Respiration in Plants Test - 85

Phosphorylation is the process of ATP generation in cells. Oxidative phosphorylation occurs in mitochondria. Some of the important chemicals that interfere with oxidative phosphorylation are cyanide, carbon monoxide, azides - Inhibition of electron transfer; inhibit cytochrome oxidase.
Oligomycin inhibits F$$_{0}$$ and CF$$_{0}$$ components of ATP synthase.
Dinitrophenol- Uncoupling of phosphorylation and electron transfer.
Iodoacetate reacts reversibly with the free -SH groups of cysteine residues in proteins.

During glycolysis, the breakdown of the six-carbon glucose into two molecules of the three-carbon pyruvate occurs in ten steps, the first five of which constitute the preparatory phase. The energy gain comes in the second or payoff phase of glycolysis. In the preparatory phase of glycolysis, two molecules of ATP are invested and the hexose chain is cleaved into two triose phosphates. In the first step of glycolysis, glucose is activated for subsequent reactions by its phosphorylation at C-6 to yield glucose 6-phosphate, with ATP as the phosphoryl donor: This reaction, which is irreversible under intracellular conditions, is catalyzed by the enzyme hexokinase. The glucose molecule which is otherwise a stable molecule needs to be destabilised by addition of high energy phosphates in order to kick start its degradation and this purpose is served by hexokinase and later on phosphofructokinase enzyme in a subsequent reaction. The activated glucose Glucose 6 Phosphate is called active glucose. More the energy content in any molecule lesser will be its stability.

The inner membrane of mitochondria consists of many trans membrane proteins that are embedded within the inner membrane. These proteins shuttle electrons which are used to pump protons between space of outer and inner membrane. The proton gradient thus created help in production of ATP.

• Respiration is the process of the formation of energy in the form of ATP by the oxidation of an organic molecule. 
• The most common substrate used for respiration is glucose (a carbohydrate). 

Louis Pasteur was the first to describe the large (greater than tenfold) increase in glucose consumption by yeast culture, when it was shifted from aerobic to anaerobic conditions. This phenomenon, called the Pasteur effect, occurs without a significant change in the concentration of ATP or any of the hundreds of metabolic intermediates and products derived from glucose.

Krebs cycle leads to the production of α-Ketoglutarate as key intermediate after isocitrate and before succinyl-CoA. α-Ketoglutarate is one of the most important nitrogen transporters in metabolic pathways. The amino groups of amino acids are attached to it (by transamination) to transport it to the liver for ornithine cycle. So, the correct answer is option D.

If one mole of ATP is equal to 12 Kcal, then total 686 Kcal of energy will produce total of 57 ATP molecules which can be calculated by dividing 686 by 12. 

 In aerobic respiration, pyruvate formed at the end of glycolysis enters the TCA cycle and is completely oxidized to produce carbon dioxide, water, and energy in the form of ATP. In anaerobic alcoholic fermentation which is seen in yeast, glucose (sugar) is broken down into pyruvic acid which is then converted to ethanol due to lack of oxygen (anaerobic conditions). Therefore, the correct answer is option A.

Aldolase also known as fructose - bisphosphate aldolase B plays a key role in both glycolysis and gluconeogenesis. The fructose 1, 6- bisphosphate aldolase enzyme catalyzes the reversible cleavage of fructose 1, 6-bisphosphate into glyceraldehyde 3-phosphate and dihydroxyacetone phosphate (DHAP).