Class 12 Biology - WEST-BENGAL
Human Health and Disease
The chapter 'Human Health and Disease' in Class 12 Biology under WBBSE explores the fundamental concepts of health, common infectious and non-infectious diseases, and the human immune system. Students learn about pathogens, life cycles of parasites like Plasmodium causing malaria, and the mechanisms of innate and acquired immunity. The chapter also covers crucial modern health issues such as AIDS, cancer, and the impacts of drug and alcohol abuse. Mastering this chapter is essential for board exams as it carries high weightage, frequently featuring conceptual questions on immunity, lifecycle diagrams, and preventive measures against major diseases.
Start Learning FreeKey Concepts
Pathogens and Diseases
Pathogens are disease-causing organisms like bacteria, viruses, fungi, and protozoans that enter the human body and disrupt normal physiological functions.
Innate and Acquired Immunity
Innate immunity is non-specific defense present from birth, while acquired immunity is pathogen-specific and characterized by memory, involving B and T lymphocytes.
Active and Passive Immunity
Active immunity develops when a host's own body produces antibodies in response to antigens, whereas passive immunity involves the direct transfer of ready-made antibodies.
AIDS (Acquired Immuno Deficiency Syndrome)
A fatal disease caused by HIV (Human Immunodeficiency Virus) which destroys helper T-cells, severely crippling the body's immune system.
Cancer and Oncogenes
Cancer is characterized by uncontrolled, abnormal cell division leading to tumors, caused by the activation of cellular oncogenes or exposure to carcinogens.
Important Formulas
Board Exam Info
In the West Bengal (WBBSE) Class 12 Biology board examination, this chapter typically carries around 6 to 8 marks. Questions frequently include short-answer questions (SAQ) on disease vectors, descriptive long-answer questions (LAQ) detailing the life cycle of the malarial parasite or HIV replication, and differentiation between active-passive immunity or benign-malignant tumors.
Frequently Asked Questions
What is the difference between active and passive immunity?
Active immunity is developed by the individual's own immune system upon exposure to antigens and is long-lasting. Passive immunity is acquired by receiving ready-made antibodies from an external source and provides immediate, temporary protection.
How does HIV replicate inside the human body?
HIV is a retrovirus. Once it enters a helper T-cell, its RNA genome is reverse-transcribed into viral DNA by the enzyme reverse transcriptase. This viral DNA incorporates into the host cell's DNA, directing the production of new viral particles.
What are oncogenes?
Oncogenes are genes that have the potential to cause cancer. In normal cells, they exist as proto-oncogenes which regulate cell growth, but mutations or viral activation can turn them into cancer-causing oncogenes.
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