Test: Introduction to Respiration, Glycolysis & Fermentation - NEET MCQ

During respiration, the molecule utilized is oxygen, and the molecules released are carbon dioxide, water, and energy.

• Respiration is the process by which organisms extract energy from organic substances, such as glucose, in the presence of oxygen. 
• In the process of respiration, glucose is partially oxidized in several steps, releasing energy. Oxygen is consumed during the process, and carbon dioxide and water are produced as byproducts.
• The released energy is utilized by the cell for various metabolic activities, such as ATP synthesis, which is the primary energy currency of cells.

Option a) "Utilized: Oxygen; Released: Carbon dioxide, water, and energy" is the correct answer because it accurately describes the molecules involved in respiration and their respective roles.

In anaerobic respiration, glucose breaks down without oxygen. 
The chemical reaction transfers energy from glucose to the cell.
Anaerobic respiration produces lactic acid(C₃H₆O₃), rather than carbon dioxide and water. CH₃COCOOH is pyruvic acid, C₂H₅OH is ethyl alcohol and CH₃COOH is acetic acid.

Hence, option D is correct.

Glycolysis is common to both aerobic respiration and anaerobic respiration.

In the first step, each glucose molecule (6 carbon molecules) is broken down into two molecules of pyruvate (3 carbon molecules) by the process of glycolysis. 
The process occurs in the cytoplasm of the cell and does not require the presence of oxygen. 

Glycolysis is the first stage of the breakdown of glucose in the cell. 

During glycolysis 2 ATP molecules are used up and four ATP molecules are generated. In the entire process of glycolysis, two NADH₂ molecules are also generated. When these molecules undergo ETS they will form 3 ATP per NADH₂  which means 6 ATP.

Therefore the total ATP that are forming are 10 and as 2 ATP is used up the net gain will be 8.

So, the correct option is '8'

Glycolysis takes place in the cytoplasm of a cell as the first step in cellular respiration of the Kreb’s cycle. When glycolysis occurs, it breaks down glucose into pyruvic acids in the cytoplasm.

The initial step in glycolysis is the conversion of glucose to glucose-6-phosphate. This process is catalyzed by the enzyme hexokinase. In this step, a phosphate group is added to glucose, forming glucose-6-phosphate.

This phosphorylation of glucose is an important regulatory step in glycolysis and helps to trap glucose within the cell, preventing it from freely diffusing out.

The enzyme that converts sucrose into glucose and fructose is invertase. Invertase is a type of glycosidase enzyme that catalyzes the hydrolysis of sucrose, which is a disaccharide composed of glucose and fructose. By breaking the bond between glucose and fructose, invertase allows for the separation of these two monosaccharides.

Option a) "Invertase" is the correct answer because it correctly identifies the enzyme responsible for the conversion of sucrose into glucose and fructose.

The step of glycolysis that involves the formation of NADH + H⁺ is the conversion of 3-phosphoglyceraldehyde to 1, 3-bisphosphoglycerate. During this step, the enzyme glyceraldehyde-3-phosphate dehydrogenase catalyzes the oxidation of glyceraldehyde-3-phosphate (3-phosphoglyceraldehyde) and the transfer of electrons to the coenzyme NAD⁺ (nicotinamide adenine dinucleotide), resulting in the formation of NADH + H⁺.

Option c) "Conversion of 3-phosphoglyceraldehyde to 1, 3-bisphosphoglycerate" is the correct answer because it correctly identifies the step in glycolysis where NADH + H⁺ is formed by the oxidation of 3-phosphoglyceraldehyde.

1. Decarboxylase and dehydrogenase

Explanation: In yeast fermentation, the conversion of pyruvic acid to ethanol occurs in two steps:

1. Pyruvic acid decarboxylase catalyzes the conversion of pyruvic acid to acetaldehyde by removing carbon dioxide.
2. Alcohol dehydrogenase then converts acetaldehyde to ethanol.

Thus, both decarboxylase and dehydrogenase are involved in this process, making option 1 the correct answer.

Net ATP production when one molecule of glucose is fermented to alcohol or lactic acid:

1. When glucose ferments, there is a net gain of two ATP molecules in the glycolysis process.
2. Both lactic acid and alcoholic fermentation proceed in the same way.
3. When a glucose molecule is partly oxidised to make two molecules of pyruvate, glycolysis produces four molecules of ATP.
4. Because two ATPs are used in the first stages of glycolysis, there is a net gain of two ATP molecules.