ICAR AIEEA UG Practice Set 1

Explanation: A rain gauge (also called udometer or pluviometer) is the standard instrument used to measure the amount of liquid precipitation over a set period of time in a specific area.

Explanation: Heterosis (hybrid vigour) is the superiority of the F1 hybrid over both parents in terms of yield, vigour, and other desirable characters. It was first described by Shull in 1908.

Explanation: Rhizobium bacteria form a symbiotic relationship with leguminous plants (family Fabaceae/Leguminosae) such as pea, soybean, groundnut, and lentil. They colonize root nodules and fix atmospheric nitrogen into ammonia using the enzyme nitrogenase.

Explanation: Holstein Friesian is the world's highest milk-producing dairy cattle breed, originating from the Netherlands. A single cow can produce over 10,000 litres of milk per year under good management.

Explanation: Di-ammonium phosphate (DAP) contains 18% nitrogen and 46% phosphorus (as P2O5) with no potassium, giving an N:P:K ratio of 18:46:0. It is the most widely used phosphatic fertiliser in India.

Explanation: Inarching (approach grafting) is commonly used in mango propagation, especially for varieties that are difficult to propagate by other grafting methods. In this technique, both the stock and scion remain attached to their parent plants until the graft union is established.

Explanation: In backcross breeding, the recurrent parent is the agronomically superior variety to which the hybrid is repeatedly crossed back. The aim is to transfer one or a few desirable genes from the donor parent while recovering the genotype of the recurrent parent.

Explanation: Carolus Linnaeus introduced the binomial system of nomenclature in his work 'Species Plantarum' (1753). Under this system, every organism is given a two-part Latin name consisting of the genus and species epithet.

Explanation: Chlorophyll-a is the primary photosynthetic pigment in green plants. It directly participates in the light reactions of photosynthesis by absorbing light energy (mainly red and blue wavelengths) and converting it to chemical energy.

Explanation: Haemoglobin is the iron-containing oxygen-carrying metalloprotein found in red blood cells. Each haemoglobin molecule can bind up to four oxygen molecules, forming oxyhaemoglobin for transport from the lungs to tissues.

Explanation: Double fertilisation is unique to angiosperms (flowering plants). One sperm fuses with the egg cell to form the zygote (syngamy), and the second sperm fuses with the two polar nuclei to form the triploid primary endosperm nucleus (triple fusion).

Explanation: The Hardy-Weinberg equilibrium states that allele and genotype frequencies remain constant in the absence of evolutionary forces: no mutation, random mating, no natural selection, infinitely large population size, and no gene flow (migration).

Explanation: A climax community is the final, stable stage of ecological succession. It is characterised by maximum species diversity, complex food webs, and a stable biomass where the community is in equilibrium with its environment.

Explanation: According to Avogadro's law, one mole of any ideal gas at standard temperature and pressure (0°C and 1 atm) occupies a volume of 22.4 litres. This is known as the molar volume.

Explanation: In ethylene (C₂H₄), each carbon atom is sp² hybridised, forming three sigma bonds (two with hydrogen atoms and one with the other carbon) in a trigonal planar arrangement, with one unhybridised p-orbital forming the pi bond of the double bond.

Explanation: Tollen's reagent (ammoniacal silver nitrate) distinguishes aldehydes from ketones. Aldehydes reduce Ag⁺ to metallic silver (forming a silver mirror), while ketones do not react. This is because aldehydes are more easily oxidised than ketones.

Explanation: For a first-order reaction, rate = k[A]. Since rate has units of mol L⁻¹ s⁻¹ and [A] has units of mol L⁻¹, the rate constant k has units of s⁻¹ (time inverse). This is independent of concentration units.

Explanation: Peptide bonds link amino acids in proteins. A peptide bond is formed by a condensation reaction between the carboxyl group (–COOH) of one amino acid and the amino group (–NH₂) of the next, releasing a molecule of water.

Explanation: Colligative properties depend only on the number (mole fraction) of solute particles in the solution, not on their chemical nature or identity. Boiling point elevation is directly proportional to the molal concentration of the solute.

Explanation: Using v² = u² − 2gh, at maximum height v = 0: 0 = (20)² − 2(10)h, so h = 400/20 = 20 m.

Explanation: Kinetic energy = ½mv² = ½ × 2 × 5² = ½ × 2 × 25 = 25 J.

Explanation: The second law of thermodynamics introduces the concept of entropy, which is a measure of the disorder or randomness of a system. It states that in any spontaneous process, the total entropy of an isolated system always increases.

Explanation: In single slit diffraction, the first minimum occurs at sinθ = λ/a, where a is the slit width. The central maximum extends from −λ/a to +λ/a, making its angular width 2λ/a.

Explanation: Ohm's law states that the current (I) flowing through a conductor is directly proportional to the potential difference (V) across it, provided the temperature and other physical conditions remain constant: I = V/R.

Explanation: The time period of a simple pendulum is T = 2π√(l/g), where l is the length of the pendulum and g is the acceleration due to gravity. It is independent of the mass of the bob and amplitude (for small oscillations).

Explanation: Using the Pythagorean identity sin²θ + cos²θ = 1: cos²θ = 1 − (3/5)² = 1 − 9/25 = 16/25, so cos θ = 4/5 (taking the positive value for an acute angle).

Explanation: The intersection of two sets A ∩ B contains all elements that are common to both A and B. The elements common to {1, 2, 3} and {2, 3, 4} are 2 and 3.

Explanation: Sum of first 10 natural numbers = 10 × 11/2 = 55. Mean = 55/10 = 5.5.

Explanation: ∫₀¹ x² dx = [x³/3]₀¹ = 1³/3 − 0³/3 = 1/3.