Plant Pathology — Part 1 MCQs with Explanations

The C : N ratio of sawdust is 225 : 1. Organic matter that is deposited in marine sediments contains a key indicator as to its source and the processes it underwent before reaching the floor as well as after deposition, its carbon to nitrogen ratio. A carbon-to-nitrogen ratio (C/N ratio or C : N ratio) is the ratio of the mass of carbon to the mass of nitrogen in organic residues. It is other things that, be used in analyzing sediments and soil including soil organic matter and soil amendments such as compost.

The nutrient with a key role in biological N-fixation is Molybdenum. Nitrogen fixation is a chemical process by which molecular nitrogen (N 2 ), with a strong triple covalent bond, in the air is converted into ammonia (NH 3 ) or related nitrogenous compounds. The conversion of N 2 into ammonia occurs at a metal cluster called FeMoco, an abbreviation for the iron-molybdenum cofactor. Molybdenum-dependent nitrogenase is the most commonly present nitrogenase.

Zn element is not the major nutrient element. Zinc is a micronutrient for plants, require in less quantity for growth and development. Zinc participates in chlorophyll formation, and also activates many enzymes. Symptoms of zinc deficiency include chlorosis and stunted growth.

Cyanobacteria photosynthetic bacteria possess both PS I and PS II. Cyanobacteria are photosynthetic microorganisms that are abundant in nature. There are two types of photosystems in cyanobacteria, algae, and higher plants, called photosystem I (PSI, plastocyanin-ferredoxin oxidoreductase) and photosystem II (PSII, water-plastoquinone oxidoreductase), both of which are multisubunit membrane complexes.

The most striking symptom of false smut of rice (Claviceps oryzae-sativae) is the Transformation of individual kernels into large, velvety, green balls, Sometimes the size of the kernel is more than twice the diameter of the normal grain, and also the colour of the kernels finally changes to greenish black. False smut causes chalkiness of grains which leads to a reduction in grain weight. It also reduces seed germination. Plants infected with false smut have individual rice grains transformed into a mass of spore balls. These spore balls are initially orange and then turn greenish black when these mature.

Margosa is a highly effective product in reducing the root-knot population belonging to Azadirachta indica. Azadirachta indica, commonly known as neem, nimtree, or Indian lilac, also known as Margosa is a tree in the mahogany family Meliaceae. Root-knot nematodes are one of the plant-damaging nematodes in agriculture causing a projected annual yield loss of 12% worldwide. These nematodes burrow into the soft tissues of root tips and young roots and cause the nearby root cells to divide and enlarge. Neem is effective in reducing root-knot nematode population.

The richest source of nitrogen is Dried blood. A blood meal is a dry, inert powder made from blood, used as a high-nitrogen organic fertilizer and a high-protein animal feed. N = 13.25%, P = 1.0%, K = 0.6%. It is one of the highest non-synthetic sources of nitrogen. It usually comes from cattle or hogs as a slaughterhouse by-product.

A photosynthetic organism that does not release oxygen is a green sulphur bacterium. These bacteria are a phylum of obligately anaerobic photoautotrophic bacteria that metabolize sulfur. Green sulfur bacteria are nonmotile and capable of anoxygenic photosynthesis. They live in anaerobic aquatic environments. In contrast to plants, green sulfur bacteria mainly use sulfide ions as electron donors. They are autotrophs that utilize the reverse tricarboxylic acid cycle to perform carbon fixation.

a. R. lupine in Lupine group. They can fix nitrogen from the atmosphere into ammonia via a rhizobium root nodule symbiosis, fertilizing the soil for other plants. This adaptation allows lupins to be tolerant of infertile soils and capable of pioneering change in barren and poor-quality soils. b. R.trifoli in Clover group. Clover or trefoil are common names for plants of the genus Trifolium consisting of about 300 species of flowering plants. c. R. japonicum and Soybean. Soybean plants to get their necessary dose of nitrogen, partner with bacteria called rhizobium japonicum which can convert atmospheric nitrogen into organic forms the plant can use. d. R. mcliloti and Alfa alfa. R. mclloti is an aerobic, Gram-negative, and diazotrophic species of bacteria. S. meliloti are motile and possess a cluster of peritrichous flagella. S. meliloti fix atmospheric nitrogen into ammonia for their legume symbionts, such as alfalfa.

Interveinal chlorosis occurs due to a deficiency of Iron. Interveinal chlorosis, often called iron chlorosis can be caused by a deficiency of several micro-nutrients; Iron, Zinc, and Manganese, all of which the symptoms look similar. The yellowing of the leaves can be caused by several cultural or environmental issues.

During the formation of pollen grains, a microspore mother cell undergoes one meiotic division. The development of pollen grains takes place in the anther. Pollen development begins when specialized cells (microsporocytes) differentiate in young anthers. There are generally hundreds or thousands of microsporocytes per anther and each passes through meiosis to produce four haploid microspores.

The share of urea in the N production pattern is 85%. While India uses many types of fertilizers, urea accounts for most of the consumption of N and DAP for most of that of P 2 O 5 . Urea accounts for 85 percent of the total consumption of straight N fertilizers.

The formula for chlorophyll a is C 55 H 72 O 5 N 4 Mg. Chlorophyll is any of several related green pigments found in cyanobacteria and the chloroplasts of algae and plants. Chlorophyll allows plants to absorb energy from light. All are defined as derivatives of the parent chlorin by the presence of a fifth, ketone-containing ring beyond the four pyrrole-like rings. The only difference between chlorophyll a and chlorophyll b is that the former has a methyl group whereas the latter has a formyl group. This difference causes a considerable difference in the absorption spectrum, allowing plants to absorb a greater portion of visible light.

Dispersal of spores by a human is known as Anthropochory. The dispersal of seeds, spores, or other reproductive botanical material, or reproductively capable animals, by humans as a routine means of reproductive dispersal of that species. Human dispersers differ from animal dispersers by having much higher mobility, based on the technical means of human transport. Humans may disperse seeds by many various means and some surprisingly high distances have been repeatedly measured.

ATP is injected in cyanide poisoning because it is necessary for cellular functions. Plants have an alternative electron transfer pathway available that passes electrons directly from ubiquinone to O 2 , which confers cyanide resistance by bypassing COX. ATP is the power currency of a cell and it is injected in cyanide poisoning as it breaks down cyanide, necessary for the proper functioning of the cell.

Constituents of pigment system I are located on the outer surface of granal and stromal thylakoids. Photosynthetic pigments are the molecules responsible for absorbing electromagnetic radiation, transferring the energy of the absorbed photons to the reaction center, and for photochemical conversion in the photosynthetic systems of organisms capable of photosynthesis. The pigment system I (PSI) complex consists of 200 chlorophylls, 50 carotenoids and a molecule of chlorophyll an absorbs light at 700 nm (P700) and this constitutes the reaction center of photosystem I.

Phytoplasma was 1 st observed in Mulberry dwarf. Phytoplasmas were discovered in 1967 by Japanese scientists who termed them mycoplasma-like organisms. Phytoplasmas can be found as far back as 1603 in mulberry dwarf disease in Japan. Such diseases were originally thought to be caused by viruses, which, like phytoplasmas, require insect vectors, and cannot be cultured.

Hybridoma technology is used to produce monoclonal antibodies. Hybridoma technology is one of the most common methods used to produce monoclonal antibodies. In this process, antibody-producing B lymphocytes are isolated from mice after immunizing the mice with specific antigens and are fused with immortal myeloma cell lines to form hybrid cells, called hybridoma cell lines.

The mineralization of organic phosphorus has been studied about C/N/P ratio. Mineralization is a process through which organic phosphorus in soil is converted into inorganic phosphorus with the help of soil microbes. Immobilization, on the other hand, is the reverse of mineralization. Organic matter is initially synthesized in aquatic ecosystems mostly through algal photosynthesis, and the C : N : P. the ratio is well known to be close to the Redfield ratio. However, during the decomposition of organic matter, the behavior and the rates of mineralization of C, N, and P can vary.

Cytochrome is a Fe-containing porphyrin pigment. Cytochromes are redox-active proteins containing a heme, with a central Fe atom at its core, as a cofactor. They are involved in the electron transport chain and redox catalysis. Cytochrome function is linked to the reversible redox change from ferrous (Fe(II)) to the ferric (Fe(III)) oxidation state of the iron found in the heme core.

The spores which are produced typically by the binucleate mycelium and mainly function as repeating spores for the spread of rust disease in wheat are called Uredospores. Urediniospores (or uredospores) are thin-walled spores produced by the uredium, a stage in the life cycle of rusts. Urediniospores usually have two dikaryotic nuclei within one cell. In mass, they are usually pale brown in contrast to teliospores which are generally dark brown.

Bacterial cell division is mainly by Binary fission. Binary fission is asexual reproduction by a separation of the body into two new bodies. In the process of binary fission, an organism duplicates its genetic material, or deoxyribonucleic acid (DNA), and then divides into two parts (cytokinesis), with each new organism receiving one copy of DNA. Most bacteria rely on binary fission for propagation. As this is a simple process; a cell just needs to grow to twice its starting size and then split in two.

The process of photophosphorylation was discovered by Arnon. Cyclic photophosphorylation occurs in both aerobic and anaerobic conditions, driven by the main primary source of energy available to living organisms, which is sunlight. In photophosphorylation, light energy is used to pump protons across a biological membrane, mediated by the flow of electrons through an electron transport chain. This stores energy in a proton gradient.

C 4 plants belong to Monocots and Dicots. C 4 carbon fixation is one of three known photosynthetic processes of carbon fixation in plants. About 8,100 plant species use C 4 carbon fixation, which represents about 3% of all terrestrial species of plants. C 4 carbon fixation is more common in monocots compared with dicots, with 40% of monocots using the C 4 pathway, compared with only 4.5% of dicots. Despite this, only three families of monocots use C 4 carbon fixation compared to 15 dicot families.

The amount of organic matter by weight in organic soil is > 20%. Soils containing 12% to 18% SOC are generally classified as organic soils. Soil organic matter (SOM) is the organic matter component of soil, consisting of plant and animal detritus at various stages of decomposition, cells and tissues of soil microbes, and substances that soil microbes synthesize. Although these three elements make up about 92% of the dry weight of the organic matter in the soil, other elements are very important for the nutrition of plants, including nitrogen, phosphorus, potassium, sulfur, calcium, magnesium and many micronutrients.

Fertilizer use is profitable if each rupee spent on fertilizer produces a crop worth at least Rs. 2. A fertilizer is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Data on the fertilizer consumption per hectare of arable land in 2012 are published by The World Bank.

The planned geographical distribution of major genes for specific resistance to pathogens for use in varietal development and production is referred to as Gene deployment. Gene deployment is the guided distribution of genes in space and time. Gould divided the gene deployment strategies into two broad categories- 1) spatial (gene deployment at the farm level, at the field level, and the region level) and 2) temporal.

Stage-III of rust fungi is marked by Teliospores. Teliospores have been defined as the basidia-producing spores of rust fungi. The teliospores are important for the overwintering of most cereal rosts, and they are largely responsible for the formation of new physiologies races of the rosts. Rusts are plant diseases caused by pathogenic fungi of the order Pucciniales.

Root growth is particularly affected by P. Phosphorus is also associated with complex energy transformations in the plant. Adding phosphorus to soil low in available phosphorus promotes root growth and winter hardiness, stimulates tillering, and often hastens maturity.

In the rust cycle, the cereal host is infected by Aeciospores. Aeciospores are one of several different types of spores formed by Rusts. They each have two nuclei and are typically seen in chain-like formations in the aecium. Aeciospores are dispersal structures and heteroecious rusts need to land on the primary host.

In flowering plants, archesporium gives rise to Wall and tapetum. The cell or group of cells from which spore mother cells develop (as those from which the microspores develop in the pollen sac or the megaspore in the ovule). A two-lobed anther develops four pollen sacs that situate at four corners of the anther. Development of pollen sacs begins with the differentiation of archesporial cells in the hypodermal region below the epidermis at four corners of the young anther. The archesporial cells divide by periclinal division to give a subepidermal primary parietal layer and a primary sporogenous layer.

Yellow mosaic virus disease of moong, also known as mung bean yellow mosaic virus (MYMV), is primarily transmitted by the insect vector Bemisia tabaci . Bemisia tabaci, commonly known as the whitefly, is a notorious vector for various plant viruses, including yellow mosaic viruses. It feeds on the sap of infected plants and transmits the virus to healthy plants as it moves between them. B. Aphir crassivora: Aphir crassivora is not known to be a vector for the yellow mosaic virus disease of moong. It is not associated with the transmission of this particular virus. C. Nephotettix viruscens: Nephotettix viruscens is not known to be a vector for the yellow mosaic virus disease of moong. It is associated with the transmission of rice viruses, not the yellow mosaic virus of moong. D. None of these: This option is incorrect since the correct answer is A. Bemisia tabaci , which is known to spread the yellow mosaic virus disease of moong. Therefore, the correct answer is: A. Bemisia tabaci

The active compound in mineral gypsum and phosphogypsum is Calcium sulphate. Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ·2H 2 O. Phosphogypsum (PG) is the calcium sulfate hydrate formed as a by-product of the production of fertilizer from phosphate rock. It is mainly composed of gypsum. Although gypsum is a widely used material in the construction industry, phosphogypsum is usually not used but is stored indefinitely because of its weak radioactivity.

Sir Edwin John Butler is regarded as the father of Indian Phytopathology. Plant pathology or phytopathology is the scientific study of diseases in plants caused by pathogens and environmental conditions. He was an Irish mycologist and plant pathologist. He became the Imperial Mycologist in India and later the first director of the Imperial Bureau of Mycology in England. He has been called the Father of Mycology and Plant Pathology in India.

Tundu disease (yellow ear rot) of wheat caused by Clavibacter tritici is usually associated with Anguina tritici. The disease was first described by Hutchinson from Punjab in India. Milne (1919) observed the disease incidence depended on mechanical injury to the plant parts by eelworms and that the bacterium could grow only on the excretion of the eelworms. The 'tundu' disease is characterized by twisting of the stem, distortion of the earhead, and rooting of the spikelets with a profuse oozing liquid from the affected tissues. Hence, the name of the disease is yellow ear rot. The ooze contains masses of bacterial cells.

Lactic acid fermentation does not produce CO 2 and NADH. Lactic acid fermentation is a metabolic process by which glucose or other six-carbon sugars are converted into cellular energy and the metabolite lactate, which is the lactic acid in solution. It is an anaerobic fermentation reaction that occurs in some bacteria and animal cells, such as muscle cells.

The Downey mildew disease of pearl millet is primarily Soil borne. Downy mildew of pearl millet, it is referred to as 'green ear' is the most destructive disease of pearl millet. This disease is widely distributed in temperate and tropical areas of the world and is especially important in India. This fungus is soil-borne. The fungus may persist in the soil for five to ten years. Under cool, water-saturated soil conditions, the spores, upon contact with roots, germinate and enter the seedling's roots, and spread throughout the entire plant.

Ug 99 race specific to Puccinia graminis tritici. Ug 99 is a lineage of wheat stem rust ( Puccinia graminis f. sp. tritici ), which is present in wheat fields. It is predicted to spread rapidly through these regions and possibly further afield, potentially causing a wheat production disaster that would affect food security worldwide. Ug 99 and its variants differ from other strains of the Black Stem Rust pathogen due to their ability to overcome resistance genes in wheat that has been durable against the BSR pathogen for decades.

PR-9 has the property of Peroxidase. Pathogenesis-related (PR) proteins are proteins produced in plants in the event of a pathogen attack. They are induced as part of systemic acquired resistance. Pathogenesis-related proteins, often called PR proteins, are structurally diverse groups of plant proteins that are toxic to invading fungal pathogens. PR-9 is Haem peroxidase has Tobacco lignin forming peroxidase.

Needham described the first plant nematode disease, the seed gall caused by Anguina tritici in 1743 AD. Turbevil Needham (1743) accidentally recorded the first plant parasitic nematode when he crushed one of the shrunken and blackened wheat grains and observed "Aquatic worms, Eels, or Serpents, which they very much resemble. Anguina tritici is a plant pathogenic nematode. It was the first plant parasitic nematode to be described in the literature in 1743. It causes a disease in wheat and rye called "ear-cockle" or seed gall.