Plant Pathology MCQ Question and Answer | Agriculture MCQ Question

High CO₂ concentration in the leaf interior will cause Stomatal closure.
Higher than ambient CO₂ concentrations mediate a closure of stomatal pores in plants and conversely, low CO₂ concentrations trigger the opening of stomatal pores.
Stomatal opening is induced by low CO₂ concentrations, high light intensity and high humidity. By contrast, closing is promoted by high CO₂ concentrations, darkness, drought and the plant hormone ABA.

The diseases caused by Mycoplasma-like organisms (MLO) are Brinjal little leaf, Rice yellow dwarf, and Sugarcane grassy shoot.
Mycoplasma is a genus of bacteria that, like the other members of the class Mollicutes, lack a cell wall around their cell membranes.
This characteristic makes them naturally resistant to antibiotics that target cell wall synthesis. They can be parasitic or saprotrophic and causes different diseases in plants as well as humans.

In endosperms of Maize and Pinus the ploidy levels are Triploid and haploid.
The embryo cells are diploid and made of one paternal and one maternal haploid genome, whereas the endosperm is constituted of triploid cells made of two maternal haploid genomes and one paternal haploid genome.
In gymnosperms like pinus, there is no double fertilization and the endosperm is formed before fertilization. The haploid megaspore undergoes repeated divisions and forms a haploid endosperm.

Out of 38 ATP molecules produced per glucose, 32 ATP molecules are formed from NADH/FADH₂ in the Respiratory chain.
NADH is the electron donor in this system. It initiates the electron transport chain by donating electrons to NADH dehydrogenase.
NADH is oxidized to NAD in this process. Complex II oxidizes FADH, garnering still more electrons for the chain. At complex III, no additional electrons enter the chain, but electrons from complexes I and II flow through it. When electrons arrive at complex IV, they are transferred to a molecule of oxygen.

The number of ATP molecules produced by the electron transport system from Krebs cycle intermediates in a single turn is 12.
The tricarboxylic acid (TCA) cycle, also known as the Krebs or citric acid cycle, is the main source of energy for cells and an important part of aerobic respiration.
The cycle harnesses the available chemical energy of acetyl coenzyme A (acetyl CoA) into the reducing power of nicotinamide adenine dinucleotide (NADH).
3 molecules of ATP are synthesized when one molecule of NADH₂ is oxidized and 2 molecules of ATP are synthesized when one molecule of FADH₂ is oxidized. Thus the total ATP produced on oxidation of reduced coenzymes produced in one turn of the Krebs cycle are (3 × 3 NADH₂) + (2 × 1 FADH₂) + 1 ATP = 12 ATP molecules.

Puccinia path in India is given by Nagarajan & Joshi.
The defined dispersal route from South to North is called the "Puccinia Path" of India. Unlike North America, the spread from the Nilgiris to central India is an independent event and there is no feedback of inoculum to the Nilgiris.
Long distance spread of the airborne wheat stem rust uredospores depends on upper-air weather patterns. Trajectories of the airborne inoculum at the 700 mb level led fro the nilgiris, the southern area to the secondary foci of infection.

Leaf spot or tikka disease of groundnut is/are caused by Cercospora arachidicola and Cercosporidium personatum.
Peanut leaf spots are caused by two different fungi: Nothopassalora personata (previously known as Cercosporidium personatum) causes late leaf spots and Passalora arachidicola (previously known as Cercospora arachidicola) causes early leaf spots.
It is one of the most detrimental foliar diseases of groundnut. This disease, due to its drastic reduction of photosynthetic tissues in plant foliar parts, leads to about 70% yield loss in susceptible cultivars.

Bacterial diseases are controlled by the use of chemicals called Antibiotics.
An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of such infections.
They may either kill or inhibit the growth of bacteria. A limited number of antibiotics also possess antiprotozoal activity.

Concentration of agar in the pour plate technique is 1.5%.
Agar is typically used in a final concentration of 1 - 2% for solidifying culture media. Smaller quantities (0.05 - 0.5%) are used in media for motility studies and the growth of anaerobes (0.1%) and microaerophiles.
In these media, the agar which is an unbranched long chain of polysaccharides is added in the concentration of 1.5. Most commonly, 1.3% agar is used to prepare solid media in labs.

CAM occurs in Fleshy green leaves.
Crassulacean acid metabolism (CAM) is a photosynthetic adaptation to periodic water supply, occurring in plants in arid regions (e.g., cacti) or in tropical epiphytes (e.g., orchids and bromeliads).
CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions that allows a plant to photosynthesize during the day, but only exchange gases at night.