Question 1

Q1: Differentiate between (a) Respiration and Combustion (b) Glycolysis and Krebs' cycle (c) Aerobic respiration and Fermentation

Accepted Answer

Question 2

Q10: Define RQ . What is its value for fats?

Accepted Answer

Definition of RQ (Respiratory Quotient): The Respiratory Quotient (RQ), or respiratory ratio, is defined as the ratio of the volume of carbon dioxide ($CO_2$) evolved to the volume of oxygen ($O_2$) consumed during respiration. Mathematically, it is expressed as: $$RQ = \frac{	ext{volume of } CO_2...

Question 3

Q11: What is oxidative phosphorylation?

Accepted Answer

Oxidative phosphorylation is the process of synthesizing ATP from ADP and inorganic phosphate (Pi) using the energy released during the oxidation of reduced coenzymes ($NADH+H^+$ and $FADH_2$) via the electron transport system (ETS). Key features of oxidative phosphorylation: 1.  Location: It takes...

Question 4

Q12: What is the significance of step-wise release of energy in respiration?

Accepted Answer

The step-wise release of energy during respiration is of great significance for the living cell. If the large amount of energy contained in a glucose molecule were released in a single step, as in combustion, most of it would be liberated as heat and would not be usable by the cell. It could also da...

Question 5

Q2: What are respiratory substrates? Name the most common respiratory substrate.

Accepted Answer

Respiratory Substrates: The compounds that are oxidised during the process of respiration to release energy are known as respiratory substrates. These are typically macromolecules from which the cell can derive energy. Examples of respiratory substrates include carbohydrates, fats, proteins, and eve...

Question 6

Q3: Give the schematic representation of glycolysis?

Accepted Answer

Glycolysis is the process of partial oxidation of glucose to form two molecules of pyruvic acid. It occurs in the cytoplasm and involves a series of ten enzyme-catalysed reactions. The pathway is often referred to as the EMP pathway. A schematic representation of the steps of glycolysis is as follow...

Question 7

Q4: What are the main steps in aerobic respiration? Where does it take place?

Accepted Answer

Aerobic respiration is the process that leads to the complete oxidation of organic substances in the presence of oxygen, releasing $CO_2$, water, and a large amount of energy. The main steps in aerobic respiration are: 1.  Glycolysis: The breakdown of one molecule of glucose into two molecules of py...

Question 8

Q5: Give the schematic representation of an overall view of Krebs' cycle.

Accepted Answer

The Krebs' cycle, also known as the tricarboxylic acid (TCA) cycle or citric acid cycle, is a series of reactions that completely oxidizes acetyl CoA derived from carbohydrates, fats, and proteins into $CO_2$ and water to generate energy. It occurs in the mitochondrial matrix. A schematic representa...

Question 9

Q6: Explain ETS.

Accepted Answer

Electron Transport System (ETS) The Electron Transport System (ETS) is a metabolic pathway located on the inner mitochondrial membrane. Its primary function is to release and utilise the energy stored in the reduced coenzymes, $NADH+H^+$ and $FADH_2$, which are generated during glycolysis and the Kr...

Question 10

Q7: Distinguish between the following: (a) Aerobic respiration and Anaerobic respiration (b) Glycolysis and Fermentation (c) Glycolysis and Citric acid Cy...

Accepted Answer

Question 11

Q8: What are the assumptions made during the calculation of net gain of ATP?

Accepted Answer

The calculation of a net gain of 38 ATP molecules for every glucose molecule oxidised is a theoretical exercise. This calculation is based on the following key assumptions, which are not entirely valid in a living system: 1.  Sequential and Orderly Pathway: It is assumed that there is a sequential,...

Question 12

Q9: Discuss "The respiratory pathway is an amphibolic pathway."

Accepted Answer

The respiratory pathway is traditionally considered a catabolic process because it involves the breakdown of complex substrates like glucose, fats, and proteins to release energy. However, this view is an oversimplification. The respiratory pathway is more accurately described as an amphibolic pathw...

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