Bioremediation - Class 12 Biotechnology - Chapter 11 - Notes, NCERT Solutions & Extra Questions
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Extra Questions - Bioremediation | NCERT | Biotechnology | Class 12
The amount of oxygen required by bacteria in water to break down wastes into simple inorganic substances is called ___
Biological Oxygen Demand (BOD) is the amount of dissolved oxygen required by aerobic biological organisms to break down organic material in a given water sample at a certain temperature over a specific time period.
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Which microorganisms are used in sewage water treatment and what is their role?
In sewage water treatment, a variety of microorganisms play a crucial role, primarily involving bacteria, fungi, protozoa, and algae. Bacteria such as Pseudomonas, Bacillus, and Nitrosomonas are pivotal as they break down organic pollutants into simpler, non-toxic compounds. Fungi contribute to the decomposition of tough organic materials and help in mineralizing complex compounds. Protozoa, such as amoeba and ciliates, consume bacteria, helping to regulate bacterial populations and contributing to the clarity of the treated water. Algae in the system produce oxygen through photosynthesis, essential for aerobic bacterial activities. Together, these organisms degrade organic materials, reduce pathogens, and stabilize the treated water before it is released back into the environment.
Explain as to how biological oxygen demand represents the condition of sewage water?
Biological Oxygen Demand (BOD) is a critical metric that quantifies the amount of dissolved oxygen needed by aerobic microorganisms to decompose organic matter in water. When BOD values are high, it indicates that the sewage water contains a high level of organic pollutants. This implies a greater demand for oxygen required by the microorganisms to decompose these materials, thus reflecting poor water quality. Conversely, low BOD values signify lesser organic content and better water quality. Monitoring BOD is essential for assessing the effectiveness of wastewater treatment processes and ensuring that discharged water does not adversely affect aquatic ecosystems due to oxygen depletion.
How does any toxic substance get biomagnified among organisms? Explain in brief.
Biomagnification refers to the increase in concentration of a toxic substance in the tissues of organisms at each level of the food chain. Primarily, toxic substances are often persistent pollutants, such as heavy metals or certain pesticides, that are not easily broken down by natural processes. These toxins are absorbed by primary producers like plankton or plants from the environment. When herbivores eat these producers, the toxins are absorbed into their bodies and accumulate because they are not efficiently metabolized or excreted. As carnivores consume herbivores, the concentration of the toxin increases because they ingest multiple contaminated organisms. This pattern continues up the food chain, leading to highest concentrations in top predators, significantly impacting their health and survival.
What are xenobiotic compounds? How do these compounds affect the productivity of soil?
Xenobiotic compounds are synthetic chemicals not naturally found in nature, introduced into the environment through human activities. These include pesticides, industrial chemicals, and pharmaceuticals. Their structure often makes them resistant to natural degradation processes, leading them to accumulate in soils.
The accumulation of these compounds can adversely affect soil productivity by altering microbial communities that are essential for nutrient cycling. This disruption can lead to a decrease in soil fertility, impacting plant growth and agricultural yields. Moreover, xenobiotics can also contaminate crops, posing health risks to wildlife and humans. Thus, their presence in soil can have long-term detrimental effects on ecosystem health and agricultural productivity.
Discuss the process of aerobic and anaerobic decomposition of sewage waste water treatment.
The treatment of sewage wastewater involves both aerobic and anaerobic decomposition processes to effectively reduce pollutants. In the aerobic process, oxygen is used to break down organic matter. Microorganisms consume organic compounds, converting them into carbon dioxide, water, and biomass. This typically occurs in treatments like activated sludge systems or biofilters, where air is pumped to facilitate the decomposition.
Conversely, the anaerobic process occurs in the absence of oxygen. It primarily takes place in anaerobic digesters where microorganisms break down organic matter to produce methane, carbon dioxide, and other gases, a process also beneficial for generating biogas. Both methods are essential for reducing the environmental impact of sewage waste, turning hazardous matter into stable, less toxic forms.
What are the different types of solid wastes produced?
Solid wastes can be broadly categorized into two main types: biodegradable waste and non-biodegradable waste.
- Biodegradable waste includes organic materials that naturally decompose through microbial action. Sources include agricultural residues, kitchen scraps, garden waste, and other natural materials. These can be converted into compost or other forms of soil conditioner.
- Non-biodegradable waste comprises materials that do not easily decompose. This category includes plastics, metals, glass, and synthetic fibers. These materials often require specific recycling processes to manage their disposal or can accumulate in the environment, causing pollution.
Proper management of both types is crucial to minimize environmental impact and promote sustainable waste handling practices.
Discuss the role of different microorganisms in the process of composting of solid waste.
In the composting process, diverse microorganisms play crucial roles in breaking down organic matter into compost. Bacteria constitute about 80-90% of the microbial population in compost and are vital for rapid decomposition, especially during the initial and thermophilic phases. Actinomycetes, a type of filamentous bacteria, degrade tough organic materials like cellulose and lignin, crucial for breaking down tougher plant materials. Fungi, including molds and yeast, contribute by decomposing complex organic substances in the outer layers of compost. Protozoans and invertebrates like earthworms further enhance decomposition by processing organic materials and contributing to the physical breakdown and aeration of the compost. These microorganisms work synergistically, ensuring efficient decomposition and nutrient cycling in composting systems.
How are pesticides harmful for non-target organisms?
Pesticides are chemicals used to eliminate pests, but they often have unintended consequences for non-target organisms. Bioaccumulation occurs when these chemicals accumulate in the bodies of non-target species over time, leading to higher concentrations at higher trophic levels, a process known as biomagnification. This can cause reproductive failure, hormonal disruption, and death in wildlife. Pesticides can also reduce biodiversity by killing species that are not pests, such as pollinators and predators of pests, which are vital for maintaining the balance of ecosystems. Additionally, toxic residues of pesticides can remain in soil and water, leading to long-term exposure and harm to various organisms.
Briefly explain as to how microorganisms can bioremediate toxic pesticides into harmless and non-toxic compounds.
Bioremediation of pesticides involves utilizing the natural capabilities of microorganisms to degrade or transform harmful pesticides into harmless compounds. Microorganisms such as bacteria, fungi, and algae possess specific enzymes that can break down complex pesticide molecules. Key enzymatic reactions involved in this process include oxidation, reduction, hydrolysis, and conjugation.
Enzymes like cytochrome P450, esterases, and peroxidases play crucial roles. For instance, cytochrome P450 oxidatively breaks down various pesticides, while esterases are responsible for the hydrolytic breakdown of organophosphate pesticides. Through these biochemical reactions, microorganisms convert toxic pesticides into simpler, non-toxic, and often water-soluble compounds, effectively reducing their environmental and health risks. This process not only detoxifies the environment but also promotes the sustainability of ecosystems by minimizing chemical residues.
Which of the following compounds can be removed from waste water during treatment using lime?
(a) Organic compound
(b) Phosphorous salts
(c) Ammonia
(d) Urea
Phosphorous salts can be removed from wastewater during treatment using lime. Lime reacts with phosphorus inorganic compounds in the effluently to form insoluble calcium phosphate (Ca₃(PO₄)₂), which then settles to the bottom of the settling tank and is removed. Therefore, the correct answer is:
(b) Phosphorous salts
Maximum decomposition of water takes place during:
(a) Primary treatment only
(b) Primary and Secondary treatment both
(c) Secondary treatment only
(d) Secondary and tertiary treatment both
The maximum decomposition of organic matter in wastewater, including water, typically occurs during the secondary treatment. This stage primarily involves biological processes where microorganisms break down organic material. Hence, the correct answer is:
(c) Secondary treatment only.
Which enzyme is mainly responsible for hydrolytic breakdown of pesticides?
(a) Peroxidare
(b) Oxidare
(c) Cytochrous P 450
(d) Esterare
The enzyme mainly responsible for the hydrolytic breakdown of pesticides is Esterase. Hence, the correct answer is:
(d) Esterase
Which of the following is not a strategy of bioremediation?
(a) Sludge digestion
(b) Composting
(c) Slury bioreactor
(d) Biopiles
The correct answer is:
(a) Sludge digestion
This option is not mentioned as a strategy of bioremediation in the provided chapter. Instead, the text discusses slurry bioreactors, composting, and biopiles as strategies for bioremediation.
Assertion: Bioremediation is a process through which toxic pesticides can be completely removed.
Reason: Microorganisms can be used for bioremediation of toxic chemicals.
(a) Both assertion and reason are true and the reason is correct explanation of assertion.
(b) Both assertion and reason are true but the reason is not the correct explanation of the assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false.
(b) Both assertion and reason are true but the reason is not the correct explanation of the assertion.
Explanation:
- Assertion: True. Bioremediation indeed can completely remove toxic pesticides, exploiting the natural capabilities of microorganisms to degrade or transform harmful chemicals into less toxic forms.
- Reason: True. Microorganisms indeed play a central role in bioremediation processes by utilizing their enzymatic systems to break down complex pollutants.
- However, the reason given does not directly explain the process through which complete removal (as mentioned in the assertion) specifically occurs, only that microorganisms are employed in bioremediation. Thus, while both statements are true, the reason does not serve as a direct explanation for the assertion.
Based on the colour coding and type of container for disposal of health care waste, choose the correct match:
(a) Yellow — recyclable plastic waste
(b) Red — metallic body
(c) White — sharp metals, needle, syringes
(d) Blue — general health care waste
The correct match based on the provided information about the colour coding and type of container for the disposal of health care waste is:
(c) White — sharp metals, needle, syringes
This corresponds with the description provided in the chapter where the white colour code is used for waste that includes used, discarded and contaminated metal sharps, needles, syringes with fixed needles, and other sharp objects that may cause puncture and cuts. The other options are incorrect as per the provided details in the chapter.
What is the basis of classifying organisms into four risk groups?
Biomedical wastes are classified into four risk groups based on the level of risk they pose to individuals and communities. These classifications provide guidelines to optimize safety measures during handling and disposal.
- Risk Group 1: Contains organisms that are unlikely to cause disease in humans or animals and present no or low risk to individual and community.
- Risk Group 2: Includes organisms posing a moderate risk to individuals and low risk to the community, typically causing human or animal disease with preventive measures available.
- Risk Group 3: Consists of pathogens that cause serious human or animal disease, representing a high individual risk but low community risk, with effective treatment available.
- Risk Record 4: Organizations in this group cause severe human or animal disease, pose a high risk to both individuals and the community, and often lack effective treatments and preventive measures.
Overall, these risk categories guide handling protocols to protect public health and safety effectively.
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Comprehensive Bioremediation Class 12 Notes: A Complete Guide
Introduction to Bioremediation
What is Bioremediation?
Bioremediation is the process of using living organisms, primarily microbes, to degrade and detoxify pollutants in the environment. It's an eco-friendly way of managing waste and mitigating pollution through biodegradation.
Historical Background
The concept of bioremediation has been around for decades, but significant strides were made in the late 20th century. One of the pioneering figures in this field was Ananda Mohan Chakrabarty, who developed genetically engineered bacteria capable of degrading oil spills.
Types of Bioremediation
In Situ Bioremediation
In situ bioremediation involves treating the contaminated material at the site without removing it. This method is less disruptive and more cost-effective.
Ex Situ Bioremediation
Ex situ bioremediation involves removing the contaminated material to treat it elsewhere. This method can be more controlled and effective, but it is usually more expensive and disruptive.
Here is a diagram showing both in situ and ex situ bioremediation processes:
Mechanisms of Bioremediation
How Bioremediation Works
Bioremediation works through the metabolic processes of microorganisms. These microbes break down pollutants into less harmful substances, often using them as a source of energy.
Microbial Processes
Microbial degradation can be aerobic (in the presence of oxygen) or anaerobic (in the absence of oxygen). Different microbes work in different conditions to degrade various pollutants.
Role of Enzymes
Enzymes such as cytochromes, esterases, and oxidases play a crucial role in breaking down complex pollutants into simpler, non-toxic forms.
Applications of Bioremediation
Wastewater Treatment
Bioremediation is extensively used in wastewater treatment to remove organic matter, heavy metals, and other contaminants. Activated sludge process, trickling filters, and oxidation ponds are common methodologies.
Soil Remediation
Contaminated soils, especially those affected by industrial activities, can be cleaned using bioremediation. Techniques include land farming, slurry bioreactors, and composting.
Oil Spills
Oil spills pose a significant environmental threat. Microorganisms like Pseudomonas are employed to degrade hydrocarbons present in crude oil.
Pesticides
Bioremediation helps in breaking down persistent pesticides such as DDT and organophosphates into harmless substances.
Heavy Metals
Certain bacteria can bioaccumulate heavy metals like mercury and lead, thereby reducing their toxicity.
Advantages and Limitations
Pros and Cons of Bioremediation
Advantages
- Environmentally Friendly: Uses natural processes to detoxify pollutants.
- Cost-Effective: Generally cheaper than physical or chemical methods.
- Versatility: Can be applied to various pollutants and environments.
Limitations
- Time-Consuming: The process can be slow and may require months or years.
- Site-Specific: Effectiveness can vary depending on the environment and type of pollutant.
- Limited Scope: Not effective for all types of contaminants, especially those highly toxic to microorganisms.
Key Microorganisms in Bioremediation
Common Microorganisms Used in Bioremediation
Bacteria
Bacteria such as Pseudomonas, Bacillus, and Rhodococcus play a significant role in breaking down complex organic pollutants.
Fungi
Fungi like white-rot fungi are effective in degrading lignin and certain organic pollutants.
Algae
Algae can absorb heavy metals and degrade certain organic pollutants, making them useful in aquatic environments.
Case Study: Ananda Mohan Chakrabarty and Bioremediation
The Pioneering Work of Ananda Mohan Chakrabarty
Development of Genetically Engineered Pseudomonas
Ananda Mohan Chakrabarty's development of a genetically engineered Pseudomonas strain that could degrade oil was a landmark achievement in bioremediation.
The Diamond v. Chakrabarty Case
This Supreme Court case in 1980 allowed Chakrabarty to patent his genetically modified organism, setting a precedent for future biotechnological innovations.
Bioremediation in Class 12 Biology
Important Concepts
Students will delve into the mechanisms, types, and applications of bioremediation, focusing on microbial processes and environmental impact.
Real-World Examples
Case studies like the Exxon Valdez oil spill and bioremediation of pesticides in agricultural lands are often discussed.
Exam Preparation Tips
- Understand key terms and definitions.
- Focus on the processes and types of bioremediation.
- Familiarise yourself with real-world applications and case studies.
Comparing Bioremediation with Phytoremediation
Difference Between Bioremediation and Phytoremediation
Definitions and Mechanisms
- Bioremediation: Uses microbes to degrade pollutants.
- Phytoremediation: Uses plants to absorb, detoxify, or stabilise pollutants.
Examples and Applications
- Bioremediation: Treatment of oil spills, wastewater, and industrial contaminants.
- Phytoremediation: Removal of heavy metals and excess nutrients using plants like mustard and sunflowers.
Future Prospects and Conclusion
The Future of Bioremediation
Innovations and Research
Ongoing research is focused on genetically modifying microorganisms to enhance their bioremediation capabilities.
Environmental Impact
Bioremediation offers a sustainable way to manage pollution, helping to restore ecosystems and protect public health.
Summary and Takeaways
Bioremediation is a powerful tool in environmental management, utilising natural processes to detoxify pollutants. Understanding its mechanisms, applications, and limitations is crucial for students and environmental scientists alike.
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