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NCERT Solutions for Class 12 Biology Chapter 7 Human Health and Disease

NCERT Solutions for Class 12 Biology Chapter 7 Human Health and Disease

#CBSE Class 12th
author
Irshad AnwarUpdated on 14 Aug 2025, 12:04 PM IST

The NCERT Solutions for Class 12 Biology Chapter 7 Human Health and Disease discusses various forms of immunity. It includes innate and acquired immunity and how the immune system fights infections. Common diseases such as bacterial, viral, and fungal, and lifestyle diseases like cancer and drug addiction, are covered. The NCERT Solutions present the topics in a clear and organised way. This makes it easier for students to understand the concepts and score well in exams.

This Story also Contains

  1. Download PDF of NCERT Solutions For Class 12 Biology Chapter 7
  2. Get Class 12 Biology Chapter 7 Solutions (Exercise Questions)
  3. Approach to Solve Class 12 Biology Chapter 7 Question Answer
  4. Important Question from Class 12 Biology Chapter 7 Solutions
  5. What Extra Should Students Study Beyond the NCERT for NEET?
  6. NCERT Solutions for Class 12 Biology Chapter-wise
NCERT Solutions for Class 12 Biology Chapter 7 Human Health and Disease
NCERT Solutions for Class 12 Biology Chapter 7 Human Health and Disease

Through the study of the Class 12 Biology Chapter 7 Solutions, students are able to understand diseases and how to protect themselves. This chapter is also important for NEET preparation, as it covers topics that are frequently asked in exams. The NCERT Solutions for Class 12 Biology provide explanations of all the questions in a step-by-step manner. For quick and easy revision, students can download the Human Health and Disease Class 12 NCERT Solutions PDF.

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 PDF of the Human Health and Disease chapter from the link given below. This PDF includes answers of all the questions in a well-understandable manner.

Download PDF

Get Class 12 Biology Chapter 7 Solutions (Exercise Questions)

The detailed answers to all the questions of this chapter are given below. By going through the Class 12 Biology Chapter 7 question answer, students can gain knowledge about diseases. It includes how do different diseases spread, and what measures we can take to protect ourselves.

Ques1. What are the various public health measures which you would suggest as a safeguard against infectious diseases?

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) AIDS

Answer:

AIDS- Acquired Immune Deficiency Syndrome

d) NACO

Answer:

NACO- National AIDS Control Organisation

e) HIV

Answer:

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.
Acts as the first line of defenceActs as the second line of defence
Passed down genetically.Not inherited from parents.

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:

antibody

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.

Ques 11. What is the mechanism by which the AIDS virus causes a deficiency of the immune system of the infected person?

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 tumoursGrow and divide at a normal rate
Can spread to other tissues and organsStay 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:

  • Weakening of body tissues and organs.
  • Heart issues are due to damage to the blood vessels.
  • Liver ailments such as cirrhosis.
  • Kidney failure due to overwork.
  • Infertility and other reproductive issues.
  • Damage to social life and family.
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.

Ques 17. Why is it that once a person starts taking alcohol or drugs, it is difficult to get rid of this habit? Discuss it with your teacher.

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

NEET Highest Scoring Chapters & Topics
Most Scoring concepts For NEET (Based On Previous Year Analysis)
Download EBook

Approach to Solve Class 12 Biology Chapter 7 Question Answer

Below are a few steps that students can follow to solve the questions from this chapter easily.

  • Students first need to understand the difference between infectious and non-infectious diseases.

  • Different diseases like typhoid, pneumonia, malaria, and ascariasis should be studied in detail. Students can create flashcards by using the NCERT Solutions for Class 12 Biology Chapter 7, Human Health and Disease.

  • The next step is to understand the concept of immunity, its types, antibodies, and the immune system. For a detailed explanation, students can use the Human Health and Disease Class 12 NCERT Solutions PDF.

  • Students can prepare short notes by highlighting the symptoms and effects of different drugs, and how to control drug abuse.

  • Practice all types of questions given in the NCERT Solutions for Class 12 to understand the question pattern.

Also, check the NCERT Books and the NCERT Syllabus here:

Recommended eBooks

Related eBooks & Sample Papers

Important Question from Class 12 Biology Chapter 7 Solutions

The Human Health and Disease chapter helps students understand the causes of diseases and the importance of immunity. Given below is an important question from this chapter. For more such questions, students can refer to the Human Health and Disease Class 12 NCERT Solutions. This improves their problem-solving skills and makes them familiar with the question pattern.

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

CBSE Class 12th Syllabus: Subjects & Chapters
Select your preferred subject to view the chapters

What Extra Should Students Study Beyond the NCERT for NEET?

For better NEET preparation, students can explore some extra topics beyond the NCERT. The table below lists key areas to focus on. Along with this, students can refer to the Human Health and Disease Class 12 NCERT Solutions to avoid confusion.

ConceptsNCERTNEET
Concept of Health & Diseases✅✅
Viral Diseases✅✅
Bacterial Diseases✅✅
Protozoan Disease✅✅
Life Cycle of Plasmodium✅✅
Diseases caused by Nematodes✅✅
Fungal Diseases✅✅
Immunity & Its Types✅✅
Innate Immunity✅✅
Characteristics of Acquired Immunity✅✅
Humoral Immunity or Antibody Mediated Immune System (AMIS)✅✅
Cell-Mediated Immune System✅✅
Types of Acquired Immunity✅✅
Immune Response & Lines of Defence✅✅
Antigens✅✅
Antibodies✅✅
Immune System in Humans✅✅
Vaccination & Immunisation✅✅
Disorders of the Immune System✅✅
AIDS✅✅
Cancer-I✅✅
Cancer-II✅✅
Commonly Abused Drugs✅✅
Addiction & Dependence✅✅
Effects of Drugs/Alcohol Abuse✅✅

NCERT Solutions for Class 12 Biology Chapter-wise

Below are the Chapter-wise solutions:

NCERT solutions for class 12 biology chapter 1 Sexual Reproduction in Flowering Plants

NCERT solutions for class 12 biology chapter 2 Human Reproduction

NCERT solutions for class 12 biology chapter 3 Reproductive Health

NCERT solutions for class 12 biology chapter 4 Principles of Inheritance and Variation

NCERT solutions for class 12 biology chapter 5 Molecular basis of inheritance

NCERT solutions for class 12 biology chapter 6 Evolution

NCERT solutions for class 12 biology chapter 7 Human health and disease

NCERT solutions for class 12 biology chapter 8 Microbes in Human Welfare

NCERT Solutions for class 12 Biology Chapter 9 Biotechnology: Principles and Processes

NCERT Solutions for Class 12 Biology Chapter 10 Biotechnology and its Application

NCERT Solutions for Class 12 Biology Chapter 11 Organisms and Populations

NCERT Solutions for Class 12 Biology Chapter 12 Ecosystem

NCERT Solutions for Class 12 Biology Chapter 13 Biodiversity and Conservation


Frequently Asked Questions (FAQs)

Q: What are the key topics covered in NCERT Class 12 Biology Chapter 7?
A:

The important topics covered in the NCERT Solutions for Class 12 Biology Chapter 7 Human Health and Disease 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.

Q: Where can I find NCERT solutions for Class 12 Biology Chapter 7?
A:

Students can download the NCERT Solutions for Class 12 Biology Chapter 7 Human Health and Disease through the Careers360 page, which is

https://school.careers360.com/ncert/ncert-solutions-class-12-biology-chapter-7 

Q: How do vaccines help in disease prevention?
A:

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. Students can refer to the Class 12 Biology Chapter 7 question answer, for more detailed explanation. 

Q: What are the common diseases mentioned in Class 12 Biology Chapter 7?
A:

The Human Health and Disease Class 12 NCERT Solutions explains different diseases, such as bacterial, viral, protozoal, and fungal. A few of them are malaria, pneumonia, amoebiasis, typhoid, dengue, and HIV/AIDS.

Q: How does the immune system fight infections?
A:

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.

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Questions related to CBSE Class 12th

On Question asked by student community

Have a question related to CBSE Class 12th ?
Can i improve my 12 result this year in PCM

Hello,

If you want to improve the Class 12 PCM results, you can appear in the improvement exam. This exam will help you to retake one or more subjects to achieve a better score. You should check the official website for details and the deadline of this exam.

I hope it will clear your query!!

Read Complete Answer
R
Rahul Mandal
8 Sep'25
what will be tha CBSE Exam Date?

For the 2025-2026 academic session, the CBSE plans to conduct board exams from 17 February 2026 to 20 May 2026.

You can download it in pdf form from below link

CBSE DATE SHEET 2026

all the best for your exam!!

Read Complete Answer
A
Afreen
13 Sep'25
registration no. 12th class cbse

Hii neeraj!

You can check CBSE class 12th registration number in:

  • Your class 12th board exam admit card. Please do check admit card for registration number, it must be there.
  • You can also check the registration number in your class 12th marksheet in case you have got it.
  • Alternatively you can also visit your school and ask for the same in the administration office they may tell you the registration number.

Hope it helps!

Read Complete Answer
S
Shivani Chaurasia
15 Sep'25
how may marks should i get in my 12th board exams to get fee concesion in sastra university

Hello Aspirant,

SASTRA University commonly provides concessions and scholarships based on merit in class 12 board exams and JEE Main purposes with regard to board merit you need above 95% in PCM (or on aggregate) to get bigger concessions, usually if you scored 90% and above you may get partial concessions. I suppose the exact cut offs may change yearly on application rates too.

Read Complete Answer
G
gopi
4 Sep'25
Which course is best for computer science students after 12th standard

Hello,

After 12th, if you are interested in computer science, the best courses are:

  • B.Tech in Computer Science Engineering (CSE) – most popular choice.

  • BCA (Bachelor of Computer Applications) – good for software and IT jobs.

  • B.Sc. Computer Science / IT – good for higher studies and research.

  • B.Tech in Information Technology (IT) – focuses on IT and networking.

All these courses have good career scope. Choose based on your interest in coding, software, hardware, or IT field.

Hope it helps !

Read Complete Answer
P
Prachi Kumari
4 Sep'25
View all

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

Option 1)

0.34\; J

 Option 2)

0.16\; J
Option 3)

1.00\; J

 Option 4)

0.67\; J
Read Complete Answer

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times.  Assume that the potential energy lost each time he lowers the mass is dissipated.  How much fat will he use up considering the work done only when the weight is lifted up ?  Fat supplies 3.8×107 J of energy per kg which is converted to mechanical energy with a 20% efficiency rate.  Take g = 9.8 ms−2 :

Option 1)

2.45×10−3 kg

 Option 2)

 6.45×10−3 kg
Option 3)

 9.89×10−3 kg

 Option 4)

12.89×10−3 kg

 
Read Complete Answer

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

Option 1)

2,000 \; J - 5,000\; J

 Option 2)

200 \, \, J - 500 \, \, J
Option 3)

2\times 10^{5}J-3\times 10^{5}J

 Option 4)

20,000 \, \, J - 50,000 \, \, J
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A particle is projected at 600   to the horizontal with a kinetic energy K. The kinetic energy at the highest point

Option 1)

K/2\,

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\; K\;
Option 3)

zero\;

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K/4
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In the reaction,

2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}

Option 1)

11.2\, L\, H_{2(g)}  at STP  is produced for every mole HCL_{(aq)}  consumed

 Option 2)

6L\, HCl_{(aq)}  is consumed for ever 3L\, H_{2(g)}      produced
Option 3)

33.6 L\, H_{2(g)} is produced regardless of temperature and pressure for every mole Al that reacts

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67.2\, L\, H_{2(g)} at STP is produced for every mole Al that reacts .
Read Complete Answer

How many moles of magnesium phosphate, Mg_{3}(PO_{4})_{2} 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
Read Complete Answer

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1)

decrease twice

 Option 2)

increase two fold
Option 3)

remain unchanged

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be a function of the molecular mass of the substance.
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With increase of temperature, which of these changes?

Option 1)

Molality

 Option 2)

Weight fraction of solute
Option 3)

Fraction of solute present in water

 Option 4)

Mole fraction.
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Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol-1) is

Option 1)

twice that in 60 g carbon

 Option 2)

6.023 × 1022
Option 3)

half that in 8 g He

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558.5 × 6.023 × 1023
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A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t2) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m2 , the number of rotations made by the pulley before its direction of motion if reversed, is

Option 1)

less than 3

 Option 2)

more than 3 but less than 6
Option 3)

more than 6 but less than 9

 Option 4)

more than 9
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