The bacteria that cause tetanus can be killed only by prolonged heating at temperatures considerably above boiling. This suggests that tetanus bacteria
a. Have cell walls containing peptidoglycan.
b. Secrete endotoxins.
c. Are autotrophic.
d. Produce endospores.

Verified step by step guidance

1. Understand the problem: The question is asking which characteristic of tetanus bacteria allows them to survive prolonged heating at temperatures above boiling. This requires knowledge of bacterial structures and survival mechanisms.
2. Recall the concept of endospores: Endospores are highly resistant structures formed by certain bacteria to survive extreme conditions, including high temperatures, desiccation, and chemical exposure. This is a key survival mechanism for some bacteria.
3. Evaluate the options: Analyze each answer choice: (a) Peptidoglycan is a component of bacterial cell walls, but it does not provide resistance to extreme heat. (b) Endotoxins are toxins released by bacteria, but they do not explain heat resistance. (c) Autotrophic bacteria produce their own food, but this is unrelated to heat resistance. (d) Endospores are specifically designed to withstand extreme conditions, including prolonged heating.
4. Connect the information: Based on the explanation above, the ability to survive prolonged heating is most likely due to the production of endospores, as this is a well-documented survival strategy for certain bacteria, including those that cause tetanus.
5. Conclude the reasoning: The correct answer is likely (d) because endospores are the only feature listed that directly explains the bacteria's ability to survive prolonged heating at temperatures above boiling.

Key Concepts

Endospores

Endospores are highly resistant structures formed by certain bacteria, allowing them to survive extreme conditions, including high temperatures and desiccation. When environmental conditions become unfavorable, bacteria like Clostridium tetani (the causative agent of tetanus) can form endospores, which can remain dormant for long periods. This resilience explains why prolonged heating is necessary to kill these bacteria.

Peptidoglycan

Peptidoglycan is a polymer that forms a protective layer in the cell walls of bacteria, providing structural integrity. While it is a characteristic feature of bacterial cells, the presence of peptidoglycan does not directly relate to the heat resistance of tetanus bacteria. Instead, it is more relevant to the classification of bacteria as Gram-positive or Gram-negative.

Autotrophic vs. Heterotrophic

Autotrophic organisms can produce their own food from inorganic substances, while heterotrophic organisms rely on consuming organic material. Tetanus bacteria, being heterotrophic, obtain nutrients from their environment, typically from the host's tissues. This distinction is important for understanding bacterial metabolism but does not explain the heat resistance of tetanus bacteria.