Cellular Respiration and Enzymes

Succinate was placed in one of the most important cyclic pathways in metabolism, a collecting pool of catabolic and a starting point of many anabolic processes. Succinate is a product of substrate-level phosphorylation materialized in the citric acid cycle. It is involved in a macrophage-specific metabolic pathway generating and is also a downstream product of the α-ketoglutarate dehydrogenase complex, a heavily regulated multi-subunit complex.

• The Burning of glucose during respiration requires oxygen. When a Muscle is subjected to continuous exercise there will be low availability of oxygen. This leads to the anaerobic breakdown of glucose which results in the formation of lactic acid. 
• This accumulation of lactic acid in the muscle causes muscle fatigue.
• Hence Muscles get fatigued due to the accumulation of lactic acid.
• So, the correct answer is 'Lactic acid'.

• Generally, the glucose undergoes metabolism in the presence of oxygen to form ATP (Adenosine triphosphate) which is essential for the muscle contraction but during strenuous exercise, the body cannot meet the oxygen demand and the glucose undergoes metabolism in the absence of oxygen which results in the formation and accumulation of lactic acid.
  
• This accumulated lactic acid is moved to the liver and converted into glycogen thorough Cori cycle.
• Cori cycle takes place in the liver.
• Hence In the anaerobic reaction of muscle, lactic acid is produced which causes painful tiredness. The lactic acid accumulated is catabolized by the mechanism of the Cori cycle in the liver.
• So, the correct answer is 'In liver by Cori cycle'

• Generally, the glucose undergoes metabolism in the presence of oxygen to form ATP(adenosine triphosphate) which is essential for the muscle contraction but during vigorous exercise, the body cannot meet the oxygen demand and the glucose undergoes metabolism in the absence of oxygen which results in the formation and accumulation of lactic acid.
  
• This Lactic acid generated during muscle contraction is elaborated to form glycogen in Liver through Cori cycle.
  
• So, the correct answer is 'Liver'.

The body prefers to generate most of its energy using aerobic methods. During physical exercise such as lifting heavy weights, energy production is faster than our bodies can adequately deliver oxygen. In those cases, the working muscles generate energy anaerobically. This energy comes from glucose through a process called glycolysis, in which glucose is broken down or metabolized into a substance called pyruvate. When the body has plenty of oxygen, pyruvate is shuttled to aerobic pathway to be further broken down for more energy. But when oxygen is limited, the body temporarily converts pyruvate into a substance called lactate and accumulates in the muscle. 

• When you exercise, your muscles move more vigorously than when you are at rest. Their metabolic rate increases. 
• They need more energy, so they produce more of the chemical energy molecule ATP. 
• Your muscles begin converting glucose into lactic acid instead of energy when anaerobic exercise takes over, power output drops and fatigue sets in. Hence, when Muscles run out of oxygen muscles begin converting glucose into lactic acid.

Heavy metals like mercury (Hg2+) act as non-competitive or irreversible inhibitors by binding to the sulfhydryl groups of enzymes, thereby denaturing them or blocking their active sites.

The Cori cycle (also known as lactic acid cycle), refers to the metabolic pathway, in which lactate produced by anaerobic glycolysis in the muscles moves to the liver and is converted to glucose, which then returns to the muscles and is metabolised back to lactate.

Ethylene is a metabolic product of methionine. It is synthesized from methionine amino acid by methionine cycle or yang cycle. Methionine is first converted to adenosylmethionine. It is then converted to Aminocyclopropane carboxylic acid. It is then oxidized to form ethylene. It is a gaseous plant hormone which stimulates ripening of fruits in plants.

Pyruvate oxidation, the Krebs cycle, and the electron transport chain occur in the mitochondria to produce ATP, CO2, and water.

The process of glycolysis yields 2 net ATPs and 2 NADH molecules. NADH is converted into ATP in mitochondrial electron transport chain if oxygen is present. In anaerobic respiration, there is no oxygen available so NADH does not lead to the formation of ATP molecules. Without oxygen, NADH builds up and the cell can run out of NAD. Without NAD glycolysis stops. To regenerate NAD, cells with anaerobic respiration carry out the process of fermentation in which NADH gets converted into NAD to restart glycolysis. 

The HMP pathway or pentose phosphate pathway that produces 5 carbon compound and NADPH in the form of energy. Additionally, these pathways can operate in the anabolic direction to transform glycolytic intermediates into other compounds. So, HMP pathway is a  direct oxidation pathway performed without glycolysis cycle. HMP shunt produces some glycolytic intermediated like glyceraldehyde-3-phosphate and fructose-6-phosphate that can directly involve in the glycolysis pathway or EMP. Thus, the correct answer is option A.

Hydrolysis of complex organic compounds (like in anaerobic digestion) typically occurs under anaerobic conditions, where oxygen is absent.