The process by which the glucose (6C compound) is split into two molecules of pyruvic acid (3C compound) is called glycolysis or EMP pathway. It occurs in the cytoplasm. In glycolysis, 4ATP and 2NADH$ _2$ molecules are formed and 2ATP molecules are consumed in hexose phase

The mechanism of respiration is initiated by breaking down glucose to pyruvic acid without the help of oxygen. The initial process occurs in the cytosol of cells which requires glucose as well as ATP molecules which provide energy for the process to start. This initial process is known as glycolysis and it takes place in 10 steps in which total 4 ATP molecules are produced and 2 ATP molecules are consumed. Thus, these are the net production of 2 ATP molecules. 

 1 NADH = 3 ATP, 1 FADH = 2 ATP

During the conversion of fructose-1,6-bis-phosphate to lactate, the pathway generates a total of four molecules of ATP, resulting in a net yield of two ATP per glucose consumed.

Peter Dennis Mitchell was a British biochemist, who was awarded the 1978 Nobel prize for chemistry for his discovery of the 'chemiosmotic mechanism' of ATP synthesis.
Pentose phosphate pathway was discovered by Warburg and Dickens. It is a pathway of hexose oxidation in which glucose-6-phosphate undergoes two successive oxidations by NADP, the final one being oxidative decarboxylation to form a pentose phosphate.
EMP pathway is known as 'Embden-Meyerhof-Parnas pathway'. It is also called as glycolysis. It converts glucose to pyruvate.
Kostychev was first Russian scientist to explain anaerobic respiration. He applied his knowledge of microbiology to the study of the decomposition of organic matter in the soil. Thus, the correct answer is option C.

The pentose phosphate pathway also called the hexose monophosphate shunt, is a shunt from glycolysis designed to produce either NADPH or ribose or both. There are two distinct phases in the pathway. The first is the oxidative phase, in which NADPH is generated, and the second is the non-oxidative synthesis of 5-carbon sugars. In the pentose phosphate pathway, glucose 6-phosphate is directly oxidized without entering glycolysis. Even Kreb's cycle and oxidative phosphorylation doesn't happen in pentose phosphate pathway.

Pentose phosphate pathway is also called as phosphogluconate pathway or Hexose Monophosphate Shunt (HMP Shunt). It occurs in most organisms in cytoplasm. It results in generation of NADPH, ribose-5-phosphate (R5P) and erythrose 4-phosphate (E4P). R5P is precursor for the synthesis of nucleotides. E4P is involved in the synthesis of aromatic amino acids. 

In the oxidation of one glucose molecule, during aerobic respiration, 2NADH₂ in link reaction, 2NADH₂ in glycolysis, 8NADH₂ in Krebs cycle are formed.

So, the correct option is ‘A=1, B=1, C=4 or A=2, B=2, C=8’.

• For the aerobic respiration the substrate glucose has  to undergo a following set of process 
• First of which is glycolysis where the molecule of glucose is broken down to 2 molecules of pyruvate.
• These pyruvate molecules are to be cconverted to Acetyl CoA so that it can enter the mitochondrial membrane and undergo kerb cycle.
• After being converted to acetyl coA it takes part in kerb cycle where molecules of NADH, FADH and ATP are formed.
• These NADH, FADH molecules are the electron acceptors which are used in ETS to transport electron and hydrogen ions through the complexs.
• These electrons and hydrogen ions are used for the formation of ATP via ATP synthase.
• Therefore the process for the aerobic breakdown of glucose is Glycolysis followed by transition of pyruvate then citric acid cycle which is followed by electron transport system.
• Therefore the correct answer is 'Glycolysis-transition-citric acid cycle-electron transport system'

Under Anaerobic conditions, Pyruvic Acid enters in matrix of mitochondrion and undergoes oxidative decarboxylation to form 2 carbon energy rich compound called Acetyl Co A.

This process utilizes 2 oxygen atoms. Incomplete oxidation of Pyruvate leads to the formation of lactic acid in muscles and formation of ethyl alcohol in yeast as a process of fermentation.

So, the correct answer is '2'

Opioids are a type of drug. They are also referred to as narcotics. In the human body, the opioid receptors are present at a variety of locations, including the brain, in the spinal cord, on peripheral neurons, and the digestive tract. They often act as pain relievers.

Glycolysis is a series of reactions that extract energy from glucose by splitting it into two three-carbon molecules called pyruvates. Glycolysis takes place in the cytosol of a cell, and it can be broken down into two main phases: the energy-requiring phase and  the energy-releasing phase. Each three-carbon sugar is converted into another three-carbon molecule, pyruvate, through a series of reactions. In these reactions, ATP molecules and one NADH molecule are made. Because this phase takes place twice, once for each of the two three-carbon sugars, it makes four ATP and two NADH overall.

2 molecules of ATP is utilized during the conversion of glucose into fructose 1,6 diphosphate.

Substrate-level phosphorylation is the direct transfer of phosphate group to ADP to form ATP. It accounts of 100% of the ATP formed by the reactions of glycolysis. The first substrate-level phosphorylation occurs when 1, 3 - diphosphoglyceraldehyde is converted to 1, 3 - diphosphoglyceric acid and 2 NADH$ _2$ are formed, that is 6 ATP are formed. The 1, 3-diphosphoglyceric acid is then dephosphorylated to 3 phosphoglyceric acid producing 2 ATP via substrate-level phosphorylation. The second substrate-level phosphorylation occurs when phosphoenolpyruvic acid is converted to pyruvic acid producing 2 ATP molecules.

• The thyroid gland is composed of two lobes that are located on either side of the trachea.
• Follicular cells of the thyroid gland synthesize two hormones, tetraiodothyronine or thyroxine ($T _4$) and triiodothyronine ($T _3$). 
• Thyroid hormones play an important role in the regulation of the basal metabolic rate. 
• Hence the hormone secreted by the thyroid gland is thyroxine.
• So, the correct answer is 'Thyroxine'.