Plant Pathology MCQ Question and Answer | Agriculture MCQ Question

Cohesion-tension theory of Dixon and Jolly explains the ascent of sap.
The ascent of sap in the xylem tissue of plants is the upward movement of water and minerals from the root to the aerial parts of the plant.
The work was published by Dixon in book form with a great wealth of experimental details in 1914. The theory states that transpiration pull or tension, cohesion property of water, and hydration of the cell walls are collectively responsible for the ascent of sap.

Algae is the source of Agar Agar.
Agar or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae.
Agar was first subjected to chemical analysis in 1859 by the French chemist Anselme Payen, who had obtained agar from the marine algae Gelidium corneum.
It forms the supporting structure in the cell walls of certain species of algae and is released on boiling. These algae are known as agarophytes, belonging to the Rhodophyta (red algae) phylum.

The rate of water absorption is slow near the freezing point because Cell membranes become more viscous.
Membrane fluidity refers to the viscosity of the lipid bilayer of a cell membrane or a synthetic lipid membrane.
As the temperature lowers, the water or moisture in the atmosphere starts freezing that ultimately lowering the rate of absorption.

Steamed bone meal contains 30 - 35% P₂O₅.
Bone meal is a mixture of finely and coarsely ground animal bones and slaughter-house waste products. It is used as a dietary supplement to supply calcium (Ca) and phosphorus (P) to monogastric livestock in the form of a hydroxiapathite.
The N-P-K rating of bone meal is typically 3-15-0 along with a calcium content of around 12% (18% CaO equiv.) and 30 - 35% P₂O₅.
It is used as an organic fertilizer for plants and as a nutritional supplement for animals. As a slow-release fertilizer, bone meal is primarily used as a source of phosphorus and protein.

The C : N ratio of farmyard manure is 40 : 1.
C : N ratio is the ratio of the mass of carbon to the mass of nitrogen in a substance.
FYM (Farmyard manure) is an important organic resource for agricultural production in live-stock-based farming systems in the semi-arid tropics of India.
The C : N ratio of farmyard manure is 40 : 1.

In hexose monophosphate shunt, number of molecules of carbon dioxide evolved is more than in glycolysis.
Hexose monophosphate shunt and the HMP Shunt) is a metabolic pathway parallel to glycolysis. It generates NADPH and pentoses (5-carbon sugars) as well as ribose 5-phosphate, a precursor for the synthesis of nucleotides.
In HMP, 6 carbon dioxide molecules are produced whereas in glycolysis no CO₂ molecule is produced.

Light energy is converted into chemical energy in the presence of Chloroplasts.
The phenomenon involved in conversion of light energy I to chemical energy in the chloroplasts is termed Photosynthesis.
In plants and algae, photosynthesis takes place in organelles called chloroplasts. A typical plant cell contains about 10 to 100 chloroplasts.

Pyrimidines, Triazoles and Metalaxyl are the systemic fungicides.
A Systemic fungicide may be defined as a fungicidal compound that is readily translocated as such in the plant, rendering the tissues penetrated toxic to fungi.
New pyrimidine derivatives were synthesized and their antifungal activities were evaluated in vitro against fourteen phytopathogenic fungi.
Triazole fungicides (TFs) are systemic pesticides, which are widely used to prevent fungal diseases in agriculture, thereby protecting vegetables, fruits and crops.
Metalaxyl is a systemic fungicide used to control plant diseases caused by Oomycete fungi. Its formulations include granules, wettable powders, dust, and emulsifiable concentrates.

Potassium is the nutrient element is responsible for resistance to plant disease.
Potassium is associated with the movement of water, nutrients and carbohydrates in plant tissue. It's involved with enzyme activation within the plant, which affects protein, starch and adenosine triphosphate (ATP) production. The production of ATP can regulate the rate of photosynthesis.
Natural disease resistance mechanisms can be enhanced by plant nutrients like potassium.

Potato virus diseases are spread by Aphids.
Aphids are sap-sucking insects and have piercing, sucking mouthparts. Their mouthparts include a needle-like stylet that allows the aphid to access and feed on the contents of plant cells.
Potato virus is spread naturally in a non-persistent manner by many aphid species and can be mechanically transmitted. The virus is transmitted when an aphid initially probes the plants.
The most important viruses transmitted by aphids to potatoes in Scotland are potato leaf roll virus (PLRV), potato virus Y (PVYO and PVYN (veinal necrosis)) and potato virus A (PVA).