NCERT Solutions Class 8 Science Chapter 03 Health The Ultimate Treasure

Question 1. Group the diseases shown in the images as communicable or non-communicable.
Answer: Diseases that spread from one person to another are called communicable diseases. From the images shown, cold and flu, typhoid, and chickenpox fall into this group. On the other hand, diseases that do not spread from person to person and are caused by lifestyle, environment, or body conditions are known as non-communicable diseases. Diabetes and asthma belong to this category. In total, there are 3 communicable diseases and 2 non-communicable diseases.
In simple words: Some diseases pass from sick people to healthy people - these are communicable diseases. Other diseases do not spread but happen because of how we live or our body's condition - these are non-communicable diseases.

Exam Tip: Always remember that communicable diseases have a pathogen (virus or bacteria) that spreads; non-communicable diseases are linked to lifestyle, genetics, or environment and cannot be caught from others.

Question 2. Diseases can be broadly grouped into communicable and non-communicable diseases. From the options given below, identify the non-communicable diseases.
(i) Typhoid
(ii) Asthma
(iii) Diabetes
(iv) Measles
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (ii) and (iv)
Answer: (b) (ii) and (iii)
In simple words: Asthma happens when someone's breathing tubes get narrow - it does not spread. Diabetes occurs when the body cannot manage sugar properly - it also does not spread. Both are non-communicable.

Exam Tip: Typhoid comes from contaminated food or water (communicable). Measles spreads through the air when infected people cough or sneeze (communicable). Only diseases without a spreading pathogen are non-communicable.

Question 3. There is a flu outbreak in your school. Several classmates are absent, while some are still coming to school coughing and sneezing.
(i) What immediate actions should the school take to prevent further spread?
Answer: The school should tell students who are ill to stay home and rest so they do not infect others. Teachers should remind all students to cover their mouth and nose when coughing or sneezing. The school must place hand sanitizers and soap in easily accessible areas and remind students to wash their hands regularly. Classrooms need to be kept clean and should have good air circulation. Finally, school authorities should inform parents about the outbreak and request their support in keeping sick children at home.
In simple words: Sick students should not come to school. Everyone should cover their cough. Keep hands clean. Keep the classroom clean and with fresh air.

Exam Tip: Examiners look for isolation of sick people, hygiene measures, and parent communication - all key public health steps during an outbreak.

Question 3. (ii) If your classmate, who shares the bench with you, starts showing symptoms of the flu, how can you respond in a considerate way without being rude or hurtful?
Answer: You should treat your classmate with kindness and respect. Do not laugh at them or say hurtful things. Speak to them gently and suggest they talk to a teacher about how they are feeling and ask for rest. You can offer them a tissue or politely remind them to cover their nose and mouth while coughing. These actions show that you care about their wellbeing while still being careful about their health.
In simple words: Be kind and do not tease them. Gently suggest they see a teacher. Help them by offering tissues.

Exam Tip: This question tests both health knowledge and social skills - show empathy and practical support without shaming or hurting your classmate's feelings.

Question 3. (iii) How can you protect yourself and others from getting infected in this situation?
Answer: Wash your hands with soap or a hand sanitizer after touching any surface. Wear a mask in the classroom to reduce the chance of breathing in infected droplets. Avoid touching your eyes, nose, or mouth without needing to. Keep some distance from people who are coughing or sneezing, but do this politely without making them feel isolated. Drink warm water, eat foods that are good for your health, and get enough sleep so your body's defenses stay strong.
In simple words: Wash your hands often. Wear a mask if you can. Stay a little away from sick people. Sleep well and eat healthy food.

Exam Tip: Focus on personal hygiene, physical barriers (mask and distance), and immune-boosting habits - these are the three main defense layers against flu spread.

Question 4. Your family is planning to travel to another city where malaria is prevalent.
(i) What precautions should you take before, during, and after the trip?
Answer: Before your trip, speak with a doctor and take their advice. Prepare by packing mosquito nets and repellent products, and bring clothes that cover your arms and legs. During your journey, use mosquito nets when you sleep, apply repellent on exposed areas of skin, make sure there is no stagnant water near where you stay, and keep wearing protective clothing. After you return home, watch carefully for any signs of fever, chills, or body pain. If any of these symptoms develop, see a doctor right away and get a blood test done.
In simple words: Before: Ask a doctor for advice and pack nets and repellent. During: Use nets at night and cover your skin. After: Watch for fever and see a doctor if you feel unwell.

Exam Tip: Include all three time phases - pre-travel preparation, active protection during stay, and post-travel monitoring - for a complete answer.

Question 4. (ii) How can you explain the importance of mosquito nets or repellents to your sibling?
Answer: I would explain to my sibling that mosquitoes carry malaria parasites. When these mosquitoes bite us, they pass the infection into our bloodstream. If we sleep without a net, mosquitoes can bite us very easily throughout the night. Nets and repellents work like a protective shield that keeps mosquitoes away from our skin. Think of it like wearing armor to defend yourself against an enemy - the net and repellent are your armor against disease-carrying mosquitoes.
In simple words: Mosquitoes give us malaria when they bite. A net stops them from biting you while you sleep. It is like a shield around you.

Exam Tip: Use simple, relatable language and analogies - comparing the net to armor or a shield makes the concept easy to understand for a younger sibling.

Question 4. (iii) What could happen if travellers ignore health advisories in such areas?
Answer: If travellers do not follow health guidance, they put themselves at serious risk. They may contract malaria, which causes fever, chills, and weakness that makes them very uncomfortable. This sickness can become so serious that they may need to stay in a hospital. In addition, they may bring the infection back to their home, putting their family members and others in their community at risk of catching the disease as well.
In simple words: You might get malaria and feel very sick. You might need to go to a hospital. You could give malaria to your family when you go home.

Exam Tip: Cover both personal consequences (sickness, hospitalization) and community spread - this shows understanding of disease transmission and public health impact.

Question 5. Your uncle has started smoking just to fit in with his friends, even though it is well known that smoking can seriously harm health and even cause death.
(i) What would you say to him to make him stop, without being rude?
Answer: I would speak to him with care and respect. I would say something like, "Uncle, I care a lot about you. I know smoking may seem appealing and cool, but it can damage your lungs, lead to cancer, and even shorten your life span. You are strong enough to say no to this kind of pressure from your friends. Your friends will actually respect you more if you choose your health over smoking."
In simple words: Tell him you care about him. Explain that smoking harms the lungs and can cause serious illness. Tell him real friends will respect him for saying no.

Exam Tip: Balance care with facts - show concern for his wellbeing while presenting clear health consequences, and emphasize that saying no shows strength, not weakness.

Question 5. (ii) What would you do if your friend offers you a cigarette at a party?
Answer: I would say a clear but polite "No, thanks." If I want to explain, I could add, "I do not want to damage my health. Let us enjoy the party in other ways." If they keep pushing me or refuse to accept my answer, I will walk away calmly without feeling ashamed, because true friends do not force you to do something that harms you.
In simple words: Say no politely. Explain you want to stay healthy. Walk away if they do not stop asking.

Exam Tip: Show assertiveness - a clear, polite refusal followed by firm action (walking away) - without being rude or judgmental toward your friend.

Question 5. (iii) How can schools help prevent students from indulging in such harmful habits?
Answer: Schools can run awareness programs that teach students about the dangers of smoking, alcohol, and drugs. Inviting doctors or counsellors to speak to students in assemblies makes the message more powerful and credible. Schools can show short films, display posters, and organize street plays that highlight the harmful effects of these substances in a way that stays in students' minds. Most importantly, schools should encourage students to take part in healthy activities like sports, yoga, and debate competitions. When students feel confident and busy with positive activities, they are much less likely to give in to pressure from friends to try harmful substances.
In simple words: Run programs about dangers of smoking. Invite doctors to talk. Show films and plays about it. Give students fun activities like sports and debates.

Exam Tip: Mention awareness-raising (talks, films, posters) AND positive alternatives (sports, yoga) - prevention works best when you inform AND provide better choices.

Question 6. Saniya claims to her friend Vinita that "Antibiotics can cure any infection, so we don't need to worry about diseases." What question(s) can Vinita ask her to help Saniya understand that her statement is incorrect?
Answer: Vinita can ask several important questions to challenge this claim. She could ask, "Do antibiotics work against viruses like the flu, cold, or measles?" She might also ask, "If antibiotics could cure every disease, then why do we still need vaccines?" Another good question would be, "Why do doctors tell us not to take antibiotics for coughs and colds?" Finally, Vinita could ask, "Have you heard about antibiotic resistance - when germs stop responding to medicines?" These questions will help Saniya think more carefully and come to understand that antibiotics only work against bacterial infections, not viral infections or other types of diseases.
In simple words: Ask her: Do antibiotics kill viruses? Then why do we need vaccines? Why do doctors say not to use them for colds? Do you know about antibiotic resistance?

Exam Tip: This question requires you to think critically - identify the key misconception and ask targeted questions that reveal its flaws, rather than just stating the correct information.

Question 7. The following table contains information about the number of dengue cases reported in a hospital over a period of one year. Make a bar graph of the number of cases on the Y-axis and the month on the X-axis. Critically analyse your findings and answer the following:

Question 7. (i) In which three months were the dengue cases highest?
Answer: The three months with the highest number of dengue cases are July, August, and September. Each of these months had 65 cases reported, which is the peak during the entire year.
In simple words: July, August, and September all had 65 cases each - the most of any months in the year.

Exam Tip: Always identify the exact months and the number for clarity - saying "peak months" alone is incomplete without naming them.

Question 7. (ii) In which month(s) were the cases lowest?
Answer: January recorded the lowest number of dengue cases in the year, with only 10 cases reported at that time.
In simple words: January had the fewest cases - only 10 people got dengue that month.

Exam Tip: Always state both the month name and the exact number to show you have read the data correctly.

Question 7. (iii) What natural or environmental factors during the peak months might contribute to the increase in dengue cases?
Answer: The months with the highest dengue cases - July, August, and September - fall during the monsoon or rainy season in many parts of India. During this season, rain collects in many places like puddles, tanks, buckets, and other containers. This stagnant water provides an ideal breeding ground for the Aedes aegypti mosquito, which transmits dengue. The warm, wet conditions during the monsoon help mosquito eggs hatch and larvae grow quickly, resulting in more mosquitoes and therefore more dengue infections.
In simple words: These months have heavy rain. Rain fills puddles and containers with water. Mosquitoes lay eggs in this standing water. More mosquitoes means more dengue.

Exam Tip: Connect the data pattern to seasonal changes and mosquito biology - show you understand the cause-and-effect relationship, not just observe the numbers.

Question 7. (iv) Suggest a few preventive steps that the community or government can take before the peak season to reduce the spread of dengue.
Answer: Communities and governments should take action before the monsoon arrives to lower dengue spread. Water tanks and storage containers should be cleaned thoroughly and then covered with lids to stop water from collecting. Authorities should carry out regular fogging and spraying of insecticides in public areas to kill adult mosquitoes. People should be encouraged to use mosquito nets, especially at night, and to apply mosquito repellents on their skin. Schools, neighborhoods, and markets should run awareness campaigns to teach people about dengue prevention. Communities should organize cleanliness drives to remove old tyres, plastic bottles, and any other objects that can collect water, as these are common breeding spots for mosquitoes.
In simple words: Cover water tanks. Spray insecticide. Use nets and repellent. Teach people about dengue. Remove old items that collect water.

Exam Tip: Include multiple levels of prevention - source elimination (removing breeding sites), personal protection (nets, repellent), and community action (campaigns, spraying) - for a well-rounded answer.

Question 8. Imagine you are in charge of a school health campaign. What key messages would you use to reduce communicable and non-communicable diseases?
Answer: For communicable diseases, my main messages would be: Wash your hands with soap regularly, especially before eating and after using the bathroom. Always cover your mouth and nose while coughing or sneezing. Drink only clean and safe water, not water from unknown sources. Keep classrooms and the school area clean and prevent water from collecting, which could allow mosquitoes to breed. Get vaccinated on time according to the health schedule. If you fall ill, stay home and rest rather than coming to school, so you do not pass the infection to others. For non-communicable diseases, my messages would be: Eat a balanced diet that includes fruits, vegetables, and whole grains, and reduce eating foods with high sugar and fat. Exercise daily, play outdoor games, or practice yoga to keep your body fit. Do not sit in front of screens for too long - limit your screen time and make sure you get enough sleep each night. Avoid harmful habits like smoking, drinking alcohol, or using drugs. Learn to manage stress through relaxation activities, hobbies, and talking with family or friends. A good slogan for this campaign could be: "Healthy Habits Today, Strong Future Tomorrow!"
In simple words: For spreading diseases: wash hands, cover coughs, drink clean water, get vaccinated, stay home when sick. For lifestyle diseases: eat healthy food, exercise, limit screen time, avoid smoking, and manage stress.

Exam Tip: Separate your messages into the two disease types clearly - examiners look for understanding that prevention strategies differ based on disease transmission method.

Question 9. It is recommended that we should not take an antibiotic for a viral infection like a cold, a cough or flu. Can you provide the possible reason for this recommendation?
Answer: Antibiotics are designed to work only against bacteria. They function by killing bacterial cells or stopping them from growing and multiplying. Colds, coughs, and flu are caused by viruses, not bacteria. Since antibiotics cannot kill viruses or stop their growth, they have no effect on these viral diseases. Additionally, using antibiotics incorrectly for viral infections can lead to a dangerous situation called antibiotic resistance. The bacteria living naturally in our body may develop resistance, meaning they stop responding to antibiotics. Later, if we truly need antibiotics for a serious bacterial infection, the medicine may not work properly because the bacteria have already become resistant. This is why medical professionals recommend taking antibiotics only when a doctor prescribes them for confirmed bacterial infections.
In simple words: Antibiotics kill bacteria, not viruses. Colds and flu are caused by viruses, so antibiotics cannot help. Using them wrongly makes germs resistant so they do not work later.

Exam Tip: Explain both reasons - antibiotics don't kill viruses AND overuse creates antibiotic resistance - this shows complete understanding of the issue.

Question 10. Which disease(s) among the following may spread if drinking water gets contaminated by the excreta from an infected person? Hepatitis A, Tuberculosis, Poliomyelitis, Cholera, Chickenpox.
Answer: Three diseases from this list spread through contaminated drinking water and food from infected persons' excreta. Hepatitis A spreads when water or food is contaminated with the virus from an infected person's waste. Poliomyelitis, or polio, spreads when water or food carries the poliovirus that was released in the faeces of an infected individual. Cholera is transmitted through water and food that have been contaminated with the bacterium that causes the disease. Tuberculosis spreads through air when an infected person coughs or sneezes, not through water. Chickenpox spreads through direct contact with the rash or through respiratory droplets in the air, not through contaminated water. Therefore, the diseases that would spread via contaminated drinking water are Hepatitis A, Poliomyelitis, and Cholera.
In simple words: Hepatitis A, polio, and cholera all spread through dirty water. Tuberculosis and chickenpox spread in other ways - not through water.

Exam Tip: List the diseases that DO spread by water and briefly explain why the others don't - showing you understand the transmission route for each disease.

Question 11. When our body encounters a pathogen for the first time, the immune response is generally low but on exposure to the same pathogen again, the immune response by the body is much more compared to the first exposure. Why is it so?
Answer: When our body meets a harmful germ or pathogen for the very first time, the immune system does not yet recognize it. Our immune cells need time to identify the invader and create specific antibodies that can fight it. Because of this unfamiliarity, the first immune response is weak and takes longer than we might like. However, after that first attack is fought off, something remarkable happens - our body creates memory cells. These special cells "remember" the pathogen and its characteristics. When the same pathogen tries to enter the body again, these memory cells immediately sound an alarm. The body then quickly produces large amounts of antibodies and destroys the invader much faster than it did the first time. This is also why vaccines work so well - they train the immune system and create memory cells in advance, before you actually encounter the real disease. This pre-prepared defense means your body can fight the disease quickly if exposure happens later.
In simple words: The first time a germ enters your body, it does not know what it is, so the fight is slow and weak. After beating it once, your body remembers it. Next time, your body fights back fast and strong. Vaccines teach your body this memory before you ever get sick.

Exam Tip: Include the concept of memory cells specifically - this is what examiners look for to distinguish a complete understanding of immunity from a surface-level answer. Also mention why vaccines are important in this context.