Introduction / Context:
Microorganisms can break down organic materials in both the presence and absence of oxygen. These processes are given different names in biology and industry. This question focuses on the term used for bacterial decomposition of biological material when oxygen is absent, that is, under anaerobic conditions. Understanding these processes is important in microbiology, food technology, and environmental science.
Given Data / Assumptions:
- Biological material is being decomposed by bacteria.
- The condition specified is anaerobic, meaning oxygen free.
- The options are fermentation, fertilization, contamination, and composting.
Concept / Approach:
Fermentation is defined as the breakdown of organic compounds, especially sugars, by microorganisms under anaerobic conditions, releasing energy and formation of products such as alcohol, acids, or gases. Fertilization refers to fusion of gametes, contamination refers to unwanted presence of microbes, and composting is usually aerobic decomposition of organic waste. The correct approach is to recall that fermentation explicitly describes anaerobic bacterial or yeast activity on organic matter.
Step-by-Step Solution:
Step 1: Recognize that anaerobic decomposition means that bacteria break down material without using oxygen.
Step 2: Recall that fermentation is a metabolic process in which cells convert sugars into other products in the absence of oxygen.
Step 3: Note that common examples include yeast fermenting sugar to produce alcohol and bacteria producing lactic acid in curd.
Step 4: Understand that fertilization is a reproductive process involving sperm and egg, not decomposition.
Step 5: Recognize that contamination refers to accidental introduction of microbes into something, and does not specifically describe a planned decomposition process.
Step 6: Remember that composting generally describes aerobic decomposition of organic waste, often assisted by turning the material to let in air.
Step 7: Conclude that the correct term for anaerobic bacterial decomposition is fermentation.
Verification / Alternative check:
Standard microbiology definitions and food processing examples consistently use the term fermentation for processes like making bread, alcohol, curd, and pickles, all of which involve microbial activity under low oxygen or no oxygen conditions. Anaerobic digesters that produce biogas also involve fermentation of organic waste, often referred to as anaerobic fermentation. Composting, in contrast, is described as aerobic and requires air circulation. This cross check confirms that fermentation is the correct answer when anaerobic conditions are specifically mentioned.
Why Other Options Are Wrong:
Fertilization: This is the union of male and female gametes to form a zygote and has nothing to do with bacterial decomposition.
Contamination: This term describes unwanted impurity or microbial invasion but does not define a controlled anaerobic breakdown process.
Composting: Composting is usually aerobic, meaning it requires oxygen; when oxygen is limited, it may become smelly and inefficient, which is not ideal composting.
Common Pitfalls:
Students may confuse composting with any type of decomposition and forget the role of oxygen. Another pitfall is to associate fermentation only with yeast and alcohol, without noticing that the definition includes broader anaerobic breakdown by bacteria as well. Remembering that fermentation is a general term for anaerobic metabolism and that composting is aerobic helps avoid these mistakes in exam questions that emphasize oxygen conditions.
Final Answer:
Bacterial decomposition of biological material under anaerobic conditions is called
Fermentation.
Discussion & Comments