UPHESC Assistant Professor Agricultural Botany PYQs

Concept: Match each group with its hallmark.

1. Myxobacteria – gliding cells aggregate into multicellular fruiting bodies (a-1).
2. Methylotrophs – use reduced one-carbon compounds (formamide, cyanide, CO, methanol) (b-4).
3. Bacillus subtilis – forms endospores (c-2).
4. Mycoplasma – no cell wall, so penicillin-resistant; mostly parasitic (d-3).

Short trick: No wall → penicillin can't act → Mycoplasma.

Concept: A complete, infectious virus particle (nucleic acid + protein coat) is a virion.

1. Capsid – only the protein coat; nucleocapsid = capsid + nucleic acid.
2. Viroid – naked circular RNA without any protein coat (e.g. PSTVd).

Short trick: Virion = whole virus; capsid = coat only; viroid = RNA only.

Concept: Thiram is a dithiocarbamate – an organic sulphur fungicide (seed dressing).

1. Other dithiocarbamates: ziram, zineb, maneb, mancozeb.
2. Elemental sulphur – inorganic sulphur fungicide.
3. Bordeaux mixture and copper oxychloride – inorganic copper fungicides.

Short trick: Thi-ram, zi-ram, man-cozeb: carbamates = organic S.

Concept: Hyperplasia = overgrowth due to increased cell number (cell division), e.g. crown gall, club root.

1. Hypertrophy = overgrowth due to increased cell size.
2. Necrosis = death of cells/tissue.
3. Damping-off = seedling collapse (Pythium).

Short trick: Plasia = more cells; trophy = bigger cells.

Concept: All genes located on one chromosome form a linkage group; number of linkage groups = haploid chromosome number (n).

1. Linkage – the tendency (phenomenon) of genes to be inherited together.
2. Linkage map – the diagram showing their order and distances (cM).

Short trick: Group = set of genes; linkage = phenomenon; map = diagram.

Concept: An amphidiploid is an allopolyploid with the diploid complement of two or more different genomes; an allotetraploid has exactly two distinct genomes, each doubled (AABB).

1. Amphidiploid – two copies each of two or more genomes (a-2), e.g. hexaploid wheat AABBDD.
2. Allotetraploid – two copies each of two distinct genomes (b-3), e.g. Brassica juncea AABB.
3. Amphoteric – substance of dual (acid + base) nature (c-1).

Short trick: Tetra = exactly two genomes; amphi = two or more.

Concept: Hydroxylamine (NH₂OH) hydroxylates cytosine, which then pairs with A – it produces only GC → AT transitions, never AT → GC.

1. Mustard gas, EMS – alkylating agents.
2. Acridine orange, proflavin – intercalate, causing frameshifts.
3. Nitrous acid – deaminates A, C, G.

Short trick: Hydroxylamine is one-way: GC → AT only.

Concept: W. Johannsen (1903) proposed the pure-line theory working with the Princess variety of French bean (Phaseolus vulgaris) seed weight.

1. Selection is effective only among pure lines, not within a pure line (variation within is environmental).
2. Bulk method – Nilsson-Ehle (1908); backcross – Harlan & Pope (1922); progeny test – Vilmorin.

Short trick: Johannsen – beans – pure line – also coined 'gene', 'genotype', 'phenotype'.

Concept: Norin 10 is a Japanese semi-dwarf wheat carrying Rht1 and Rht2 (Rht-B1b, Rht-D1b) genes.

1. O. Vogel crossed it to produce Gaines; N. E. Borlaug used it to develop Mexican semi-dwarf wheats (Sonora 64, Lerma Rojo 64).
2. Rice dwarfing gene = sd1 from Dee-geo-woo-gen.

Short trick: Norin 10 → wheat; Dee-geo-woo-gen → rice.

Concept: The Golgi apparatus modifies (glycosylates), sorts and packages secretory materials into vesicles.

1. In plants it also synthesises non-cellulosic polysaccharides for the cell plate/wall.
2. Hydrolytic enzymes are held by lysosomes; membrane proteins are made on RER ribosomes.

Short trick: Golgi = cell's post office: pack and dispatch.

Concept: Vesicles are small membrane-bound sacs that temporarily store and carry materials between ER, Golgi and plasma membrane (exo-/endocytosis).

1. Chloroplast – photosynthesis.
2. Lysosome – intracellular digestion.
3. Nucleus – genetic control.

Short trick: Vesicle = cellular courier bag.

Concept: Positively photoblastic seeds (e.g. lettuce cv. Grand Rapids) need red light, which acts via phytochrome to raise GA levels; applied GA₃ replaces this light requirement.

1. GA also substitutes cold (stratification) and long-day requirements in some plants.
2. Red light → Pfr → GA biosynthesis genes (GA3ox) ↑ → hydrolases → germination.

Short trick: Lettuce in the dark + GA = germination.

Concept: C₄ plants are grouped by the bundle-sheath decarboxylating enzyme.

1. NADP-ME type – maize, sugarcane, sorghum (malate shuttled; chloroplasts in bundle sheath).
2. NAD-ME type – Atriplex, Amaranthus, pearl millet (aspartate, mitochondrial).
3. PEP-CK type – Panicum maximum, Chloris.
4. Arabidopsis is a C₃ plant.

Short trick: Maize–Sugarcane–Sorghum = NADP-ME (the 'big three' crops).

Concept: Plant photoreceptors and their main roles.

1. Phytochromes – red/far-red receptors controlling germination, de-etiolation, flowering (a-3).
2. Cryptochromes – blue/UV-A receptors that entrain (reset) the circadian clock (b-2).
3. Phototropins – blue light: phototropism, chloroplast movement, stomatal opening (c-4).
4. Zeitlupe (ZTL) family – circadian period and day-length (photoperiodic) flowering (d-1).

Short trick: Phot = movement (chloroplasts, stomata); Phy = red; ZTL = 'slow motion' clock.

Concept: Photorespiration and carbon fixation take place in different organelles: Rubisco works in the chloroplast stroma; glycine → serine occurs in mitochondria.

1. (A) Glyoxylate → glycine (transamination) – peroxisome: correct.
2. (B) RuBP → 3-PGA (Rubisco carboxylation) – printed site 'Stomata': wrong; it occurs in the chloroplast stroma (stomata only admit CO₂).
3. (C) Glycine → serine – printed site 'Ribosome': wrong; it occurs in mitochondria (glycine decarboxylase + SHMT).
4. (D) Packaging of polysaccharides into vesicles – Golgi bodies: correct.
5. Two pairs (B and C) are not correctly matched, so the question has no single answer as printed.

Short trick: Photorespiration route: Chloroplast (stroma) → Peroxisome → Mitochondrion (Gly → Ser) → Peroxisome → Chloroplast.

Concept: Grey speck of oats (and other cereals) is a manganese-deficiency disorder, common on alkaline/over-limed soils.

1. Other Mn disorders: marsh spot of pea, speckled yellows of sugar beet, pahala blight of sugarcane.
2. Cu – reclamation disease/white tip; Mo – whiptail of cauliflower; B – hollow stem, internal cork.

Short trick: Grey speck & Marsh spot = Manganese (both 'spots').

Concept: Proline is the classic compatible solute accumulated under drought, salinity and cold for osmotic adjustment.

1. It also stabilises proteins/membranes and scavenges ROS.
2. Other osmolytes: glycine betaine, mannitol, trehalose, sugars.

Short trick: Stress → Proline (and glycine betaine).

Concept: The root-hair (maturation) zone has an enormous absorptive surface and is the main site of water and mineral uptake.

1. Root cap – protection, gravity perception.
2. Meristematic zone – cell division.
3. Elongation zone – cell enlargement (some uptake, but not the main site).

Short trick: Hairs = surface = absorption.

Concept: Loam (roughly 40% sand, 40% silt, 20% clay) combines good aeration and drainage with good water and nutrient retention – ideal for most crops.

1. Sandy soil – poor water/nutrient holding.
2. Clay – poor aeration, waterlogging, hard when dry.
3. Silt alone – crusting, poor structure.

Short trick: Loam = balanced = best.

Concept: Tilth is the physical condition of soil resulting from tillage – crumbly, well-aerated – suitable for a good seed bed.

1. Tillage is the operation (process); tilth is its result (condition).
2. Blade harrow – an implement; furrow – a trench made by a plough.

Short trick: Tillage = action, Tilth = condition.