Carbon dioxide ($CO_2$): Directly respired by animals but constitutes part of the short-term biogenic carbon cycle (rapidly re-absorbed by feed crops through photosynthesis), making direct livestock $CO_2$ a non-significant net anthropogenic greenhouse driver compared to enteric methane and nitrous oxide. (Correct answer)
Methane ($CH_4$): A potent greenhouse gas heavily produced by enteric fermentation in ruminants and anaerobic manure lagoons.
Nitrous oxide ($N_2O$): An exceptionally potent greenhouse gas emitted during the storage, handling, and application of livestock manure and urine.
Ammonia ($NH_3$): A significant livestock-related atmospheric pollutant and indirect greenhouse contributor causing soil acidification.
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Calcareous or alkaline soils: Under high pH ($pH \gt 7.5$) and abundant free calcium carbonate ($CaCO_3$), iron precipitates into insoluble ferric hydroxides and carbonates ($Fe(OH)_3$), severely reducing bioavailable $Fe^{2+}$ and triggering characteristic lime-induced iron chlorosis in young leaves. (Correct answer)
Salt affected soils: Primarily induce osmotic drought and specific ion toxicities (excess $Na^+$ and $Cl^-$).
Acidic soils: Low pH increases iron solubility, frequently causing iron toxicity rather than deficiency.
Neutral soils: Offer optimal micronutrient availability without precipitation.
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18
ICAR JRF Forestry 29 Jun 2024Shift 1
MCQ (Single Correct)+4−1
Which of the following is responsible for eliminating toxic oxygen by-products from cells?
Peroxisomes: Specialized microbodies containing antioxidant enzymes such as catalase, peroxidase, and superoxide dismutase that detoxify hazardous reactive oxygen species (ROS), including breaking down toxic hydrogen peroxide ($H_2O_2$) into water and oxygen. (Correct answer)
Mitochondria: The powerhouses of eukaryotic cells primarily responsible for cellular respiration, the Krebs cycle, and ATP synthesis via oxidative phosphorylation.
Golgi complex: Organelles functioning in post-translational modification, sorting, packaging, and secretory targeting of proteins and lipids synthesized in the endoplasmic reticulum.
Chloroplasts: Double-membrane semi-autonomous plastids in photosynthetic plant cells responsible for light capture, photolysis of water, and carbon fixation (Calvin cycle).
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Allyl isothiocyanate: The volatile sulfur-containing organic compound responsible for the characteristic pungent smell and biting taste of mustard oil. It is formed when the glucosinolate sinigrin undergoes enzymatic hydrolysis by myrosinase upon cellular crushing. (Correct answer)
Amino acids: Nitrogenous organic compounds that serve as the building blocks of proteins and do not impart volatile pungency.
Erucic acid: A long-chain monounsaturated fatty acid (C22:1) present in mustard seed triglycerides that affects nutritional oil quality, not volatile aroma.
Oxalic acid: An organic dicarboxylic acid found in leafy greens like spinach that acts as an antinutrient, unrelated to mustard pungency.
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Short day plants (SDPs): Physiologically "long-night plants" (e.g., rice, soybean, chrysanthemum) that require an uninterrupted dark period exceeding a critical duration to induce flowering. If this critical night period is interrupted by even a brief flash of light, flowering is completely inhibited. (Correct answer)
Long day plants (LDPs): Require photoperiods longer than a critical daylength (or short nights) to trigger floral induction (e.g., wheat, oat).
Day neutral plants (DNPs): Initiate flowering after reaching vegetative maturity without dependence on night or day length (e.g., tomato, sunflower).
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