous stamens and replum the family Brassicaceae can be immediately identified.

Ephedraceae is a family of gymnosperms that includes the genus Ephedra, which produces ephedrine. They are non-flowering seed plants with naked seeds, classified in the division Gnetophyta within gymnosperms, not algae, bryophytes, or angiosperms.

 The family Onagraceae is marked out by oenothera type of embryo sac. It is a monosporic embryo sac.

 Ginkgo resembles ferns having reticulated leaves.

Hardin formulated the competitive exclusion principle stating two species competing for same resources cannot coexist. Liebig's law of minimum states growth is limited by the scarcest resource. Shelford's law of tolerance specifies organisms have limits for environmental factors. Whittaker developed the concept of vegetational complexity and classification.

Cucurbits (cucumber, pumpkin, gourd) are monoecious with separate male and female flowers on the same plant. Mango flowers are polygamous-containing both functional stamens and pistils along with sterile forms-classified as having neuter, male and female flowers occurring together in inflorescences.

Bruguiera and Kandelia are true mangrove genera adapted to saline intertidal zones. Eugenia has some mangrove associates but most species are non-mangrove trees. Schima belongs to Theaceae family and is a montane forest tree not found in mangrove ecosystems.

Auxin (IAA) is the primary hormone that stimulates vascular cambium activity and promotes differentiation of cambial derivatives into xylem (secondary growth). Cytokinins promote cell division but not specifically xylem differentiation. ABA inhibits growth; ethylene regulates fruit ripening and senescence.

Climacteric fruits show autocatalytic ethylene production where ethylene stimulates its own biosynthesis. Gibberellins can cause phloem differentiation in stem tissue. Abscisic acid (ABA) production is triggered by water stress and loss of turgor pressure in guard cells. All three statements are physiologically accurate.

Red drop (decrease in photosynthetic efficiency at wavelengths >680 nm) and Emerson enhancement effect (greater than additive photosynthesis when beams of 680 nm and shorter wavelengths are combined) demonstrated existence of two photosystems working in series-PSII and PSI.

In endomycorrhizae, fungal hyphae penetrate root cortex but do NOT pass through Casparian strip-they form arbuscules within cortical cells. Leghemoglobin globin is plant-encoded while heme is bacterial-synthesized (opposite of statement). Both statements as written are actually correct despite seeming counterintuitive.

 The correct option is 4.

The correct answer is 2.

Water-splitting and oxygen evolution occur on lumen side of thylakoid membrane within PSII complexes located in granal stacks. Ferredoxin-NADP reductase (producing NADPH) is bound to stroma-facing side of thylakoid membrane. Both statements correctly describe spatial organization.

Pentose Phosphate Pathway produces erythrose-4-phosphate which is precursor for aromatic amino acids and lignin synthesis. PPP operates in plastids (including chloroplasts). NADPH is generated as oxidative phase product. All three statements are correct.

Geiger-Muller Counter is a radiation detection instrument used for measuring ionizing radiation (radioactivity). Option A duplicates the question text as content. Options C and D refer to botanical techniques unrelated to radiation detection.

The question asks which statement is NOT correct. Lateral roots originate from the pericycle (a layer of cells inside the endodermis), not from the endodermis itself. The other statements are all accurate: roots do produce gibberellins, Casparian strips regulate mineral entry into the xylem, and Rhizobium's nitrogen fixation is powered by host-derived sugars.

Photorespiration begins when RuBP oxygenase produces phosphoglycolate, which is converted to glycolate. Glycolate exits chloroplasts, enters peroxisomes, and is converted to glyoxylate. Glyoxylate then transaminates to glycine. Glycine enters mitochondria, where two molecules combine to form serine, releasing CO2 and NH3. Thus the sequence is: Glycolate → glyoxylate → glycine → serine.

Xenogamy is the correct term for pollination between two different plants (cross-pollination). Geitonogamy is pollination between different flowers on the same plant. Cleistogamy refers to self-pollination without opening flowers. Dichogamy is the temporal separation of male and female reproductive phases in hermaphroditic flowers. The question asks about pollination between flowers on DIFFERENT plants, which matches xenogamy exactly.

Phototropism (bending toward light) in oat coleoptiles is caused by an auxin gradient. Current understanding indicates that auxin redistribution occurs through lateral transport (PIN proteins) rather than differential destruction/synthesis. The dark side accumulates more auxin, causing elongation and bending toward light. While the reason mentions auxin gradients (which is correct), the mechanism described (destruction in light, extra synthesis in dark) is outdated. However, for the level of this question, it may be accepted as explaining the gradient.

Sorosis is a type of multiple fruit that develops from a complete inflorescence (spike or spadix). Examples include pineapple, mulberry, and jackfruit. Option A correctly states that sorosis develops from a spike or spadix. Options B, C, and D describe other fruit types: B refers to berries, C refers to arillus (like pomegranate), and D refers to pome fruits (like apple).

Oak trees are wind-pollinated (anemophilous). They produce inconspicuous flowers with copious, lightweight pollen grains adapted for wind dispersal. Oak pollen is a common allergen because it's wind-borne. Wind pollination is the primary mechanism, not insects, birds, or rain droplets.

Pollen grain walls have two layers: the outer exine (made of sporopollenin, highly resistant) and the inner intine (made of cellulose and pectin, similar to primary plant cell walls). The intine is the cellulose-rich inner layer. Callose is typically involved in pollen tube growth but is not the intine component. Chitin is found in fungal cell walls, not pollen. Sporopollenin makes up the exine, not the intine.

The question asks which is NOT a common feature of gametophytic self-incompatibility (GSI) systems. In GSI, pollen is typically 2-celled (not 3-celled) at release. In vitro germination of GSI pollen is notoriously difficult due to complex recognition mechanisms requiring stylar factors. The pistil is typically dry (not wet) in GSI systems. The rejection reaction often occurs in the style, which IS a common feature. Thus, option D 'In vitro germination of pollen is easy' is NOT a common feature and is the correct answer.

Perisperm is the persistent nucellar tissue that remains in the fertilized ovule. In some seeds like pepper, the nucellus remains as starchy nutritive tissue surrounding the embryo. Endothecium is a layer of anther wall, perithecium is a type of fungal fruiting body, and epistase is not a valid botanical term.

Shorea robusta seeds are recalcitrant - they lose viability quickly (within days to weeks) due to sensitivity to desiccation. Lens esculenta (lentil) seeds are orthodox - they can remain viable for several years when properly dried and stored. Both statements are correct.

Storage proteins in endosperm are mainly prolamins and glutelins (in cereals). Globulins and albumins are storage proteins found in the embryo, not the endosperm. The other pairs are correctly matched: primary endosperm forms from double fertilization, helobial type has cell wall formation after nuclear divisions, and endosperm cell walls contain mannans and xyloglucans.

In corn (maize), the mature seed is albuminous - it retains endosperm tissue. So statement A says it is exalbuminous (no endosperm), which is incorrect. Therefore B (which says the statement is not correct) is the right answer. Orchid embryos indeed lack cotyledons (they are undifferentiated), and corn embryos do contain young leaves.

During pollen maturation and pollination preparation, pollen grains naturally become partially dehydrated, which helps them survive environmental stress. Antipodal cells are ephemeral structures that degenerate after fertilization (or even before it in some species). Both statements are correct.

Rice seeds can germinate under flooded (anaerobic) conditions because their embryos have adapted to carry out facultative anaerobic respiration - they can switch to fermentation when oxygen is limited. The reason correctly explains the assertion.

Laminaria (brown algae) is commercially important as a source of mannitol, a sugar alcohol used as a sweetener and in medicine. Chlorella is used for protein/supplements, Gelidium for agar, and Sargassum for alginate - not primarily for mannitol.

In pear (pome fruit), the fruit develops from an inferior ovary where the floral tube (hypanthium) surrounds the ovary. The edible inner part is the true fruit (from ovary), while the outer flesh is accessory tissue (from hypanthium). Both statements are individually true but the reason (inferior ovary) does not fully explain the tissue classification.

Root knot of sugar-cane (Meloidogyne) and wilt of cotton (Verticillium/Fusarium) are caused by nematodes, not fungi. Angular leaf spot of cotton (Xanthomonas) is bacterial. Only root rot of wheat is fungal (Gaeumannomyces/other fungi). Therefore, 1, 3, and 4 are not caused by fungi.

 Triphenyl tetrazolium chloride, TTC, or simply tetrazolium chloride is a redox indicator commonly used in biochemical experiments especially to indicate cellular respiration.

Evans blue is a vital stain that cannot penetrate live protoplast membranes. Viable protoplasts exclude the dye and remain unstained, while dead/damaged protoplasts take up the blue color. Trypan blue has similar use but Evans blue is more commonly used for protoplasts specifically. Fluorescein diacetate stains viable cells green.

Trapa (water chestnut) is a floating-leaf hydrophyte - its roots are fixed in mud at the bottom, while leaves float on the water surface. Ceratophyllum, Najas, and Utricularia are submerged hydrophytes that float freely or are completely underwater without roots anchored in mud.

In plant embryogenesis, the apical cell of the 2-celled embryo develops into the embryo proper (bulk of the embryo), while the basal cell forms the suspensor and root apex. The torpedo stage shows clear differentiation of root and shoot, and the globular stage precedes cotyledon emergence. This developmental sequence follows the standard pattern in dicot embryogenesis.

Bordeaux mixture is a classic copper-based fungicide composed of copper sulfate and lime. It has been widely used in agriculture since the late 19th century to control fungal diseases on various crops. Carboxin is a systemic fungicide, chloropicrin is a soil fumigant, and mercuric chloride is a mercury-based compound (now largely banned).

Palmarosa oil is extracted from Cymbopogon martinii (also known as Palmarosa grass or rosha grass). It's a valuable essential oil used in perfumery and aromatherapy for its rose-like scent. The other plants listed have different uses: Dryopteris filix-mas is a fern, Ferula asafetida gives asafoetida, and Terminalia chebula is a medicinal tree.

All three statements about polyhydroxybutyrates (PHB) are correct. PHB is indeed produced by bacterial fermentation (e.g., Alcaligenes eutrophus), serves as a biodegradable plastic alternative to conventional plastics, and transgenic plants including trees have been genetically engineered to produce PHB for commercial-scale production. This makes PHB an important sustainable biomaterial.

Bunchy top of banana was introduced from Ceylon (Sri Lanka), and flag smut of wheat came from Fiji. However, potato tuber moth was NOT introduced from Italy - it originated from the Andes region (South America) and spread to India through other routes. This makes pair 2 incorrect, so only pairs 1 and 3 are correctly matched.

Biological control through antagonism involves competition, parasitism and predation.

Lithospermum erythrorhizon (note spelling correction from 'eryghrohizon') cell cultures are commercially used to produce shikonin, a red naphthoquinone pigment with medicinal properties. Shikonin has antimicrobial and anti-inflammatory properties and is used in traditional medicine and cosmetics. Berberine comes from Berberis species, palmitine is also from Berberis, and plumbagin from Plumbago species.

In vitro micropropagation provides year-round availability (independent of seasons), uses very small explants (single cells or meristems), and produces disease-free plants through meristem culture and sterile conditions. However, it does NOT increase the range of variability - in fact, micropropagation produces genetically uniform clones (somaclonal variation is limited and not the primary purpose).

Jatropha curcas is considered a potential petro-crop (biofuel crop) because its seeds contain high oil content (30-40%) suitable for biodiesel production. While Euphorbia tirucalli also produces hydrocarbon-rich latex, Jatropha has been more extensively studied and cultivated for biofuel. Pongamia glabra (Millettia pinnata) and Ricinus communis (castor) are also oil-bearing plants but Jatropha emerged as the primary petro-crop candidate.

Before life, Earth's atmosphere had ammonia, methane, and free hydrogen, but no free oxygen. Free oxygen only appeared after photosynthetic organisms evolved and started producing it as a byproduct.

Louis Pasteur is famous for his swan-neck flask experiments that definitively disproved the theory of spontaneous generation. He showed that microorganisms come from existing microorganisms, not spontaneously from non-living matter.

Cuscuta (dodder) is a total stem parasite (3) that completely lacks chlorophyll. Loranthus is a partial stem parasite (4). Orobanche (broomrape) is a total root parasite (1). Santalum (sandalwood) is a partial root parasite (2).

In ecological succession on bare rocks: Rhizocarpon (crustose lichen) is the pioneer stage (1), followed by Parmelia (foliose lichen) (2), then Polytrichum (moss) (3), and finally Aristida representing the herb stage (4) as soil develops.

 Synizesis refers to a phenomenon sometimes observed in one of the subphases of meiosis. This phenomenon, sometimes referred to as a 'synizetic knot', and contrasted with the chromosome 'bouquet' more typically observed, is characterized by the localization of the meiotic chromosomes in a tight clump on one side of the nucleus.

The delay of senescence of leaves and other organs of the plants by cytokinins is called Richmond Lang effect.

 Orchid seeds lack endosperm but double fertilisation occurs in orchid.

It is true that the rate of DNA replication is much faster in E. coli than in eukaryotes. It is also true that the length of Okazaki fragments that result from DNA Polymerase I activity are much shorter in prokaryotes than in eukaryotes. But R is not the correct explanation of A. 

 The coorect answer is option no.4.

Seed Link maize was engineered for herbicide tolerance (2), Rainbow papaya for virus resistance (1) against papaya ringspot virus, and Flavr Savr tomato had altered ripening (3) via antisense RNA to delay softening.