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NCERT Solutions for Class 12 Biology Chapter 7 Human Health and Disease
Edited By Irshad Anwar | Updated on Jun 20, 2025 11:55 AM IST | #CBSE Class 12th
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The NCERT Solutions for Class 12 Biology Chapter 7 Human Health and Disease discusses various forms of immunity, such as innate and acquired immunity, and how the immune system fights infections. Common diseases such as bacterial, viral, fungal, and protozoan infections, including their causes, symptoms, and prevention, and lifestyle diseases like cancer, drug addiction, and mental illness are also covered. The NCERT Solutions present the topics in a clear and organised way, making it easier for students to understand them.
This Story also Contains
- Download PDF of NCERT Solutions For Class 12 Biology Chapter 7
- NCERT Solutions for Class 12 Biology Chapter 7 (Exercise Questions)
- Approach to Solve Questions of Class 12 Chapter 7
- Important Question of Class 12 Biology Chapter 7
- What Extra Should Students Study Beyond the NCERT for NEET?
- NCERT Solutions for Class 12 Biology Chapter-wise
Through the proper study of the NCERT Solutions for Class 12, students are able to achieve a strong foundation in the subject of biology, which is important for achieving academic success as well as a successful career in the health sciences field. This chapter is also important for NEET preparation, as it covers key topics that are frequently asked in competitive medical entrance exams. The NCERT Solutions for Class 12 Biology provide explanations of all the questions in a step-by-step, detailed manner so that students can easily understand the topics and concepts without any further help.
Also Read,
NCERT Exemplar for Class 12 Biology Human Health and Disease
Download PDF of NCERT Solutions For Class 12 Biology Chapter 7
Students can download the complete questions with detailed answers in a PDF of Human Health and Disease chapter for better learning:
NCERT Solutions for Class 12 Biology Chapter 7 (Exercise Questions)
The detailed answers to all the questions of Human Health and Disease chapter are given below:
Answer:
To avoid infectious diseases, the following public health measures can be implemented:
- Vaccination: Individuals should get vaccinated on time to prevent diseases such as cholera, tuberculosis, and hepatitis.
- Awareness: All should be informed about diseases to safeguard themselves.
- Sanitation: Maintaining the environment clean, consuming clean water, and having hygienic food can prevent diseases.
- Vector Control: The disease-carrying insects and pests must be eradicated by destroying their breeding grounds.
Ques 2. In which way has the study of biology helped us to control infectious diseases?
Answer:
The study of biology has contributed greatly to the prevention of diseases in various ways:
- It makes us aware of the cause of diseases.
- It helps in recognising how diseases are transmitted, e.g., if an individual develops diarrhoea, the infection can spread through dirty food or water.
- It helps in discovering medicine for treating infected individuals.
- It helps in the formulation of vaccines for preventing diseases
Ques 3. How does the transmission of each of the following diseases take place?
A) Amoebiasis
Answer:
Amoebiasis - It is transmitted through the consumption of water and food contaminated by amoebic cysts.
B) Malaria
Answer:
Malaria - It is transmitted from one person to another using the female Anopheles mosquito. When this mosquito bites a diseased person, along with blood, it takes the parasite along with blood, and when biting a healthy person, the parasite transfers to the healthy person.
C) Ascariasis
Answer:
Ascariasis - It is transmitted through food and water contaminated with eggs of the parasite.
D) Pneumonia
Answer:
Pneumonia - It transmits through droplet infection, i.e., through a sneeze, cough, sharing utensils, etc.
Ques 4. What measures would you take to prevent water-borne diseases?
Answer:
Waterborne diseases such as typhoid and cholera are prevented by:
- Proper disposal of sewage and waste.
- Periodic inspection and purification of water sources.
- Only purified and clean water.
Ques 5. Discuss with your teacher what 'a suitable gene' means in the context of DNA vaccines.
Answer:
A suitable gene is a unique segment of DNA that is implanted in the body to make certain proteins. These proteins protect the body against dangerous disease-producing organisms.
Ques 6. Name the primary and secondary lymphoid organs.
Answer:
Lymphoid organs help in making and activating immune cells:
- Primary lymphoid organs: These are the bone marrow and thymus, where immune cells mature.
- Secondary lymphoid organs: These are the spleen, lymph nodes, tonsils, Peyer's patches in the intestine, and the appendix, where immune cells encounter infections.
Ques7: The following are some well-known abbreviations, which have been used in this chapter. Expand well-known abbreviations
a) MALT
Answer:
MALT- Mucosal Associated Lymphoid Tissue
b) CMI
Answer:
CMI - Cell Mediated Immunity
c) AIDSAnswer:
AIDS- Acquired Immune Deficiency Syndrome
d) NACOAnswer:
NACO- National AIDS Control Organisation
e) HIVAnswer:
HIV- Human Immunodeficiency Virus
Ques8: Differentiate the following and give examples of each:
(a) Innate and acquired immunity
Answer:
Innate Immunity | Acquired Immunity |
| Present from birth and provides general protection. | Develops when the body is exposed to specific infections. |
| Lasts for a lifetime. | Temporary and specific to the disease. |
| Passed down genetically. | Not inherited from parents. |
(b) Active and passive immunity
Answer:
Active Immunity | Passive Immunity |
| The body produces its antibodies after infection or vaccination. | Antibodies are given from an external source (e.g., injection). |
| Long-lasting protection. | Short-term protection. |
| Takes time to develop. | Works immediately. |
Ques 9. Draw a well-labeled diagram of an antibody molecule.
Answer:
The well-labelled diagram of an antibody molecule is as follows:
Ques 10. What are the various routes by which transmission of human immunodeficiency virus takes place?
Answer:
HIV is transmitted in various ways:
- By sharing contaminated needles.
- Through unprotected sex with an infected individual.
- From an infected mother to her child during pregnancy.
- By receiving contaminated blood during a transfusion.
Answer:
HIV causes a deficiency of the immune system in the following ways:
- It binds to helper T-cells and injects its genetic material.
- It utilises the machinery of the cell to make more copies of itself.
- The infected T-cells burst, spilling more virus particles.
- With time, the T-cells reduce in number, weakening the body against infections.
Ques 12. How is a cancerous cell different from a normal cell?
Answer:
Differences between cancerous cells and normal cells
Cancerous Cells | Normal Cells |
| Divide uncontrollably, forming tumours | Grow and divide at a normal rate |
| Can spread to other tissues and organs | Stay in one place and perform normal functions |
Ques 13. Explain what is meant by metastasis.
Answer:
Metastasis is the condition when the cancer cells move from the primary location to other locations of the body through the blood or lymph. It is the terminal stage of cancer.
Ques 14. List the harmful effects caused by alcohol/drug abuse.
Answer:
Drug and alcohol abuse result in:
Ques 15. Do you think that friends can influence one to take alcohol/drugs? If yes, how may one protect himself/herself from such an influence?
Answer:
Yes, peer pressure can result in drug or alcohol consumption. It can be prevented by:
- Avoid individuals who consume drugs or alcohol.
- Developing self-discipline and willpower.
- Learning about the dangerous impacts of addiction.
- Seeking support from parents or teachers.
- Seeking proper medical assistance should depression or emotional distress become present.
Ques16. In your view, what motivates youngsters to take to alcohol or drugs and how can this be avoided?
Answer:
Teenagers can begin consuming alcohol or drugs because of:
- Pressure from peers.
- Desire for thrill and curiosity.
- Stress, depression, or emotional issues.
- Media pressure, wherein films and celebrities glorify alcohol and drug consumption.
Prevention is achieved through:
- Speaking to youth about the risks of addiction.
- Open conversations with teachers and parents.
- Healthy stress management.
- Positive role models and activities.
Answer:
After a person begins to take drugs or alcohol, it is hard to quit because:
- The brain becomes habituated to the effects and longs for more.
- With time, the body is unable to function normally without it.
- Withdrawal symptoms such as anxiety, pain, and depression make quitting hard.
- The individual can be socially dependent on alcohol or drugs.
NCERT Solutions for Class 12- Subject-wise
- NCERT Solutions for Class 12 Maths
- NCERT Solutions for Class 12 Chemistry
- NCERT Solutions for Class 12 Physics
NEET Highest Scoring Chapters & Topics
Most Scoring concepts For NEET (Based On Previous Year Analysis)
Download EBookApproach to Solve Questions of Class 12 Chapter 7
- Students initially need to understand the difference between infectious and non-infectious diseases.
- Diseases like typhoid, pneumonia, common cold, malaria, amoebiasis, and ascariasis, along with their causes, symptoms, and prevention, should be studied in details with complete focus.
- Next step is to understand the concept of immunity, its types, role of vaccines, antibodies, and the immune system.
- Students can prepare short notes by highlighting the causes, symptoms, and harmful effects of different types of drugs, and how to prevent and control this drug abuse.
- Practice the previous year question paper, all varieties of questions, to get an understanding of the question pattern and allow you to gain confidence to score better marks in exam.
Also, check the NCERT Books and the NCERT Syllabus here:
Important Question of Class 12 Biology Chapter 7
The Human Health and Disease chapter helps students understand the causes of various diseases, how the body fights infections, and the importance of immunity.
Question: Haemozoin is a
A. precursor of haemoglobin
B. The toxin released from Streptococcus-infected cells
C. The toxin released from Plasmodium-infected cells
D. The toxin released from Haemophilus-infected cells
Answer: The correct answer is option (c), the toxin released from Plasmodium-infected cells
Explanation:
A dangerous byproduct generated by the parasite Plasmodium in malaria disease is haemozoin, which is a by-product of the ingestion of haemoglobin by the parasitic red cell.
NCERT Exemplar Class 12 Solutions
- NCERT Exemplar Class 12 Chemistry Solutions
- NCERT Exemplar Class 12 Mathematics Solutions
- NCERT Exemplar Class 12 Physics Solutions
- NCERT Exemplar Class 12 Biology Solutions
What Extra Should Students Study Beyond the NCERT for NEET?
For better NEET preparation, students can explore some extra topics beyond NCERT. The table below lists key areas to focus on.
NCERT Solutions for Class 12 Biology Chapter-wise
Below are the Chapter-wise solutions:
Frequently Asked Questions (FAQs)
1. What are the key topics covered in NCERT Class 12 Biology Chapter 7?
The key topics covered in NCERT Class 12 Biology Chapter 7 are different types of diseases, immunity, vaccines, and the role of the immune system in fighting infections. It also discusses AIDS, cancer, drug abuse, and public health measures.
2. Where can I find NCERT solutions for Class 12 Biology Chapter 7?
Students can download and access the NCERT solutions for Class 12 Biology Chapter 7 through the Careers360 page. The chapter-wise biology class 12 solution can be downloaded through https://school.careers360.com/ncert/ncert-solutions-class-12-biology
3. What is the difference between innate and acquired immunity?
| Innate Immunity | Acquired Immunity |
| Natural defence is present from birth. | Immunity develops over time after infections or vaccinations. |
| Non-specific, works against a wide range of pathogens. | Specific to a particular pathogen. |
| Memory does not improve with repeated exposure. | Has memory, and provides stronger protection on re-exposure. |
| Immediate response. | Takes time to develop after infection or vaccination. |
| Skin, mucus, white blood cells, stomach acid. | Antibodies, vaccines, memory cells. |
4. How do vaccines help in disease prevention?
Vaccines are made of weakened or dead disease-causing germs. When they are put into the body, they make the immune system produce antibodies. This makes the body able to recognise and attack the infection in the future.
5. What are the different types of immunity explained in NCERT Chapter 7?
The chapter Human Health and Disease explains two types of immunity:
- Innate Immunity – Natural immunity from birth.
- Acquired Immunity – Gained over a period of time due to infection or vaccines.
6. What are the common diseases mentioned in Class 12 Biology Chapter 7?
The class 12 chapter Human Health and Disease explains different diseases, such as bacterial, viral, protozoal, and fungal. A few of them are malaria, pneumonia, amoebiasis, typhoid, dengue, and HIV/AIDS.
7. How does the immune system fight infections?
The immune system makes white blood cells and antibodies to fight and kill dangerous microorganisms. It also contains memory cells that enable it to recognise and combat the same infection if it re-enters the body.
8. What are the causes and symptoms of AIDS?
AIDS results from the HIV virus, which affects the immune system. The symptoms include weight loss, fever, tiredness, recurring infections, and inflamed lymph nodes.
9. What is the role of interferons in immunity?
Interferons are proteins that are released from cells as a response to viral infections. They protect surrounding cells from the virus and improve the immune system's response.
10. How do antibiotics and antiviral drugs work against infections?
- Antibiotics kill or inhibit bacteria but have no effect on viruses.
- Antiviral medications help in slowing down or preventing the viruses from replicating within the body.
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16 min ⋆ Jun 07, 2025 06:06 AM ISTQuestions related to CBSE Class 12th
Have a question related to CBSE Class 12th ?
Changing from the CBSE board to the Odisha CHSE in Class 12 is generally difficult and often not ideal due to differences in syllabi and examination structures. Most boards, including Odisha CHSE , do not recommend switching in the final year of schooling. It is crucial to consult both CBSE and Odisha CHSE authorities for specific policies, but making such a change earlier is advisable to prevent academic complications.
Manasvini Gupta 30 January,2025
Hello there! Thanks for reaching out to us at Careers360.
Ah, you're looking for CBSE quarterly question papers for mathematics, right? Those can be super helpful for exam prep.
Unfortunately, CBSE doesn't officially release quarterly papers - they mainly put out sample papers and previous years' board exam papers. But don't worry, there are still some good options to help you practice!
Have you checked out the CBSE sample papers on their official website? Those are usually pretty close to the actual exam format. You could also look into previous years' board exam papers - they're great for getting a feel for the types of questions that might come up.
If you're after more practice material, some textbook publishers release their own mock papers which can be useful too.
Let me know if you need any other tips for your math prep. Good luck with your studies!
Jefferson 25 September,2024
It's understandable to feel disheartened after facing a compartment exam, especially when you've invested significant effort. However, it's important to remember that setbacks are a part of life, and they can be opportunities for growth.
Possible steps:
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Re-evaluate Your Study Strategies:
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-
Consider Professional Help:
- Tutoring: A tutor can provide personalized guidance and support.
- Counseling: If you're feeling overwhelmed or unsure about your path, counseling can help.
-
Explore Alternative Options:
- Retake the Exam: If you're confident in your ability to improve, consider retaking the chemistry compartment exam.
- Change Course: If you're not interested in pursuing chemistry further, explore other academic options that align with your interests.
-
Focus on NEET 2025 Preparation:
- Stay Dedicated: Continue your NEET preparation with renewed determination.
- Utilize Resources: Make use of study materials, online courses, and mock tests.
-
Seek Support:
- Talk to Friends and Family: Sharing your feelings can provide comfort and encouragement.
- Join Study Groups: Collaborating with peers can create a supportive learning environment.
Remember: This is a temporary setback. With the right approach and perseverance, you can overcome this challenge and achieve your goals.
I hope this information helps you.
Kanishka kaushikii 17 September,2024
Hi,
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Yuvan 30 August,2024
hello mahima,
If you have uploaded screenshot of your 12th board result taken from CBSE official website,there won,t be a problem with that.If the screenshot that you have uploaded is clear and legible. It should display your name, roll number, marks obtained, and any other relevant details in a readable forma.ALSO, the screenshot clearly show it is from the official CBSE results portal.
hope this helps.
Ashvadha 12 July,2024
Popular CBSE Class 12th Questions
A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is
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Option 2)
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Option 4)
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An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range
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A particle is projected at 600 to the horizontal with a kinetic energy . The kinetic energy at the highest point
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In the reaction,
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How many moles of magnesium phosphate, will contain 0.25 mole of oxygen atoms?
| Option 1)
0.02 |
Option 2)
3.125 × 10-2 |
| Option 3)
1.25 × 10-2 |
Option 4)
2.5 × 10-2 |
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