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NCERT Solutions Class 12 Biology Chapter 7 Human Health and Disease
Students of Class 12 Biology Chapter 7 Human Health and Disease learn about how the body remains healthy and what different factors cause sickness. In this chapter we describe common infectious and non-infectious diseases, their causes, symptoms and ways of preventing them. It also covers the immune system, types of immunity and the role of vaccines in protecting the body. This helps students understand how the body defends itself against harmful organisms and conditions.
ALLEN helps you to master these concepts by providing high quality NCERT Solutions which converts complicated theory into clear logical lessons. Our subject matter experts are committed to simplifying complex life cycles and pathways into easy to remember, step-by-step explanations. These solutions are tailored to help you meet the criteria of the CBSE marking scheme, and ensure you can confidently reproduce accurate diagrams and technical terms during the exams.
1.0Key Concepts of Class 12 Biology Chapter 7 Human Health and Disease
This chapter covers important aspects of human health, including infectious and non-infectious diseases, immunity, vaccination, and disease prevention. The main concepts include:
- Health and Disease: Understand the meaning of health and learn about the physical, mental, and social factors that influence overall well-being.
- Pathogens and Infectious Diseases: Study disease-causing organisms such as bacteria, viruses, fungi, protozoans, and worms, along with the diseases they cause.
- Non-Infectious Diseases: Learn about conditions such as cancer, allergies, and lifestyle-related disorders, including their causes and effects on the body.
- Immune System: Understand innate and acquired immunity and how different components of the immune system protect the body from infections.
- Vaccination and Immunisation: Learn how vaccines stimulate the body's immune response and help provide protection against specific infectious diseases.
- Antibiotics and Drug Resistance: Understand the role of antibiotics in treating bacterial infections and learn why improper use can contribute to antibiotic resistance.
- Public Health Measures: Study the importance of personal hygiene, sanitation, clean drinking water, proper waste disposal, and other measures used to prevent the spread of diseases.
2.0NCERT Class 12 Biology Chapter 7 Human Health and Disease : Detailed Solutions
- What are the various public health measures, which you would suggest as safeguard against infectious diseases? Ans. Few of the public health measures as safeguard against infectious diseases are :
- Proper disposal of waste and excreta
- Periodic cleaning and disinfection of water reservoirs, pools, cesspools and tanks
- Observing standard practices of hygiene in public catering
- In which way has the study of biology helped us to control infectious diseases? Ans. The advancements made in biological science have armed us to effectively deal with many infectious diseases.
- The use of vaccines and immunisation programmes have enabled us to completely eradicate a deadly disease like smallpox and to control other infectious diseases like polio, diphtheria, pneumonia and tetanus to a large extent.
- Biotechnology is at the verge of making available newer and safer vaccines.
- Discovery of antibiotics and various other drugs has also enabled us to effectively treat infectious diseases.
- How does the transmission of each of the following diseases take place? [IMP.] (a) Amoebiasis (b) Malaria (c) Ascariasis (d) Pneumonia
Ans.
(a) Amoebiasis:- Houseflies act as mechanical carriers and serve to transmit the pathogen (Entamoeba histolytica) from faeces of infected person to food and food products, thereby contaminating them. Drinking water and food contaminated by the faecal matter are the main source of infection. (b) Malaria :- Malaria is transmitted to a healthy person with the bite of an infected female Anopheles mosquito. The female Anopheles mosquito is the vector (transmitting agent) for the pathogen (Plasmodium). (c) Ascariasis:- The eggs of the pathogen (Ascaris) are excreted along with the faeces of infected persons which contaminate soil, water, plants, etc. A healthy person acquires this infection through contaminated water, vegetables, fruits, etc. (d) Pneumonia :- A healthy person acquires the infection by inhaling the droplets/aerosol released by an infected person or even by sharing glasses and utensils with an infected person.
- What measure would you take to prevent water-borne diseases?
Ans. Measures particularly essential to prevent water-borne diseases are:
(1) Maintenance of personal hygiene by :
- Keeping the body clean
- Consumption of clean drinking water, food, vegetables, fruits, etc
(2) Maintenance of public hygiene by :
- Proper disposal of waste and excreta
- Periodic cleaning and disinfection of water reservoirs, pools, cesspools and tanks
- Observing standard practices of hygiene in public catering
- Discuss with your teacher what does 'a suitable gene' means, in the context of DNA vaccines.
Ans. 'A suitable gene' means that a disease-resistant gene present on the genome of lower organisms. By the technique of genetic engineering, this 'suitable gene' is transferred in a vaccine to inject in human beings to induce the development of immunity.
- Name the primary and secondary lymphoid organs. [IMP.] Ans. Primary lymphoid organs - Bone Marrow, Thymus gland. Secondary lymphoid organs - Spleen, Lymph nodes, Tonsils, Peyer's patches of small intestine, Appendix.
- The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form: [IMP.] (a) MALT (b) CMI (c) AIDS (d) NACO (e) HIV Ans.
(a) MALT = Mucosa Associated Lymphoid Tissue (b) CMI = Cell Mediated Immunity (c) AIDS = Acquired Immuno Deficiency Syndrome (d) NACO = National AIDS Control Organisation (e) HIV = Human Immunodeficiency Virus
- Differentiate the following and give examples of each: (a) Innate and acquired immunity (b) Active and passive immunity
Ans.
(a) Difference between innate and acquired immunity :
(b) Difference between active and passive immunity :
- Draw a well-labelled diagram of an antibody molecule. [IMP.] Ans.
- What are the various routes by which transmission of human immuno - deficiency virus takes place? Ans. Transmission of HIV-infection generally occurs :
- By sexual contact with infected person
- By transfusion of contaminated blood and blood products
- By sharing infected needles as in the case of intravenous drug abusers
- From infected mother to her child through placenta
- What is the mechanism by which the AIDS virus causes deficiency of immune system of the infected person? Ans. HIV enters into helper T-lymphocytes and produce progeny viruses. The progeny viruses released in the blood attack other helper T-lymphocytes. This is repeated leading to a progressive decrease in the number of helper T-lymphocytes in the body of the infected person. Due to progressive decrease in the number of helper T-lymphocytes, the person becomes immuno-deficient.
- How is a cancerous cell different from a normal cell? Ans. Unlike a normal cell,
- Cancerous cell undergoes uncontrolled mitotic divisions.
- Cancerous cell leads to the formation of tumour.
- Cancerous cell does not show contact inhibition.
- Explain what is meant by metastasis. Ans. Cells sloughed from such tumors reach distant sites through blood and wherever they get lodged in the body & they start a new tumor there. This property called metastasis is the most feared property of malignant tumors.
- List the harmful effects caused by alcohol/drug abuse. Ans. Few of the harmful effects caused by alcohol/drug abuse are :
- Immediate adverse effects of drugs and alcohol abuse are reckless behavior, vandalism, violence etc.
- Excessive doses of drugs may lead to coma, death due to respiratory failure, heart failure or cerebral haemorrhage.
- A combination of drugs or their intake along with alcohol generally results in overdosing and even deaths.
- The chronic use of drugs and alcohol damages nervous system and liver (cirrhosis).
- The use of drugs and alcohol during pregnancy is also known to adversely affect the foetus.
- Do you think that friends can influence one to take alcohol/drugs? If yes, how may one protect himself/herself from such an influence? Ans. One of the reasons for alcohol drinking or drug abuse is peer pressure, so one can be easily influenced by one's friends to take alcohol /drugs. One must avoid undue peer pressure with one's own will-power or may seek the help of one's parents and teachers.
- Why is that once a person starts taking alcohol or drugs, it is difficult to get rid of this habit? Discuss it with your teacher. Ans. Use of alcohol or drugs even once can be a fore-runner to addiction. Thus, the addictive potential of drugs and alcohol, pull the user into a vicious circle leading to their regular use (abuse) from which the person may not be able to get out. In the absence of any guidance or counseling, the person gets addicted and becomes dependent on their use. Dependence is the tendency of the body to manifest a characteristic and unpleasant withdrawal syndrome if regular dose of drugs/alcohol is abruptly discontinued. This is characterised by anxiety, shakiness, nausea and sweating, which may be relieved when use is resumed again. In some cases, withdrawal symptoms can be severe and even life threatening and the person may need medical supervision.
- In your view what motivates youngsters to take to alcohol or drugs and how can this be avoided? [IMP.] Ans. Causes for motivation among youngsters towards alcohol or drugs use include :
- Natural curiosity
- Need for adventure and excitement
- Experimentation
- Perception that it is 'cool' or progressive to smoke use drugs or alcohol
- To escape facing problems (like stress, from pressures to excel in academics or examinations)
- Unstable or unsupportive family structures and peer pressure
And measures particularly useful to avoid alcohol or drugs abuse among youngsters include:
- Avoid undue peer pressure
- Education and counseling
- Seeking help from parents and peers
- Looking for danger signs
- Seeking professional and medical help
3.0NCERT Solutions for Class 12 Biology | Other Chapter-wise Links
Find Class 12 Biology NCERT Solutions chapter-wise with detailed answers, simple explanations, and complete coverage of textbook questions using the links below.
4.0Key Features and Benefits of Class 12 Biology Chapter 7 Human Health and Disease
- Understanding Diseases and Their Causes: Learn how infectious diseases develop, how pathogens affect the human body, and how common diseases can be prevented.
- Immunity Made Easier: Understand innate and acquired immunity, immune responses, antibodies, vaccines, and the body's defence mechanisms through clear explanations.
- Disease-Based Practice: Practise NCERT questions related to diseases, immunity, allergies, AIDS, cancer, and other important topics covered in the chapter.
- Quick and Effective Revision: Revise important medical terms, disease-causing organisms, symptoms, prevention methods, and health-related concepts for better recall.
- Strong Foundation for NEET: Strengthen your understanding of human health and disease concepts that are important for NEET and other biology-based competitive examinations.