Introduction
Respiration in bacteria is an important topic from NCERT Biology (Class 11) and is frequently asked in NEET examination. Bacteria show great diversity in their respiratory mechanisms. In this post, you will study types of respiration in bacteria, important NCERT points, and quick revision notes for NEET.
Types of Respiration in Bacteria
Bacteria can perform different types of respiration depending on the availability of oxygen.
Based on oxygen requirement, respiration in bacteria is of following types:
Aerobic respiration
Anaerobic respiration
Facultative anaerobic respiration
Obligate anaerobic respiration
Aerobic Respiration in Bacteria
Aerobic respiration occurs in the presence of oxygen.
Key points:
Complete oxidation of glucose
Oxygen acts as final electron acceptor
End products are carbon dioxide (CO₂) and water (H₂O)
Maximum amount of energy (ATP) is released
Examples:
Pseudomonas
Mycobacterium
📌 NCERT Point:
In bacteria, respiratory enzymes are present in the plasma membrane, not in mitochondria.
Anaerobic Respiration in Bacteria
Anaerobic respiration occurs in the absence of oxygen.
Key points:
Incomplete oxidation of glucose
End products include lactic acid, ethanol or organic acids
Less amount of ATP is produced compared to aerobic respiration
Examples:
Clostridium
Lactobacillus
Facultative Anaerobic Bacteria
Facultative anaerobes can survive both in presence and absence of oxygen.
Characteristics:
Perform aerobic respiration when oxygen is available
Switch to anaerobic respiration in absence of oxygen
Examples:
Escherichia coli
Yeast
📌 NEET Focus: Facultative anaerobes are highly adaptable bacteria.
Obligate Anaerobic Bacteria
Obligate anaerobes can survive only in absence of oxygen.
Characteristics:
Oxygen is toxic for these bacteria
Perform only anaerobic respiration
Example:
Clostridium tetani
Site of Respiration in Bacteria (Very Important)
Bacteria do not have mitochondria
Respiratory enzymes are present in the plasma membrane
Mesosomes help in respiration by increasing surface area
📌 Direct NCERT Line (Exam Important):
“In bacteria, respiratory enzymes are located in the plasma membrane.”
Important NCERT Points for NEET
Bacteria show all types of respiration
Plasma membrane acts as respiratory surface
Mesosomes increase surface area for respiration
Facultative anaerobes are metabolically flexible
Difference Between Aerobic and Anaerobic Respiration in Bacteria
| Feature | Aerobic | Anaerobic |
|---|---|---|
| Oxygen | Required | Not required |
| Oxidation | Complete | Incomplete |
| ATP yield | High | Low |
| End products | CO₂ + H₂O | Acids / Alcohol |
Quick Revision (NEET Ready)
Respiration = release of energy
Aerobic → more ATP
Anaerobic → less ATP
Plasma membrane = site of respiration
Facultative anaerobes survive in both conditions
Conclusion
Respiration in bacteria is a highly scoring topic for NEET Biology. Understanding types of respiration, site of respiration, and NCERT keywords is essential for exam success. Revise this topic regularly and focus on NCERT lines for maximum accuracy.
