Plant Pathology MCQ Question and Answer | Agriculture MCQ Question

In bacteria, variability is caused by Conjugation, Transformation and Transduction.
Genetic exchanges among bacteria occur by several mechanisms.
In conjugation, the donor bacterium transfers DNA to the recipient by mating.
In transformation, the recipient bacterium takes up extracellular donor DNA.
In transduction, donor DNA packaged in a bacteriophage infects the recipient bacterium.

The correct sequence in electron acceptors in ATP synthesis is Cyt b, c, a, a₃.
Cytochromes are proteins that contain heme as their prosthetic group and whose principal biological function, in the cells of animals, plants, and microorganisms, is electron transport.
The mobile cytochrome electron carrier in mitochondria is cytochrome c. The sequence of the movement of the electrons includes cytochromes b, cytochrome c, cytochrome a and cytochrome a₃.

Mass flow hypothesis was put forward by Munch.
Theory to explain the movement of sap through the phloem. It was proposed by Ernst Munch, a German plant physiologist in 1930.
A high concentration of organic substances, particularly sugar, inside cells of the phloem at a source, such as a leaf, creates a diffusion gradient that draws water into the cells from the adjacent xylem.

Smut includes in Basidiomycotina.
Basidiomycota is a group of fungi that includes mushrooms, bracket fungi, smuts, and rusts. These fungi are more prevalent in humid conditions.
The smuts are multicellular fungi characterized by their large numbers of teliospores. The smuts get their name from a Germanic word for dirt because of their dark, thick-walled, and dust-like teliospores.
The smuts are grouped with the other basidiomycetes because of their commonalities concerning sexual reproduction.

Fertilization is synonym with Syngamy.
Fertilization also known as generative fertilization, syngamy, and impregnation is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development.
Processes such as insemination or pollination which happen before the fusion of gametes are also sometimes informally called fertilization.

TMV plant virus was observed 1^st under electron microscope.
Tobacco mosaic virus (TMV) is a positive-sense single-stranded RNA virus species in the genus. The infection causes characteristic patterns, such as "mosaic"-like mottling and discoloration on the leaves.
TMV was the first virus to be discovered. It is the first pathogen identified as a virus. The virus was crystallized by W. M. Stanley. It has a similar size to the largest synthetic molecule, known as PG5.

Xylaria polymorpha is known as Dead man's finger.
Xylaria polymorpha, commonly known as dead man's fingers, is a saprobic fungus.
It is a common inhabitant of forest and woodland areas, usually growing from the bases of rotting or injured tree stumps and decaying wood.
It has also been known to colonize substrates like woody legume pods, petioles and herbaceous stems.

Tabtoxin is a Pathotoxin.
A chemical of biological origin, other than an enzyme, that plays an important causal role in a plant disease is known as Pathotoxin.
Tabtoxin, also known as wildfire toxin, is a simple monobactam phytotoxin produced by Pseudomonas syringae. It is the precursor to the antibiotic tabtoxinine β-lactam (TBL).
Tabtoxin is a dipeptide precursor to the biologically active form of TBL, differing by having an extra threonine attached by a peptide bond to the C terminus. Tabtoxin is required by BR2(R) for both chlorosis and lesion formation on the bean.

Wooden doors swell up and get stuck during the rainy season due to Imbibition.
Imbibition is a special type of diffusion that takes place when liquid is absorbed by solids-colloids causing an increase in volume.
Water surface potential movement takes place along a concentration gradient; some dry materials absorb water. A gradient between the absorbent and the liquid is essential for imbibition.
Dry wooden doors imbibe water from the moisture in the atmosphere during the rainy season and swell up.

The disease damping off seedlings during the nursery stage is caused by the pathogens Pythium aphanidermatum and Pythium debaryanum.
Damping off is a horticultural disease or condition, caused by several different pathogens that kill or weaken seeds or seedlings before or after they germinate. It is most prevalent in wet and cool conditions.
Damping off is caused by several soil-borne fungi and fungus-like organisms including Pythium, Phytophthora, Rhizoctonia, and Fusarium, which infect seedlings and cause them to 'damp off' or collapse and decay.