Cellular Respiration, Cellular Respiration: Aerobic Vs Anaerobic: Anaerobic And Aerobic Respiration

What Is Cellular Respiration?

Cellular respiration is the biochemical process by which glucose is converted into ATP, the key form of energy in cells, in a series of steps involving metabolic pathways. It is generally the process through which most of the energy that one needs to perform several cellular activities is acquired.

Cellular respiration is the oxidation of sugar that forms both ATP and water as products, with the byproduct being carbon dioxide. It involves three key steps: glycolysis, Krebs cycle, and electron transport chain. It refers to the process through which living organisms obtain energy from food to stay alive, grow, and repair or replace damaged cell structures.

Types Of Cellular Respiration

There are two main types of cellular respiration. These are based on the presence or absence of oxygen.

• Aerobic respiration which requires oxygen and the glucose is completely oxidised.

• Anaerobic respiration which takes place without oxygen and the glucose is partially oxidised.

Aerobic Respiration

Aerobic respiration is a process which requires oxygen and the final product is that glucose is completely broken down into carbon dioxide, water, and ATP. This type of respiration is a common occurrence. It can be represented by the equation:

Glucose + O2 → Water + CO2 + Energy

Anaerobic Respiration

Anaerobic respiration takes place in the absence of oxygen and involves the partial breakdown of glucose. Some other compounds are also formed in addition to carbon dioxide. This type of respiration is of rare occurrence but common in microorganisms like yeasts. It can be represented by the equation:

Glucose → Lactic acid + Small amount of energy

Stages of Aerobic Respiration

The detailed stages are given below:

Glycolysis

• Location: Cytoplasm

• Process: Breakdown of glucose into pyruvate

• Products: ATP and NADH

Krebs Cycle

• Location: Mitochondrial matrix

• Process: Oxidation of Acetyl-CoA

• Products: NADH, FADH2, and ATP

Electron Transport Chain

• Location: Inner mitochondrial membrane

• Process: Oxygen acts as the final electron acceptor, forming water

• Products: Proton gradient and ATP synthesis

• Efficiency: High - 36-38 ATP per glucose molecule

Anaerobic Respiration Pathways

The types of anaerobic respiration are:

Lactic Acid Fermentation

• Occurs in: Muscle cells

• Process: Pyruvate converted to lactic acid

• Significance: Regeneration of NAD+

Alcoholic Fermentation

• Occurs in: Yeast and some bacteria

• Process: Pyruvate converted to ethanol and CO2

• Significance: Regeneration of NAD+

• ATP Yield: Lower (about 2 ATP per glucose molecule)

Aerobic vs Anaerobic Respiration (Table)

The difference between aerobic and anaerobic respiration includes:

Significance of Cellular Respiration

The details are given below:

• Maintains sustained activity in multicellular organisms.

• Required in complex organisms to perform energy-consuming activities.

• Useful in low oxygen conditions where aerobic respiration cannot be performed.

• Forms the base of industrial processes of fermentation, e.g., brewing and baking.

Cellular Respiration NEET MCQs (With Answers & Explanations)

Important topics for NEET are:

• Stages of Aerobic respiration

• Types of Anaerobic respiration

• Aerobic vs Anaerobic respiration

Practice Questions for NEET

Q1. Life without air would be

1. Reductional

2. Free from oxidative damage

3. Impossible

4. Anaerobic

Correct answer: 4) Anaerobic

Explanation:

Anaerobic means 'in the absence of molecular oxygen', so life without air would be anaerobic. The atmosphere of Earth at the time of the origin of life was without free oxygen atoms, so the primitive atmosphere was reducing. In such an environment, early organisms likely relied on anaerobic processes like fermentation for energy production. This condition set the stage for the evolution of aerobic organisms once oxygen became more abundant in Earth's atmosphere.

Hence, the correct answer is option 4) Anaerobic.

Q2. The ultimate electron acceptor of respiration in an aerobic organism is

1. Cytochrome

2. Oxygen

3. Hydrogen

4. Glucose

Correct answer: 2) Oxygen

Explanation:

Oxygen is the final electron acceptor in the electron transport chain during aerobic respiration.
This process involves the transmission of electrons via a sequence of protein complexes in the mitochondrial membrane, which eventually combine with protons and oxygen to produce water (H2O).
Because of its high electronegativity, oxygen is very good at taking up electrons, which promotes oxidative phosphorylation, which produces ATP.
The electron transport chain would stop working in the absence of oxygen, forcing aerobic organisms to rely on less effective energy-producing mechanisms like fermentation or anaerobic respiration.

Hence, the correct answer is option 2)oxygen.

Q3. Pasteur effect is due to

1. Change from aerobic to anaerobic

2. Rapid utilization of ATP

3. Non-synthesis of ATP

4. Producing oxygen to anaerobically respiring structure

Correct answer: 4) Producing oxygen to anaerobically respiring structure

Explanation:

Pasteur effect -

Change from anaerobic to aerobic condition decreases the rate of sugar breakdown and CO2 evolution. The Pasteur effect describes how cells shift from anaerobic fermentation to aerobic respiration when oxygen becomes available, resulting in a more efficient energy production process. This transition decreases the need for fermentation, reducing the production of byproducts like ethanol and lactic acid. The increased ATP yield from aerobic respiration supports the cell's energy requirements more effectively than anaerobic metabolism.

Hence, the correct option is 4) Producing oxygen to an anaerobically respiring structure.