MP PAT flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Crown root initiation stage

In wheat this stage occurs about 20–25 days after sowing and is the most critical for irrigation; water stress here sharply reduces tillering and final grain yield.

Khaira disease of rice

A disorder caused by zinc deficiency, showing rusty-brown patches on middle leaves and stunted tillering; it is corrected by soil application of zinc sulphate or a 0.5% foliar spray.

Whiptail of cauliflower

A molybdenum deficiency in which the leaf blade fails to develop and only the midrib remains, giving a whip-like appearance; corrected by molybdenum application or liming acidic soil.

Gestation period of buffalo

About 310 days, roughly a month longer than cattle at about 280 days; knowing it helps schedule drying-off, calving and the next breeding cycle.

Economic threshold level

The pest population density at which control measures must be started to prevent the population from reaching the economic injury level, where crop loss exceeds control cost.

Seed rate formula

Seed rate in kg/ha equals target plants per hectare multiplied by 1000-grain weight in grams, divided by 1000 × germination fraction × purity fraction.

Benefit-cost ratio

Gross return divided by the total cost of cultivation; a value above 1.0 indicates profit, and the ratio is used to compare alternative technologies or crops.

ATMA

Agricultural Technology Management Agency, a district-level autonomous body for decentralised extension planning that links research, extension and farmers through block-level Farm Information and Advisory Centres.

Escape velocity

The minimum speed, about 11.2 km/s from the earth's surface, needed for a body to escape the earth's gravitational field; it equals √(2gR) and is independent of the body's mass.

Lens formula

1/f = 1/v − 1/u with Cartesian sign conventions; focal length is positive for a convex lens and negative for a concave lens, and magnification m = v/u.

Parallel resistance

For resistors in parallel, the reciprocal of the equivalent resistance equals the sum of the reciprocals of individual resistances, so the equivalent is smaller than the smallest resistor.

Photoelectric equation

hν = φ + Kmax, where φ is the work function and Kmax the maximum kinetic energy of emitted electrons; no emission occurs below the threshold frequency regardless of intensity.

Dimensional formula of force

Force has dimensions [MLT⁻²], obtained from mass × acceleration; from it, work and energy are [ML²T⁻²] and power is [ML²T⁻³].

Newton's second law

The rate of change of momentum of a body is proportional to the applied force and takes place in the force's direction; for constant mass this is F = ma.

Henderson–Hasselbalch equation

pH = pKa + log([salt]/[acid]) for an acidic buffer; it shows that a buffer resists pH change best when the acid and salt concentrations are equal.

Molarity

The number of moles of solute dissolved per litre of solution; it is temperature dependent because solution volume expands or contracts, unlike molality based on solvent mass.

Le Chatelier's principle

When a system at equilibrium is disturbed by a change in concentration, pressure or temperature, it shifts in the direction that partially counteracts the change.

Iodoform test

Warming a compound with iodine and sodium hydroxide gives a yellow precipitate of iodoform, a positive test for ethanol and for methyl ketones such as acetone.

Hybridisation from steric number

Steric number equals sigma bonds plus lone pairs on the central atom: 2 gives sp, 3 gives sp², 4 gives sp³, 5 gives sp³d and 6 gives sp³d².

Nernst equation

E = E° − (0.0591/n) log Q at 298 K, relating cell potential to standard potential and reaction quotient; a positive E°cell means the reaction is spontaneous.

Calvin cycle

The light-independent phase of photosynthesis in the stroma, where RuBisCO fixes carbon dioxide into 3-phosphoglycerate; each carbon dioxide fixed costs three ATP and two NADPH.

Monohybrid F2 ratio

In Mendel's monohybrid cross the F2 phenotypic ratio is 3:1 dominant to recessive, while the genotypic ratio is 1 homozygous dominant : 2 heterozygous : 1 homozygous recessive.

Abscisic acid

The plant stress hormone that closes stomata during water shortage, promotes seed dormancy and abscission, and opposes the growth-promoting action of auxin and gibberellin.

Central dogma

The flow of genetic information from DNA to RNA by transcription and from RNA to protein by translation; base pairing is A with T and G with C on antiparallel strands.

Ten percent law

Only about ten percent of the energy at one trophic level is transferred to the next, which limits food chains to four or five levels and keeps energy pyramids upright.

AB blood group

Blood group AB carries both A and B antigens on red cells and has no anti-A or anti-B antibodies in plasma, making it the universal recipient for transfusion.

Discriminant of a quadratic

For ax² + bx + c = 0 the discriminant is D = b² − 4ac; D > 0 gives two distinct real roots, D = 0 equal real roots and D < 0 complex conjugate roots.

Sum and product of roots

For ax² + bx + c = 0, the sum of roots α + β equals −b/a and the product αβ equals c/a; the quadratic with these roots is x² − (α + β)x + αβ = 0.

General term of binomial expansion

In the expansion of (a + b)ⁿ, the general term is T(r+1) = nCr · a^(n−r) · b^r, and the expansion contains n + 1 terms in total.

Sum of n terms of AP

For an arithmetic progression with first term a and common difference d, Sn = n/2[2a + (n − 1)d], and the nth term is a + (n − 1)d.

Derivative of sine and cosine

d/dx(sin x) = cos x and d/dx(cos x) = −sin x; combined with the chain rule these give derivatives of composite trigonometric functions.

Perpendicular lines condition

Two straight lines are perpendicular when the product of their slopes equals −1, that is m₁m₂ = −1; parallel lines instead satisfy m₁ = m₂.