Plant Pathology - Study Mode

[#496] High CO 2 concentration in leaf interior will cause
Correct Answer

(B) Stomatal closure

Explanation

Solution: High CO 2 concentration in the leaf interior will cause Stomatal closure. Higher than ambient CO 2 concentrations mediate a closure of stomatal pores in plants and conversely, low CO 2 concentrations trigger the opening of stomatal pores. Stomatal opening is induced by low CO 2 concentrations, high light intensity and high humidity. By contrast, closing is promoted by high CO 2 concentrations, darkness, drought and the plant hormone ABA.

[#497] Select the disease(s) caused by Mycoplasma like organisms (MLO)
Correct Answer

(D) All of these

Explanation

Solution: 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.

[#498] In endosperms of Maize and Pinus the ploidy levels are
Correct Answer

(B) Triploid and haploid

Explanation

Solution: 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.

[#499] Out of 38 ATP molecules produced per glucose, 32 ATP molecules are molecules are formed from NADH/FADH 2 in
Correct Answer

(A) Respiratory chain

Explanation

Solution: Out of 38 ATP molecules produced per glucose, 32 ATP molecules are formed from NADH/FADH 2 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.

[#500] The number of ATP molecules produced by electron transport system from Krebs cycle intermediates in a single turn is
Correct Answer

(B) 12

Explanation

Solution: 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 NADH 2 is oxidized and 2 molecules of ATP are synthesized when one molecule of FADH 2 is oxidized. Thus the total ATP produced on oxidation of reduced coenzymes produced in one turn of the Krebs cycle are (3 × 3 NADH 2 ) + (2 × 1 FADH 2 ) + 1 ATP = 12 ATP molecules.