Plant Pathology MCQ Question and Answer | Agriculture MCQ Question

Control agent is not a component of the disease tetrahedron.
A disease pyramid or tetrahedron, allows for the addition of a fourth causal factor of disease. Humans factor into the disease triangle because the influence of human activity on disease is pervasive in agriculture.
The concept of a disease pyramid or tetrahedron is composed of four main components that are environment, pathogen, host and host microbiome. The control agent is not a component of this tetrahedron.

Loose smut of barley is internally seed-borne.
Loose smut of barley is caused by Ustilago nuda. It is a disease that can destroy a large proportion of a barley crop. Loose smut replaces grain heads with smut, or masses of spores that infect the open flowers of healthy plants and grow into the seed, without showing any symptoms.
Loose smut of barley and wheat are internally seed-borne and carried as a small colony of fungus inside the seed embryo rather than as spores on the seed coat.

Quick and accurate detection of viruses can be done by ELISA, HADAS and IEM.
The enzyme-linked immunosorbent assay (ELISA), whose sensitivity and practicability have rendered it the most common primary screening assay.
The most sensitive IEM technique in viral diagnosis is solid phase IEM (SPIEM). IEM mainly relies on high-affinity virus-specific antibodies or other specific ligands, e.g. lectins that may be used in different ways.

Premature leaf fall is caused due to the deficiency of nitrogen.
Premature leaf drop is prevalent in the landscape due to dry weather. Plants are drought damaged by leaf desiccation, slowing of photosynthesis, and slowing of growth. Leaves wilt or roll, turn off colour and drop.
Symptoms of nitrogen deficiencies in plants are general chlorosis of the leaves, which is when leaves turn pale green and leaves cup upwards quite severely in deficient plants.

The most widely used fungicide for rust fungi is Plantvax.
PLANTVAX 750 WP Fungicide systemically controls Rust in green beans, geraniums, roses, carnations, irises, chrysanthemums and snapdragons.
Plantvax is an effective protective fungicide due to its systemic action. It is a wettable powder fungicide to be used as a foliar spray for the control of rust diseases of ornamentals grown in enclosed commercial structures.

Super digested compost is called so because Super phosphate is added to the compost during its preparation.
Super digested Compost is an environmentally natural fertilizer, which is a mixture of decomposed organic matter and is used to improve soil structure and provide nutrients, it acts as a fertilizer and can also be used as a mulch to suppress weeds and retain moisture.
And on the addition of superphosphate fertilizer make it more nutritive and effective to be used.

The nutrients which affect growing tips most are Ca and B.
Calcium is an essential plant nutrient. It plays an extremely important role in producing plant tissues and it enables plants to grow better. Calcium is responsible for holding together the cell walls of plants.
B is one of the essential nutrients for the optimum growth, development, yield, and quality of crops. It performs many important functions in plants and is mainly involved in cell wall synthesis and structural integration.

The site for the light reaction is Grana.
The light reaction takes place in Grana i.e. in the discs of the thylakoid. There, water (H₂O) is oxidized and oxygen (O₂) is released.
The electrons freed up from water are transferred to ATP and NADPH. The dark reaction occurs outside of the thylakoids.

The element responsible for maintaining turgor is K.
"Potassium's biggest role is to maintain turgor pressure by regulating osmotic pressure in the plant, by moving water around."
Turgor pressure is the hydrostatic pressure over ambient atmospheric pressure which can build up in living, walled cells. Turgor is generated through the osmotically driven inflow of water into cells across a selectively permeable membrane; this membrane is typically the plasma membrane.

The yellow vein mosaic of Abelmoschus esculanta (okra) is spread by Bemisia tabaci.
Yellow vein mosaic disease (YVMD) is a major biotic constraint on okra (Abelmoschus esculentus) cultivation in Sri Lanka. Diseased plants show characteristic symptoms of mosaic and vein yellowing on leaves and small and yellowish-green fruits.
The virus is transmitted by whitefly (Bemisia tabaci Genn.), which is the most severe pest of many crops in the world. The virus is responsible for 80–90% of yield losses and it affects all the developmental stages of okra plants.