CUET Agriculture Practice Set 1

Explanation: The recommended seed rate for transplanted rice (paddy) is approximately 20-25 kg/ha for the nursery to transplant one hectare of main field. Direct-seeded rice requires a higher seed rate of 80-100 kg/ha.

Explanation: Nitrogen deficiency causes yellowing (chlorosis) of older leaves first because nitrogen is a mobile nutrient in plants and is translocated from older to younger leaves. Severe deficiency leads to stunted growth and reduced tillering.

Explanation: Neem-coated urea slows down the release of nitrogen by acting as a nitrification inhibitor. This reduces nitrogen losses through leaching and volatilisation, improves nitrogen use efficiency, and ensures a longer supply of nitrogen to crops.

Explanation: The concept of Economic Threshold Level was introduced by Stern et al. in 1959. ETL is the pest density at which control measures should be initiated to prevent the pest population from reaching the Economic Injury Level (EIL) where crop losses exceed the cost of control.

Explanation: Monopsony is a market structure where there is only one buyer for a product from many sellers. In agriculture, this can occur when a single processing company is the only buyer of a crop in a region, giving it disproportionate power to set prices.

Explanation: Krishi Vigyan Kendras (Farm Science Centres) are coordinated by the Indian Council of Agricultural Research (ICAR). The first KVK was established in 1974 at Puducherry. There are over 730 KVKs across India, serving as frontline extension centres for technology assessment, refinement, and demonstration.

Explanation: Arthropods are characterised by jointed appendages (arthro = joint, poda = foot), a chitinous exoskeleton, segmented body, and an open circulatory system. It is the largest phylum in the animal kingdom, including insects, arachnids, and crustaceans.

Explanation: Semi-conservative replication means that each new DNA molecule consists of one original (parental) strand and one newly synthesised strand. This was experimentally proven by Meselson and Stahl in 1958 using N-15 labelled DNA in E. coli.

Explanation: The C4 pathway (Hatch-Slack pathway) is found in tropical grasses like maize, sugarcane, and sorghum. The first stable product is a 4-carbon compound (oxaloacetate). C4 plants have higher photosynthetic efficiency and minimal photorespiration compared to C3 plants.

Explanation: Adrenaline (epinephrine), secreted by the adrenal medulla, triggers the 'fight or flight' response. It increases heart rate, blood pressure, and blood glucose levels, dilates bronchioles, and redirects blood flow to skeletal muscles, preparing the body for emergency action.

Explanation: Charles Elton first described ecological pyramids (also called Eltonian pyramids) in 1927. These pyramids graphically represent the trophic structure of an ecosystem in terms of number, biomass, or energy at successive trophic levels.

Explanation: Golden Rice has been genetically engineered to produce beta-carotene (provitamin A) in the edible part of the grain. It was developed to address Vitamin A deficiency, which is prevalent in developing countries that rely on rice as a staple food.

Explanation: At 25°C, the ion product of water (Kw) is 1 × 10⁻¹⁴. In a neutral solution, [H⁺] = [OH⁻] = 1 × 10⁻⁷ M. Therefore, pH = −log(1 × 10⁻⁷) = 7.

Explanation: Noble gases have completely filled outermost electron shells (ns²np⁶, except He which has 1s²). This gives them maximum stability and very low reactivity. Elements tend to gain, lose, or share electrons to achieve this stable configuration (octet rule).

Explanation: Markovnikov's rule states that in the addition of HX to an unsymmetrical alkene, the hydrogen adds to the carbon with more hydrogen atoms and the halide adds to the carbon with fewer hydrogen atoms. This applies to asymmetric alkenes like propene (CH₃CH=CH₂).

Explanation: The Rydberg constant (R∞ = 1.097 × 10⁷ m⁻¹) was originally derived from the hydrogen emission spectrum. It appears in the Rydberg formula which predicts the wavelengths of spectral lines of hydrogen and hydrogen-like (single-electron) species.

Explanation: The law of conservation of momentum states that the total momentum of an isolated system (no external forces) remains constant. In a collision, the total momentum before the collision equals the total momentum after, regardless of whether the collision is elastic or inelastic.

Explanation: An isothermal process occurs at constant temperature. For an ideal gas undergoing an isothermal process, the internal energy remains constant (ΔU = 0), and the work done by the gas equals the heat absorbed (W = Q), according to the first law of thermodynamics.

Explanation: The work function (φ) is the minimum energy required to eject an electron from the surface of a metal. If the energy of an incident photon (hν) exceeds the work function, the excess energy appears as the kinetic energy of the emitted electron: KE = hν − φ.

Explanation: Using Coulomb's law: F = kq₁q₂/r² = 9×10⁹ × (2×10⁻⁶)² / (0.1)² = 9×10⁹ × 4×10⁻¹² / 0.01 = 36×10⁻³ / 0.01 = 3.6 N.

Explanation: 'Enthusiastic' means showing intense and eager enjoyment or interest. It correctly fits the context of a farmer expressing positive feelings about a new system. 'Enthusiasm' is a noun form, not an adjective.

Explanation: Option C is correct because the subject 'each' is singular and takes the singular verb 'was'. 'Their' is now accepted as a gender-neutral singular pronoun. Options A and B have subject-verb agreement errors, and D uses the wrong form.

Explanation: 'Ameliorate' means to make something better or to improve. It comes from the Latin 'melior' meaning better. It is commonly used in formal contexts such as 'ameliorate soil conditions' or 'ameliorate poverty'.

Explanation: The passage specifically discusses drip irrigation, its mechanism, and its water-saving benefits compared to flood irrigation, making 'Drip Irrigation: Efficient Water Use' the most appropriate and comprehensive title.

Explanation: If the ratio is 3:5, let the numbers be 3x and 5x. Then 3x + 5x = 48, so 8x = 48, hence x = 6. The larger number = 5x = 5 × 6 = 30.

Explanation: Each letter is shifted forward by 1 position in the alphabet: P→Q, L→M, A→B, N→O, T→U. Applying the same rule to FIELD: F→G, I→J, E→F, L→M, D→E = GJFME.

Explanation: The FAO is a specialized agency of the United Nations with its headquarters in Rome, Italy. It was established on 16 October 1945 (celebrated as World Food Day) and leads international efforts to defeat hunger.

Explanation: The logical agricultural sequence is: Ploughing (land preparation) → Sowing (seed placement) → Irrigation (water supply) → Harvesting (crop collection). This follows the natural chronological order of crop production.

Explanation: Average speed = Total distance / Total time = 240 km / 4 hours = 60 km/h.

Explanation: Sexual reproduction involves the fusion (syngamy) of male and female gametes to form a zygote. This process introduces genetic variation in the offspring, unlike asexual reproduction which produces genetically identical clones.