Find the best tutors and institutes for Class 12 Tuition
Q11(c):
Discuss briefly the following:
(c) Ultraviolet B
Solution :
1. Theoretical Foundation of Ultraviolet-B (UV-B) Radiation
Ultraviolet-B (UV-B) constitutes the electromagnetic spectrum region with wavelengths ranging from $280\text{ nm}$ to $315\text{ nm}$. It sits between UV-C (the most energetic, largely absorbed by the atmosphere) and UV-A (longer wavelength, less damaging). [Per the Electromagnetic Spectrum classification].
2. Atmospheric Interaction and The Ozone Layer
The concentration of stratospheric ozone ($O_3$) acts as a natural filter for UV radiation. While UV-C is entirely absorbed by ozone and dioxygen, UV-B is partially absorbed. The depletion of the ozone layer, primarily caused by chlorofluorocarbons (CFCs) and other ozone-depleting substances, leads to an increased flux of UV-B reaching the Earth’s surface. [Reference: Montreal Protocol mechanisms].
3. Biological Impact and Pathophysiology
UV-B is highly energetic and possesses the capacity to break chemical bonds, particularly affecting organic molecules such as DNA and proteins. The biological consequences are categorized as follows:
- DNA Damage: UV-B radiation induces the formation of pyrimidine dimers (specifically thymine dimers) in DNA strands. If not repaired by DNA repair mechanisms (such as photolyases), these mutations lead to carcinogenesis.
- Dermatological Effects: Acute exposure results in erythema (sunburn). Chronic, long-term exposure is strongly correlated with an increased incidence of basal cell carcinoma, squamous cell carcinoma, and malignant melanoma.
- Ocular Impact: The cornea and lens are highly sensitive to UV-B. High-intensity exposure can cause photokeratitis and is a primary causative factor in the development of senile cataracts.
- Immune Suppression: UV-B exposure alters the distribution and function of antigen-presenting cells (Langerhans cells) in the skin, leading to local immunosuppression.
4. Visual Representation of UV-B Atmospheric Interaction
5. Comparative Analysis of UV Effects
| Radiation Type | Wavelength (nm) | Biological Impact |
|---|---|---|
| UV-C | 100–280 | Lethal; fully absorbed by $O_3$ |
| UV-B | 280–315 | High; DNA damage/Mutagenic |
| UV-A | 315–400 | Moderate; skin aging/tanning |
Final Solution: Ultraviolet-B (UV-B) is a high-energy electromagnetic radiation (280–315 nm) that poses significant biological risks due to its ability to induce DNA mutagenesis, accelerate skin aging, cause cataract formation, and suppress the human immune system. Its reach to the Earth's surface is regulated by the stratospheric ozone layer, making ozone depletion a critical public health concern.
More Questions from Class 12 Biology Environmental Issues EXERCISES
- Q1: What are the various constituents of domestic sewage? Discuss the effects of sewage discharge on a river.
- Q1: What are the various constituents of domestic sewage? Discuss the effects of sewage discharge on a river.
- Q2: List all the wastes that you generate, at home, school or during your trips to other places. Could you very easily reduce the generation of these wastes? Which would be difficult or rather impossible to reduce?
- Q2: List all the wastes that you generate, at home, school or during your trips to other places. Could you very easily reduce the generation of these wastes? Which would be difficult or rather impossible to reduce?
- Q3: Discuss the causes and effects of global warming. What measures need to be taken to control global warming?
- Q3: Discuss the causes and effects of global warming. What measures need to be taken to control global warming?
- Q4: Match the items given in column A and B:
- Q4: Match the items given in column A and B: Column A Column B (a) Catalytic converter (i) Particulate matter (b) Electrostatic precipitator (ii) Carbon monoxide and nitrogen oxides (c) Earmuffs (iii) High noise level (d) Landfills (iv) Solid wastes
- Q5(a): Write critical notes on the following: (a) Eutrophication
- Q5(a): Write critical notes on the following: (a) Eutrophication
- Q5(b): Write critical notes on the following: (b) Biological magnification
- Q5(b): Write critical notes on the following: (b) Biological magnification
- Q5(c): Write critical notes on the following: (c) Groundwater depletion and ways for its replenishment
- Q5(c): Write critical notes on the following: (c) Groundwater depletion and ways for its replenishment
- Q6: Why does ozone hole form over Antarctica? How will enhanced ultraviolet radiation affect us?
- Q6: Why does ozone hole form over Antarctica? How will enhanced ultraviolet radiation affect us?
- Q7: Discuss the role of women and communities in protection and conservation of forests.
- Q7: Discuss the role of women and communities in protection and conservation of forests.
- Q8: What measures, as an individual, would you take to reduce environmental pollution?
- Q8: What measures, as an individual, would you take to reduce environmental pollution?
- Q9(a): Discuss briefly the following: (a) Radioactive wastes
- Q9(a): Discuss briefly the following: (a) Radioactive wastes
- Q9(b): Discuss briefly the following: (b) Defunct ships and e-wastes
- Q9(b): Discuss briefly the following: (b) Defunct ships and e-wastes
- Q9(c): Discuss briefly the following: (c) Municipal solid wastes
- Q9(c): Discuss briefly the following: (c) Municipal solid wastes
- Q10: What initiatives were taken for reducing vehicular air pollution in Delhi? Has air quality improved in Delhi?
- Q10: What initiatives were taken for reducing vehicular air pollution in Delhi? Has air quality improved in Delhi?
- Q11(a): Discuss briefly the following: (a) Greenhouse gases
- Q11(a): Discuss briefly the following: (a) Greenhouse gases
- Q11(b): Discuss briefly the following: (b) Catalytic converter
- Q11(b): Discuss briefly the following: (b) Catalytic converter
- Q11(c): Discuss briefly the following: (c) Ultraviolet B
CBSE Solutions for Class 12 Biology Environmental Issues
Chapters in CBSE - Class 12 Biology
- Reproduction in Organisms
- Human Reproduction
- Reproductive Health
- Principles of Inheritance and Variation
- Molecular Basis of Inheritance
- Evolution
- Human Health and Disease
- Strategies for Enhancement in Food Production
- Microbes in Human Welfare
- Biotechnology: Principles and Processes
- Biotechnology and Its Applications
- Organisms and Populations
- Ecosystem
- Biodiversity and Conservation
Top Tutors who teach Environmental Issues
Super Tutor
Shahdara Chitrakoot, Delhi
8 yrs of
Exp
14 students
7157 hrs of classes completed
500
per hour
Online Classes
With years of experience in providing Class 12 tuition, I specialize in teaching both mathematics and computer science. My approach is tailored to meet the rigorous demands of the Class 12 curriculum, focusing on in-depth understanding and application of concepts. In mathematics, I cover a broad spectrum of topics including calculus, algebra, trigonometry, and statistics, ensuring students grasp the fundamental theories and their practical applications. In computer science, my teaching encompasses programming languages such as Java and C++, data structures, algorithms, and database management. I integrate real-world problem-solving techniques and coding practices to prepare students for both exams and future academic endeavors. My lessons are structured to build a strong foundation in both theoretical and practical aspects, using a blend of traditional teaching methods and modern technologies. I employ interactive tools like educational software, online coding platforms, and simulation tools to enhance learning. My classes are supplemented with detailed notes, well-structured PowerPoint presentations, and regular assessments to track progress. I also provide personalized attention to address individual student needs and learning paces. Regular doubt-clearing sessions, practice tests, and revision modules are key components of my teaching strategy. I ensure students are well-prepared for their board exams and competitive entrance tests, emphasizing conceptual clarity and efficient problem-solving techniques. My commitment is to foster a deep understanding and passion for mathematics and computer science, equipping students with the skills and knowledge to excel academically and beyond.
I’ve had an excellent learning experience with Rahul Sir. One of the commendable aspects is that he completed the syllabus well before time, which will provide me with ample opportunity to review and reinforce my understanding of the concepts. He articulates topics with clarity, ensures that the fundamentals are well understood, and always takes time to clear doubts patiently. His teaching style is systematic and engaging, which makes even difficult topics easier to grasp. His mentorship has improved my speed and accuracy. Additionally, I appreciate his punctuality, structured planning of lessons, and the way he motivates students to stay consistent. Overall, he is a dedicated teacher who truly cares about his students’ progress, and I would highly recommend him to anyone seeking quality Math tuition.
Top Tutor
Faridabad, Faridabad
5 yrs of
Exp
14 students
900
per hour
Online Classes
Student's Home
Tutor's home
I am teaching Physics from last 5 years. And within a week after getting classes from me, student falls in love with the subject. Eagerly waits for the next class.
Top Tutor
Malkajgiri D.D.Colony, Hyderabad
20 yrs of
Exp
21 students
1584 hrs of classes completed
500
per hour
Online Classes
32+ years of teaching. Conducted online classes for more than 10 years. Prepared question papers and materials. Teaching students preparing for IIT, VITEE, COMEDK and other entrance examinations. Teach problems from various other authors, other state books and train students for their examinations. Conducted weekly quizzes and unit wise tests. Also conducted mock examinations before the board exam
I'm currently his student. He is a great teacher who teaches according to the students need and he always ensures that the student is comfortable with his teaching and understands the concepts completely. I am very sure that you can choose him as your tutor.
Top Tutor
Chandralok, Lucknow
20 yrs of
Exp
48 students
2294 hrs of classes completed
400
per hour
Online Classes
Tutor's home
It was fabulous. Class 12 kids are very honest in stating if they understood or not and that helps a lot to teach them.
Ragini ma’am is an amazing teacher who explains every concept in a very clear and simple way. Her guidance, support, and constant motivation helped me score really good marks in my boards. Truly grateful for all her hard work and support throughout the year
Top Tutor
Choolissery, Thrissur
20 yrs of
Exp
1 student
446 hrs of classes completed
600
per hour
Online Classes
I'm Sini Jayaraj, and I'm excited to hear about your interest in Class 12 tuition. With over 20 years of experience teaching subjects like Mathematics, Physics, Chemistry, and Science, Teaching is my passion.... Enjoyed well in highschool and higher secondary level.. l'm confident I can help you excel, especially given your immediate start timeline.My background includes a B.Sc., B.Ed., and M.Sc., allowing me to provide a comprehensive understanding of the subjects. I have taught for 214 hours.I focus on making complex topics easy to grasp, perfectly aligning with your goal of simplifying the learning process.Would you be interested in booking a free demo class with me to discuss your specific needs and how I can support you? Or feel free to connect with me to discuss further.Warm regards,Sini Jayaraj secondary levels
Sini mam is very responsible and sinsere teaches. She knows how to teach kids actively &make undestand them concepts clearly.
