UPCATET flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Cropping intensity
- Percentage ratio of gross cropped area to net sown area in a year; values above 100% indicate more than one crop harvested on the same land.
- Critical period of weed competition
- The growth window during which weed infestation most reduces crop yield, typically the first 30 to 45 days after sowing in most annual field crops.
- Vernalization
- Exposure of germinating seeds or young seedlings to low temperature, required by crops such as winter wheat and sugar beet to induce flowering.
- Parthenocarpy
- Development of fruit without fertilization, producing seedless fruit; can be induced artificially by gibberellic acid sprays in grape and citrus.
- Chilling hours
- Cumulative hours between 0 and 7.2 degrees Celsius needed to break bud dormancy in temperate fruit trees such as apple.
- Nucellar embryony
- Formation of embryos from nucellar tissue in citrus, giving seedlings genetically identical to the mother plant and useful for rootstock breeding.
- Economic threshold level
- Pest population density at which control measures should be initiated to prevent the pest from reaching the economic injury level.
- Bt toxin mechanism
- Cry proteins from Bacillus thuringiensis dissolve in the alkaline insect gut and create pores in midgut cells, killing lepidopteran larvae.
- Trichoderma as biocontrol
- Soil fungus used as an antagonistic biological control agent against soil-borne pathogens, working through mycoparasitism and induced plant resistance.
- Cation exchange capacity
- Total quantity of exchangeable cations a soil can hold, expressed in centimoles of charge per kilogram; higher in montmorillonite clays and organic matter.
- Field capacity
- Water content remaining in soil after free drainage, held at about minus 0.33 bar suction; the upper limit of plant-available water.
- Bulk density
- Oven-dry mass of soil divided by its total volume including pore space, typically 1.1 to 1.6 grams per cubic centimetre for mineral soils.
- Critical angle
- Angle of incidence beyond which light travelling from a denser to a rarer medium undergoes total internal reflection; given by sin θc = n2/n1.
- Work-energy theorem
- The net work done on an object equals its change in kinetic energy, valid for both constant and variable forces.
- Carnot efficiency
- Maximum efficiency of a heat engine operating between hot and cold reservoirs, equal to one minus the ratio of cold to hot absolute temperatures.
- Le Chatelier's principle
- When a system at equilibrium is disturbed by changes in concentration, pressure or temperature, it shifts to partially oppose that change.
- Markovnikov's rule
- In addition of hydrogen halide to an unsymmetrical alkene, the hydrogen adds to the carbon atom bearing the greater number of hydrogen atoms.
- Molarity
- Concentration expressed as moles of solute dissolved per litre of solution; temperature-dependent because solution volume changes with temperature.
- Discriminant of a quadratic
- The quantity b squared minus 4ac for ax squared plus bx plus c; positive gives two real roots, zero gives equal roots, negative gives complex roots.
- Sum of a geometric progression
- For first term a and common ratio r not equal to one, the sum of n terms is a times (r to the power n minus one) divided by (r minus one).
- Conditional probability
- Probability of event A given that B has occurred, equal to the probability of A and B both occurring divided by the probability of B.
- Double fertilization
- In angiosperms one sperm fuses with the egg to form the zygote while another fuses with two polar nuclei to form triploid endosperm.
- Pressure-flow hypothesis
- Explanation of phloem transport in which sugars move from source to sink driven by a pressure gradient created by osmotic water movement.
- Abscisic acid function
- Plant hormone that promotes stomatal closure during water stress, maintains seed dormancy and inhibits growth, acting as a stress signal.
- Loop of Henle role
- Nephron segment that creates a concentration gradient in the renal medulla, enabling production of concentrated urine under antidiuretic hormone.
- Mendel's law of segregation
- The two alleles of a gene separate during gamete formation so that each gamete carries only one allele of each gene pair.
- Saltatory conduction
- Rapid jumping of nerve impulses between nodes of Ranvier along myelinated axons, greatly increasing conduction velocity compared with unmyelinated fibres.
- Syllogism validity rule
- A conclusion is valid only if it is true in every possible Venn diagram consistent with the given premises, not merely in one arrangement.
- Average speed for equal distances
- When equal distances are covered at speeds x and y, average speed equals twice the product of x and y divided by their sum.
- Subject-verb agreement with one of
- In the construction one of the plus a plural noun, the verb agrees with one and is therefore singular, as in one of the boys is here.
- PM-KISAN benefit
- Central scheme giving eligible landholding farmer families income support of 6000 rupees per year, paid in three equal instalments.
- e-NAM platform
- National Agriculture Market, an online trading portal that links regulated wholesale markets so farmers can sell produce across states.