Plant Pathology MCQ Question and Answer | Agriculture MCQ Question

The largest group of the virus is Closteroviridae.
Closteroviridae is a family of viruses. Plants serve as natural hosts. Viruses in the family Closteroviridae are non-enveloped, with flexuous and filamentous geometries.
The diameter is around 10 - 13 nm, with a length of 950 - 2200 nm. Genomes are linear and non-segmented, bipartite, and around 20kb in length.
The family Closteroviridae contains more than 30 plant viruses with flexuous, filamentous virions, with either mono- or bipartite (one tripartite) single-stranded positive-sense RNA genomes.

Complete girdling ultimately kills the tree due to Starvation of roots.
Girdling also called ring-barking, is the complete removal of the bark from around the entire circumference of either a branch or trunk of a woody plant. Girdling results in the death of the area above the girdle over time.
Girdling results in the removal of the phloem, and death occurs from the inability of the leaves to transport sugars to the roots. In this process, the xylem is left untouched, and the tree can usually still temporarily transport water and minerals from the roots to the leaves.

In aerobic respiration one glucose produces 10 NADH + 2 FADH₂ + 2 ATP + 2 GTP.
Aerobic respiration requires oxygen (O₂) to create ATP. The potential of NADH and FADH₂ is converted to more ATP through an electron transport chain with oxygen and protons as the "terminal electron acceptors".
In aerobic conditions, the process converts one molecule of glucose into two molecules of pyruvate (pyruvic acid), generating energy in the form of two net molecules of ATP.

In plants, nitrate is reduced to an ammonia state in two steps. In the second step, electrons are donated by Ferredoxin.
First, nitrate is reduced to nitrite in the cytoplasm by nitrate reductase and then nitrite is reduced to ammonia by nitrite reductase in the chloroplasts.
In chloroplasts, Fe₂S₂ ferredoxins function as electron carriers in the photosynthetic electron transport chain and as electron donors to various cellular proteins, such as glutamate synthase, nitrite reductase, sulphite reductase, and the cyclase of chlorophyll biosynthesis.

Uredospores produced in Nilgiri and Palney hills during the off-season of the crop are the primary source of inoculum for stem rust of water for southern and central India.
Uredospore is one of the thin-walled spores that are produced by uredinial hyphae and spread the fungus vegetatively. Since the urediniospores are produced on the cereal host and can infect the cereal host, the infection can pass from one year's crop to the next without infecting the alternate host.
In other cases the fungus passes between winter wheat and spring wheat, meaning that it has a cereal host all year round. Since the urediniospores are wind dispersed, this can occur over large distances.

The Bordeaux mixture was first time used for the control of Downey mildew of grape vines. Bordeaux mixture is a mixture of copper(II) sulphate (CuSO₄) and quicklime (CaO) used as a fungicide.
It is used in vineyards, fruit farms and gardens to prevent infestations of downy mildew, powdery mildew and other fungi.
It is sprayed on plants as a preventive treatment, but its mode of action is ineffective after a fungus has become established.

Causal organism of smut of bajra is Tolyposporium penicillariae.
Tolyposporium penicillariae, the causal agent of pearl millet smut. Sporeballs of Tolyposporium penicillariae varied from circular to near-polyhedral and measured 42-325 × 50-175 μm.
The number of teliospores aggregated in balls varied from 200 to 1400. Teliospores were mostly circular and measured 7-12 μm diam.

PS II performs Photolysis of water.
Photosystem II is the first protein complex in the light-dependent reactions of oxygenic photosynthesis. It is located in the thylakoid membrane of plants, algae and cyanobacteria.
The energized electrons are replaced by oxidizing water to form hydrogen ions and molecular oxygen. By replenishing lost electrons with electrons from the splitting of water, photosystem II provides the electrons for all of the photosynthesis to occur.

The rate of transpiration is related to Light, temperature, atmospheric humidity and wind.
Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers.
The rate of transpiration is controlled by the stomatal aperture, and these small pores open especially for photosynthesis, a light supply will encourage open stomata.
Temperature affects the rate of transpiration in two ways, an increased rate of evaporation due to a temperature rise will hasten the loss of water.
Relative humidity affects drier surroundings giving a steeper water potential gradient, and so increasing the rate of transpiration.
In still air, water lost due to transpiration can accumulate in the form of vapour close to the leaf surface. This will reduce the rate of water loss, as the water potential gradient from inside to outside of the leaf is then slightly less.

Phenyl mercuric acetate Reduces transpiration.
Phenyl mercuric acetate (PMA) induced stomatal closure and decreased transpiration.
Stomata of leaves treated with any of the 3 PMA concentrations closed earlier and at a higher relative water content than did stomata of untreated leaves.