Selina Concise Solutions for ICSE Class 8 Biology Chapter 8 Diseases and First Aid

REVIEW QUESTIONS

Multiple Choice questions:

1. Put a tick mark (✓) against the correct alternative in the following statements:

(a) A mosquito is a vector for
1. Typhoid
2. Cholera
3. Malaria
4. Jaundice

Answer: 3. Malaria
Mosquitoes carry the Plasmodium parasite and pass it to humans through their bite. This makes them carriers of the disease rather than the direct cause.
Teacher's Tip: Remember "M" for Malaria and "M" for Mosquito.
Exam Tip: For full marks, always mention that a vector is a carrier of germs.

(b) Dengue is caused by a
1. Protozoan
2. Virus
3. Worm
4. Fungus

Answer: 2. Virus
Dengue fever is caused specifically by the dengue virus, which belongs to the Flaviviridae family. It is transmitted to people through the bites of infected Aedes species mosquitoes.
Teacher's Tip: Think of the "v" in Dengue (if you pronounce it slowly) to link it to "Virus".
Exam Tip: Be careful not to confuse vectors (mosquitoes) with causal agents (viruses).

(c) The idea of vaccination was conceived by
1. Charles Darwin
2. Alexander Flemming
3. Issac Newton
4. Edward Jenner

Answer: 4. Edward Jenner
Edward Jenner used cowpox material to create immunity to smallpox in humans in 1796. This was the first ever scientific attempt to control an infectious disease using a vaccine.
Teacher's Tip: Remember Jenner as the "Father of Immunology".
Exam Tip: Historical names are common in science exams, so match the scientist to their specific discovery.

(d) Which one of the following is not a psychotropic drug ?
1. Morphine
2. Cocaine
3. Heroin
4. Penicillin

Answer: 4. Penicillin
Psychotropic drugs are those that affect the mind, emotions, and behavior of a person. Penicillin is an antibiotic used to kill bacteria and does not affect the nervous system.
Teacher's Tip: Psychotropic means "acting on the mind," while antibiotics act on germs.
Exam Tip: Read the word "not" in the question very carefully before choosing your answer.

(e) Which one of the following is a communicable disease ?
1. Measles
2. Cancer
3. Heart stroke
4. Allergy

Answer: 1. Measles
Measles is highly contagious and spreads through the air when an infected person coughs or sneezes. Non-communicable diseases like cancer cannot be caught from another person.
Teacher's Tip: Communicable diseases can be "communicated" or passed from person to person.
Exam Tip: Always categorize diseases as infectious or non-infectious during your revision.

(f) Cataract is a disease of: -
1. Ears
2. Nose
3. Eyes
4. Throat

Answer: 3. Eyes
A cataract is a clouding of the normally clear lens of the eye, making it hard to see. It usually develops slowly and can eventually lead to blindness if not treated.
Teacher's Tip: Think of a "cloudy" window when remembering cataracts in the eye.
Exam Tip: Mention that it affects the "lens" of the eye for a more detailed answer.

(g) Infectious diseases can be prevented by:
1. Medicines
2. Proper food
3. Immunisation
4. Exercise

Answer: 3. Immunisation
Immunisation helps the body's immune system recognize and fight off specific germs before they can cause illness. This is the most effective proactive way to stop the spread of infections.
Teacher's Tip: Immunisation makes your body a "fortress" against germs.
Exam Tip: Remember that "prevention" is different from "treatment" (like medicines).

(h) Which one of the following is a genetic disease ?
1. Scurvy
2. Leukemia
3. Goitre
4. Haemophilia

Answer: 4. Haemophilia
Genetic diseases are passed down from parents to children through DNA and are present from birth. Haemophilia is a condition where the blood does not clot properly due to inherited traits.
Teacher's Tip: Genetic diseases are like family traits that you are born with.
Exam Tip: Differentiate genetic diseases from deficiency diseases like scurvy or goitre.

(i) Which one of the following is a degenerative disease ?
1. Thalassemia
2. Beri-beri
3. Cataract
4. Diabetes

Answer: 3. Cataract
Degenerative diseases occur when organs or tissues gradually wear out or stop working correctly as we age. Cataracts are a prime example because the eye lens often clouds up over many years.
Teacher's Tip: Degenerative means "to break down over time."
Exam Tip: Age-related issues are usually classified as degenerative diseases.

(j) Pellagra is one disease caused by the deficiency of:
1. Vit. B₃
2. Vit. B₁
3. Vit. C
4. Vit. D

Answer: 1. Vit. B₃
Pellagra is a condition that occurs when a person does not have enough niacin (Vitamin B₃) in their diet. It is often characterized by the "four Ds": dermatitis, diarrhea, dementia, and death.
Teacher's Tip: Link the "P" in Pellagra to the niacin group in your mind.
Exam Tip: Memorize the vitamin table carefully, as deficiency questions are very frequent.

(k) Hay fever and asthma are
1. Deficiency diseases
2. Genetic diseases
3. Organic diseases
4. Allergy diseases

Answer: 4. Allergy diseases
Allergies are overreactions of the immune system to substances like pollen or dust that are usually harmless. These conditions can cause breathing difficulties or sneezing in sensitive individuals.
Teacher's Tip: Think of allergies as the body's "over-sensitive" alarm system.
Exam Tip: Group Hay fever and Asthma together under the "Allergy" category.

(l) Which one of the following vitamin deficiency diseases can be cured by eating a diet which includes carrot, yellow fruits, vegetables, butter, milk, fish ?
1. Beri-beri
2. Dermatitis
3. Night blindness
4. Scurvy

Answer: 3. Night blindness
Night blindness is caused by a lack of Vitamin A, which is found in high amounts in colorful vegetables like carrots. Eating these foods helps the eyes maintain proper vision in dim light.
Teacher's Tip: Carrots help you see in the dark—just like a superhero!
Exam Tip: Link the source (Carrot) directly to the vitamin (Vit. A) and its disease (Night Blindness).

Short Answer Questions:

Question 1(a): What is a non-communicable disease ?
Answer: The diseases which are caused due to improper functioning of the body organs e.g. diabetes, heart attack. They are not caused by germs and not transmitted from one to another.
These diseases stay within the person and cannot be "caught" by standing next to them. They usually develop over a long time due to lifestyle choices or genetics.
Teacher's Tip: Think of "Non-communicable" as "Non-catching."
Exam Tip: Mentioning "organ malfunctioning" is a key technical phrase for full marks.

Question 1(b): What are communicable diseases ?
Answer: Those disease which spread from one person to another by the entry of microorganisms are known as communicable diseases.
These are infectious illnesses caused by pathogens like bacteria, viruses, and fungi. They can be passed through air, water, food, or direct physical contact.
Teacher's Tip: Communicable = Catchable.
Exam Tip: Always include "microorganisms" or "germs" in your definition of communicable diseases.

Question 1(c): How can we control spreading of diseases by mosquitoes and houseflies ?
Answer: We can control spreading of diseases by mosquitoes and houseflies by using repellants, throwing garbage in covered bins, avoiding stagnation of water and checking breeding of these insects.
Mosquitoes need standing water to lay eggs, so removing old containers helps stop their lifecycle. Houseflies thrive on trash, so keeping our surroundings clean prevents them from carrying germs to our food.
Teacher's Tip: "Clean home, clean health"—garbage and stagnant water are insect hotels.
Exam Tip: Give at least two specific methods to get full marks on control measures.

Question 1(d): Public hygiene is equally important as personal hygiene. Give reasons.
Answer: Keeping oneself clean is personal hygiene. But public hygiene is equally important as dirty surrounding may lead to more of houseflies, mosquitoes and other insects which are major vectors of many communicable diseases. Clean surrounding also provides good mental health as it soothes our mind.
Personal cleanliness won't protect you if the environment around you is filled with disease-carrying insects. Public hygiene ensures that the entire community stays safe by preventing mass breeding of pathogens.
Teacher's Tip: You can't be truly healthy in a dirty neighborhood.
Exam Tip: Use the word "vectors" when explaining why dirty surroundings are dangerous.

Question 1(e): What is a deficiency disease ?
Answer: These disease are caused by lack of nutrients, vitamins, minerals as a anaemia, goitre.
When our diet lacks essential building blocks for long periods, the body cannot function properly. For example, without enough iron, the body cannot make enough red blood cells, leading to anaemia.
Teacher's Tip: Deficiency = "Something is missing."
Exam Tip: Provide at least one example of a nutrient and its related disease.

Question 1(f): Biting nails should be strictly avoided. Give reason.
Answer: Nail biting may cause many disease as the dirt has many bacteria causing diseases. Nails should be cut from time to time to save from diseases.
Bacteria and worm eggs often hide under the tips of fingernails where they are hard to wash away. When you bite your nails, you are swallowing these germs directly into your digestive system.
Teacher's Tip: Nails are like "germ traps" for your fingers.
Exam Tip: Mention "bacteria" and "ingestion" to explain the danger clearly.

Question 1(g): Regular exercise and proper rest is a must. Give reason.
Answer: Regular exercise keeps our body strong and immune to many diseases, rest refreshes our body.
Exercise improves blood circulation and helps the immune system work better at fighting germs. Rest is when the body repairs its tissues and recharges its energy for the next day.
Teacher's Tip: Exercise is the "battery charger" for your muscles, and sleep is the "reset" button for your brain.
Exam Tip: Use the words "immunity" and "repair" in your explanation.

Question 1(h): Children eating more of fast food tend to suffer from obesity (overweight). Comment.
Answer: Fast food like pizza, burger, patty, oily foods etc. have much carbohydrates and fats. Children eating these become more and more fat and gain weight soon as they do not do much of physical work.
These foods contain "empty calories" which provide energy but very little of the vitamins the body needs to stay healthy. When this extra energy is not used up through playing or sports, it is stored in the body as fat.
Teacher's Tip: Fast food is "slow health"—it's okay sometimes, but not every day!
Exam Tip: Explain the link between high "fats/carbs" and "lack of physical activity."

2. Name the following:

Question 2(a): A viral disease caused due to unhealthy sexual contact
Answer: AIDS.
AIDS is caused by the Human Immunodeficiency Virus (HIV). It severely weakens the immune system, making it difficult for the body to fight off other infections.
Teacher's Tip: AIDS stands for Acquired Immune Deficiency Syndrome.
Exam Tip: Be accurate with acronyms; writing the full name can show you studied well.

Question 2(b): A disease caused due to Plasmodium
Answer: Malaria.
Plasmodium is a protozoan parasite that invades red blood cells. It is carried from person to person by the female Anopheles mosquito.
Teacher's Tip: Link Plasmodium and Malaria as a pair.
Exam Tip: If asked for the type of microorganism, state that Plasmodium is a protozoan.

Question 2(c): A disease caused by the bite of female Anopheles mosquito
Answer: Malaria.
Only the female mosquito bites because she needs the protein from blood to develop her eggs. When she bites, she injects the Plasmodium parasite into the victim's bloodstream.
Teacher's Tip: It's always the female mosquito that causes the trouble!
Exam Tip: Be sure to include the specific name "Anopheles" in your answers.

Question 2(d): Two viral diseases caused by mosquito bites
Answer: Dengu, Chikungunya.
Dengue and Chikungunya are both transmitted by the Aedes aegypti mosquito. They cause high fever and severe joint pain in infected patients.
Teacher's Tip: Note that "Dengue" is spelled "Dengu" in your textbook text.
Exam Tip: Listing two distinct diseases is necessary for full credit here.

Question 2(e): Any droplet - borne disease.
Answer: Amoebiasis, Cholera, Hepatitis A.
Droplet-borne diseases are those spread through tiny moisture particles released when an infected person coughs or sneezes. While the textbook list includes water-borne examples here, standard droplet-borne ones are the common cold or flu.
Teacher's Tip: Use a tissue when you sneeze to catch those droplets!
Exam Tip: Standard droplet diseases often affect the respiratory system.

Question 2(f): A viral disease caused by the bite of a dog
Answer: Rabies/Hydrophobia
Rabies is a fatal viral infection that attacks the central nervous system. "Hydrophobia" means fear of water, which is a classic symptom in the later stages of the disease.
Teacher's Tip: Always get a vaccine shot immediately if bitten by a stray animal.
Exam Tip: Use "Rabies" as the primary name and "Hydrophobia" as the symptom name.

Question 2(g): A disease due to choking of coronary artery
Answer: Atheraosclerosis.
Atherosclerosis occurs when plaque (fatty deposits) builds up inside the arteries. This narrowing makes it harder for blood to reach the heart muscle, potentially leading to heart attacks.
Teacher's Tip: Think of it like a clogged pipe in your house.
Exam Tip: Connect "coronary artery" to "heart" function in your explanations.

Question 2(h): Two diseases caused due to deficiency of protein in the diet of a child.
Answer: Kwashiorkor and marasmus.
Kwashiorkor usually affects children who get enough calories but not enough protein, leading to a swollen belly. Marasmus is total starvation, where the child lacks both protein and energy.
Teacher's Tip: Proteins are "Body Building" blocks—kids need them to grow!
Exam Tip: Be able to identify these two specific names as PEM (Protein Energy Malnutrition) diseases.

3. Write short (2-3 sentences) notes on the following:
Disease, immunisation, pathogen, AIDS, vaccination, vector.

Answer:
Disease: Disease is a departure from normal health due to structural or functional disorder of the body. Disease may be due to deficiency of nutrients or malfunctioning of organs or 1 genetic disorders, improper metabolic activity, or allergies, or cancer and mental illness as diabetes, haemophilia, leukemia, schizophrenia.
A disease makes you feel "un-easy" because your body isn't working the way it should. It can be caused by something external like germs or something internal like organ failure.
Teacher's Tip: Disease = "Dis-ease" (Not at ease).
Exam Tip: Classify the type of disease (infectious vs. non-infectious) in your note.

Immunisation: It means, we make the body immune to certain diseases by introducing respective weakened germs into the body. Thus we develop resistance to the concerned disease this process is called immunisation. The germs or the material introduced into the body to make it resistant to the concerned disease is called vaccine. This produces antibodies in the body of the person and the person can be saved by these antibodies. The vaccine can be given by the injection or orally as polio drops, tap vaccine for typhoid, BCG vaccine for tuberculosis.
Immunisation is the act of training your immune system to recognize a specific "enemy." Once trained, your body keeps these "memories" as antibodies to protect you in the future.
Teacher's Tip: Immunisation is like giving your body a "wanted poster" for a specific germ.
Exam Tip: Mention "antibodies" to show you understand how the body defends itself.

Pathogens: The germs that cause diseases to human beings and to other animals and plants are called pathogens. They spread the diseases from person to person or through the air or through the articles of the diseased persons. Pathogens may be different kinds of bacteria, viruses, fungi, protozoans or worms.
Pathogens are invisible biological invaders that disrupt the normal working of our cells. Every infection you have ever had was started by one of these microorganisms.
Teacher's Tip: Think of pathogens as "bad germs."
Exam Tip: List the four main types (Bacteria, Virus, Fungi, Protozoa) for a complete note.

AID’S (Acquired Immune Deficiency Syndrome): It is a viral disease caused by the virus called HIV (Human immuno deficiency virus) This virus makes the defence mechanism of the human body very weak. The immune system in the body as W.B.C. becomes weak. Thus the person catches the infectious diseases very easily. This disease spreads through sexual contact as one of the partner may be carrier of the disease. It may spread through the blood transfusion and infected syringes, blades of the barbers, it may infect the developing baby through the blood by the mother. It is very deadly disease.
AIDS is dangerous because it takes away the body's natural ability to heal itself. Because the immune system is destroyed, even a simple cold can become life-threatening for the patient.
Teacher's Tip: "Acquired" means you are not born with it; you get it from outside.
Exam Tip: Always mention HIV as the causal virus when writing about AIDS.

Vaccination: Vaccination is a method of making the body immune to a particular disease by injecting killed or weakened disease causing microbe into a body to stimulate the formation of antibodies and develop immunity to that disease causing microbe.
The substance used is called a vaccine, which contains a safe version of the germ. This triggers the body's natural defense without making the person actually sick with the full disease.
Teacher's Tip: A vaccine is like a "practice match" for your immune system.
Exam Tip: Use terms like "weakened microbe" and "antibodies" for high marks.

Vector: A vector is an organism that carries disease causing microbes (pathogens) from one host to another. They are the carriers of infection. Example: Mosquito, housefly, etc.
Vectors are like biological "delivery trucks" that transport germs to healthy people. While the vector doesn't usually get sick from the germ, the person they bite or land on certainly does.
Teacher's Tip: Vector = Vehicle for germs.
Exam Tip: Give at least two examples like "mosquito" and "housefly" in your definition.

P.Q. Fill in the blanks by selecting suitable words given below:
(clotting, goitre, insuline, rickets, iron, proteins)

(a) Anaemia is caused due to the deficiency of iron.
(b) Deficiency of Vit. D causes rickets in children.
(c) Deficiency of iodine in the diet may cause goitre.
(d) Diabetes is caused due to undersecretion of insulin.
(e) Kwashiorkor is caused due to the deficiency of proteins.
(f) Haemophilia is a disease caused due to slow clotting of the blood.
Answer: Fill in the blanks using the provided words as shown above.
Each blank identifies a specific link between a nutrient or hormone and a disease. For example, iron is needed for blood, and iodine is needed for the thyroid gland.
Teacher's Tip: Practice these links: Iron-Anaemia, Iodine-Goitre, Vit D-Rickets.
Exam Tip: Double check spelling, especially for "insulin" and "rickets."

P.Q. Find the odd one out:

(a) Typhoid, cholera, jaundice, tuberculosis, tetanus.
Answer: Jaundice is odd one
While the other four are specific bacterial infections, jaundice is a symptom of many different liver problems. It indicates that the liver is not processing waste correctly.
Teacher's Tip: Jaundice is a "sign" (yellow skin), while the others are "names" of diseases.
Exam Tip: Always give a reason for why you picked the "odd one out."

(b) Cold, AIDS, plague, malaria, measles.
Answer: Malaria is odd one.
Malaria is caused by a protozoan parasite, whereas the other diseases in the list are caused by viruses or bacteria. It also requires a specific mosquito vector to spread.
Teacher's Tip: Protozoa are much larger than viruses!
Exam Tip: Grouping by causal agent (virus vs parasite) is a smart way to find the odd one.

(c) Scurvy, rickets, haemophilia, pellagra, night blindness.
Answer: Haemophilia is odd one.
Haemophilia is a genetic disease you are born with, while all the others are caused by missing vitamins in your food. You cannot cure haemophilia just by changing your diet.
Teacher's Tip: Genetic = Inherited; Others = Deficiency.
Exam Tip: Look for the "source" of the disease to find the odd one.

(d) Proteins, carbohydrates, fats, minerals, cancer.
Answer: Cancer is odd one.
Cancer is a disease, while proteins, carbohydrates, fats, and minerals are all types of nutrients found in food. One is an illness, and the others are parts of a healthy diet.
Teacher's Tip: One is a "problem," and the others are "fuel" for the body.
Exam Tip: Identify the category (nutrient vs disease) to solve this.

P.Q. Fill in the blank in the following table:

Vitamin: (a) Vitamin A
Name of the deficiency diseases: Night blindness
Source of vitamin: Carrot, fish milk, yellow fruits.
Function of vitamin: Growth of hair, skin

Vitamin: (b) Vitamin B₁
Name of the deficiency diseases: Beri-beri
Source of vitamin: Eggs, nuts, legume
Function of vitamin: Carbohydrate metabolism.

Vitamin: (c) Ascorbic acid (Vitamin C)
Name of the deficiency diseases: Scurvy (bleeding gums)
Source of vitamin: Citrus fruits, tomatoes
Function of vitamin: Develops immunity

Vitamin: (d) Vitamin D
Name of the deficiency diseases: Rickets (in childhood) bones turn soft
Source of vitamin: Sun light, milk, butter fish liver oil, egg yolk
Function of vitamin: Controls calcium phosphorus, metabolism.
Answer: Completed table data provided above.
Vitamins are essential micronutrients that act like catalysts for body functions. For example, Vitamin D is crucial because without it, your body cannot use the calcium from your food to build strong bones.
Teacher's Tip: Vitamin C is found in "sour" (citrus) fruits like lemons and oranges.
Exam Tip: Practice drawing this table from memory, as it covers multiple possible questions.

Long Answer Questions:

Question 1: What is vaccination? Mention the four ways in which vaccine’s are prepared, giving the name of one disease for which each type of vaccine is used.
Answer: For developing resistance in the body we introduce germs or germ substances in the body to develop resistance in the body against a particular disease. The material introduced into the body is called vaccine, this practice is called prophylaxis. The germ or the germ substance is put into the body orally as polio drops or it is introduced by injection as TAB vaccine. Vaccine or vaccination was attached with small pox, but it is now used in a general sense.
Preparation:
1. Killed germs are introduced into the body These act as vaccine for TAB, vaccine for typhoid, Salk’s vaccine for poliomyelitis. Rabies vaccine for dog bite.
2. Living weakened germs: The living germs are treated in such a way that they become very weak and as such, they cannot cause the disease. They can induce antibody formation such as the vaccine for measles and the freezed dried BCG vaccine for tuberculosis.
3. Living fully virulent germs: These virulent germs in small doses are introduced into the body as vaccine and these produce antibodies in the body and these do not allow the germs of particular type to cause that disease: In this vaccination the person is inoculated with cowpox virus. It is very similar to small pox virus.
4. Toxoids: Toxoids are prepared from the extracts., of toxins secreted by bacteria. These toxins are poisons and these are made harmless by adding formalin into them. They retain their capacity and as a result when introduced into the body they produce antibodies into the body and do not allow the germs to grow in the body as vaccines for diphtheria and tetanus.
Vaccination uses the body's natural "learning" ability to fight off deadly threats. By showing the immune system a safe version of the germ, we prepare it to win the battle if the real germ ever enters our body.
Teacher's Tip: Prophylaxis is just a fancy word for "preventing disease."
Exam Tip: Memorize one disease for each preparation type (e.g., TAB for Typhoid, BCG for TB).

Question 2: Burns can be superficial burns, deep burns or chemical burns. What emergency care you would suggest in each case.
Answer: When one gets burnt up accidentaly one should not pull clothes from the burnt area and one should not cut the blisters. One should apply butter, vaseline or ointment.
• Superficial burns: When there are superficial bums, put cold water on it and apply some oily substance, bumol, castor oil, vaseline, butter etc.
• Deep burns: When there are deep bums do not put cold water on the burnt area. Seek the help of hospital and one should be kept under the treatment of some expert doctor of skin.
• Chemical burns: In case of chemical burns i.e., due to acid and other chemicals, wash with running water for 10 minutes and then cover with dressing.
First aid for burns depends on how many layers of skin are damaged. Cold water is great for minor heat burns, but chemical burns need much more washing to get the harmful substances completely off the skin.
Teacher's Tip: Never pop a blister—it's nature's own sterile bandage!
Exam Tip: Be specific about washing chemical burns with "running water" for at least 10 minutes.

Question 3: Describe the ways in which communicable diseases are transmitted through various indirect methods.
Answer: Indirect methods of transmission of communicable diseases:
1. Using items used by the infected persons: The healthy persons may be infected by using the articles like towel, hankey, utensils, bedding used by the patient infected by the communicable diseases. Diseases like tuberculosis, ring worm; common cold, influenza are transmitted by this method.
2. Contaminated food and water: Diseases like dysentery, cholera spread through the contaminated food and water. Flies sitting on the food, if taken by a healthy person may be infected by the germs which may cause vomiting and loose motions. Similarly water and food infected by entamoeba may cause dysentery to persons who may take contaminated food.
3. Vectors or carriers: Organisms like mosquitoes and house flies, ticks carry germs from the source of infection and pass on the germs to the normal persons and thus they are infected by diseases like malaria, cholera, plague. These organisms which carry the disease are called vectors and are not infected themselves. Mosquitoes suck blood and carry the disease causing protozoans from infected persons to healthy persons. Similarly houseflies carry the germs from garbage and sewage to the food. If this food is taken by the persons they become prey to typhoid and other diseases.
4. Air: One sneeze from a person infected by cold may give billions of germs which are carried by air and may infect the healthy person. Tuberculosis passes from one person to other by coughing or sneezing of the infected person. These germs remain suspended in the air and persons may be infected by these spores or germs. Common cold, measles, diptheria, chicken pox.
Indirect transmission means you don't have to touch the sick person to get sick. Germs can travel through shared objects, insects, or even the air we all breathe in a room.
Teacher's Tip: Germs are "hitchhikers" that use air, water, and flies to travel.
Exam Tip: Name the four main indirect routes (Items, Food/Water, Vectors, Air) for a complete answer.

Question 4: Given a crossword puzzle. Read the clues across and clues downward, and fill up the blank squares. Check up your performance with the correct solution given at the end.
Clues across
1. Category of pathogen that causes diseases, like common cold and mumps.
2. These may readily grow in your hair, if you do not wash it regularly.
3. This is the vaccine for preventing tuberculosis.
4. Cover this part of your body by a handkerchief while sneezing to prevent droplet infection to others.
5. The disease pertussis is popularly known as whooping
6. One of the most common insects which visits our exposed foods and contaminates them.
7. A disease that weakens body’s defence system against infections.
Clues down
8. Germ or germ - substance introduced into the body to prevent occurrence of an infectious disease.
9. A disease in which the eyes, the skin and the urine turn yellow.
10. An organ usually affected by tuberculosis.
11. A disease caused by the bite of an infected dog, and which affects the central nervous system.

Answer:
Clues Across:
1. VIRUS
2. LICE
3. BCG
4. NOSE
5. COUGH
6. FLIES
7. AIDS
Clues Down:
8. VACCINE
9. JAUNDICE
10. LUNGS
11. RABIES
Crosswords help us remember scientific terms by linking them to their definitions. For instance, knowing that Rabies affects the "central nervous system" is a key part of the clue for 11 Down.
Teacher's Tip: BCG is a unique three-letter name for a very important vaccine.
Exam Tip: Practice identifying a disease from just one major symptom, like "yellow skin" for Jaundice.

ADDITIONAL QUESTIONS

I. Multiple choice questions. Tick (✓) the correct choice:

1. Which of the following is a disease caused by bacteria?
1. cholera
2. AIDS
3. malaria
4. rabies

Answer: 1. cholera
Cholera is caused by the bacterium Vibrio cholerae. It usually spreads through contaminated water and causes severe diarrhea and dehydration.
Teacher's Tip: "B" for Bacteria, "C" for Cholera—they are alphabetical neighbors!
Exam Tip: Remember that AIDS and Rabies are viral, while Malaria is caused by protozoa.

2. Which of the following is not a viral disease?
1. pneumonia
2. measles
3. polio
4. rabies

Answer: 1. pneumonia
Most common types of pneumonia are caused by bacteria, although it can occasionally be caused by viruses. Measles, Polio, and Rabies are strictly viral infections.
Teacher's Tip: Pneumonia affects the tiny air sacs in your lungs.
Exam Tip: Look out for words like "not" which change the whole meaning of the question.

3. Ringworm is a disease caused by
1. protozoa
2. bacteria
3. virus
4. fungi

Answer: 4. fungi
Despite its name, ringworm is not caused by a worm; it's a fungal skin infection. It creates itchy, red, circular patches on the skin that look like rings.
Teacher's Tip: Don't let the name "worm" trick you—it's definitely a fungus!
Exam Tip: Common skin infections like athlete's foot and ringworm are caused by fungi.

4. Kwashiorkor is caused by
1. smoking
2. worms
3. virus
4. imbalance in diet

Answer: 4. imbalance in diet
Specifically, it is caused by a severe lack of protein in the diet. This imbalance leads to malnutrition, which affects the physical and mental growth of children.
Teacher's Tip: Diet is the "instruction manual" for your body—if a page is missing, things go wrong.
Exam Tip: "Imbalance in diet" is a broad term for malnutrition.

II. Fill in the blanks :
1. Over-eating causes a disease called obesity.
2. Food poisoning is caused by bacteria.
3. One of the diseases caused by protozoa is malaria.

Answer: Fill in the blanks with the bold words as shown above.
Obesity is a major modern health issue caused by consuming more energy than we use. Food poisoning often happens when bacteria like Salmonella grow on food that hasn't been stored properly.
Teacher's Tip: Eat just enough, not too much!
Exam Tip: Link the causal organism (e.g., protozoa) to the disease (malaria) correctly.

III. Find the odd one out, giving reason:
Pneumonia, cholera, leprosy, measles Measles:

Answer: Measles: is the odd-one out as it a disease caused by a virus while the rest three are bacterial diseases. -
Bacteria can often be treated with antibiotics, but viral diseases like measles must be managed through vaccination. Measles is also highly distinctive because of the red rashes it causes on the body.
Teacher's Tip: Think of measles as the "Viral Visitor."
Exam Tip: Be sure to name the category of the other three items in your reason.

IV. Define the following:

1. Diseases:
Answer: Any disorder or abnormal working of an organ, part or system of the body leads to illness called as disease.
Diseases disrupt the harmony of the body and can make you feel weak or pained. They are the body's way of telling us that something is structurally or functionally wrong.
Teacher's Tip: A disease is any "glitch" in the body's machinery.
Exam Tip: Use terms like "abnormal working" to make your definition sound scientific.

2. Malnutrition:
Answer: The condition of nutrition in which the food is either in inadequate quantity or in excess or it lacks in some essential nutrient is called malnutrition.
Malnutrition doesn't just mean being hungry; it can also mean eating too much of the wrong things. Your body needs a perfect balance of vitamins and minerals to thrive.
Teacher's Tip: Malnutrition = Bad nutrition.
Exam Tip: Remember to include "excess" as a form of malnutrition, not just "lack."

V. Name the following:

Question 1: Two diseases each caused by bacteria, protozoa and virus.
Answer: Two diseases caused by bacteria are pneumonia and cholera. Two diseases caused by protozoa are malaria and amoebiasis. Two diseases caused by virus are chicken pox and AIDS.
Grouping diseases by their causes is a great way to understand how they spread and how they are treated. For example, bacterial diseases usually respond well to antibiotics, but viral ones do not.
Teacher's Tip: Keep a mental list of "Pairs" for each type of germ.
Exam Tip: Double-check you haven't swapped a viral disease for a bacterial one.

Question 2: Organism which causes malaria.
Answer: Protozoa (called Plasmodium).
Plasmodium is a tiny single-celled organism that travels through the bloodstream. It reproduces inside your red blood cells, causing them to burst and release toxins.
Teacher's Tip: Plasmodium is the "thief" that hides in your blood cells.
Exam Tip: Give both the category (Protozoa) and the name (Plasmodium) for full marks.

Question 3: Cause of obesity.
Answer: Excess of food (ovemutrition).
When we eat more calories than our body burns, the extra energy is stored as body fat. This often happens when people eat a lot of junk food and spend long hours sitting down.
Teacher's Tip: Move more, eat just right!
Exam Tip: Mention "overnutrition" as the technical term for the cause.

VI. Answer the following questions:

Match columns data:
Column A
1. Beri-beri
2. Anaemia
3. Scurvy
4. Rickets
5. Goitre
6. Night blindness

Column B
(a) Vitamin C
(b) Vitamin D
(c) Vitamin A
(d) Vitamin B₁
(e) Iron
(f) Iodine
Answer:
1. Beri-beri -> (d) Vitamin B₁
2. Anaemia -> (e) Iron
3. Scurvy -> (a) Vitamin C
4. Rickets -> (b) Vitamin D
5. Goitre -> (f) Iodine
6. Night blindness -> (c) Vitamin A
Follow the matching as listed above.
This exercise connects specific nutrients to their health roles. For instance, Vitamin D is the "partner" to calcium for building strong bones.
Teacher's Tip: "C" for Citrus, "C" for Vitamin C, "C" for Scurvy (well, close enough!).
Exam Tip: Draw straight lines for matches and always double-check your work.

Question 1:
List the causes of diseases.
Answer: Diseases develop due to a number of causes such as:
1. imbalances in the diet.
2. infection by micro-organisms.
3. malfunctioning of body organs.
4. allergic reactions to substances in the environment.
5. social factors such as smoking, alcoholism, drug addiction, unhealthy life style.
Knowing the cause of a disease helps doctors choose the right treatment. For example, a dietary imbalance is fixed with better food, but an infection requires germ-fighting medicine.
Teacher's Tip: Health is a balance of what you eat, where you live, and how you act.
Exam Tip: List at least three distinct points when asked to "list causes."

Question 2: What are deficiency diseases?
Answer: The diseases caused by inadequate intake of food or the lack of some essential nutrient in our diet are called deficiency diseases.
Our bodies are like complex machines that need many different "fuels" to run correctly. If even one small part, like a specific vitamin, is missing, the whole machine starts to fail.
Teacher's Tip: A "deficient" diet is an incomplete diet.
Exam Tip: Use the word "nutrient" in your definition for precision.

Question 3: Differentiate between undernutrition and malnutrition.
Answer:
Undemutrition:
1. It is a condition of nutrition where food is inadequate.
2. It leads to deficiency diseases.
3. Undemutrition is a form of malnutrition
Malnutrition:
1. It is condition of nutrition where food is either inadequate, or excess or lacks some essential nutrient.
2. It leads to deficiency diseases and obesity.
3. Malnutrition has many forms like undemutrition, overnutrition or imbalance of nutrients in diet.
Undernutrition is about not having enough to eat, while malnutrition is a broader term that includes eating badly or too much. Both conditions prevent the body from being healthy and strong.
Teacher's Tip: Malnutrition is the "Big Umbrella" that includes undernutrition and overnutrition.
Exam Tip: Use a table or clear bullet points to show differences between the two.

DEFICIENCY DISEASES

I. Multiple choice questions. Tick (✓) the correct choice:

1. Kwashiorkor is a disease caused by
1. microbes
2. deficiency of nutrients
3. environment
4. defects in body organs

Answer: 2. deficiency of nutrients
Specifically, it is a lack of high-quality protein. This deficiency causes fluid to leak into the body tissues, which is why children with this disease have swollen bellies.
Teacher's Tip: Nutrients are the tools your body uses to build itself.
Exam Tip: Be sure to specify "protein" if the question gets more detailed.

2. Deficiency of vitamin C causes
1. scurvy
2. beri-beri
3. rickets
4. skin diseases

Answer: 1. scurvy
Scurvy is famous as the "sailor's disease" because long-ago sailors didn't have fresh fruit. It causes the gums to bleed and wounds to take a very long time to heal.
Teacher's Tip: Vitamin C keeps your "skin and gums" strong and healthy.
Exam Tip: Remember "C" for citrus and "Scurvy."

3. Deficiency of vitamin K can cause
1. haermorrhage
2. bleeding gums
3. rickets
4. skin diseases

Answer: 1. haermorrhage
Vitamin K is essential for blood clotting. Without it, even a small cut would keep bleeding, which can lead to serious internal blood loss called hemorrhage.
Teacher's Tip: Vitamin K is the "K-lotting" vitamin (clotting starts with C, but sounds like K!).
Exam Tip: "Hemorrhage" is the scientific term for uncontrolled bleeding.

II. Fill in the blanks:
1. Protruding belly is a symptom noticed in kwashiorkor.
2. The disease kwashiorkor results from the deficiency of proteins.
3. The mineral fluorine is responsible for tooth decay.

Answer: Fill in the blanks with the bold words as shown above.
A protruding belly happens because low protein levels cause the body to retain too much water. Fluorine is often added to water or toothpaste because it makes your tooth enamel harder and more resistant to acid.
Teacher's Tip: "P" for Protein, "P" for Protruding belly.
Exam Tip: Spelling is key for "kwashiorkor"—practice it five times!

III. Find the odd one out, giving reasons:

1. Kwashiorkor, scurvy, beri-beri, night blindness.
Answer: Kwashiorkor: Kwashiorkor is the odd-one out as it is a protein deficiency. disease while the rest three are vitamin deficiency diseases.
Kwashiorkor results from lack of protein, which is a macronutrient the body needs in large amounts. The other three result from missing micronutrients (vitamins) that the body needs in tiny amounts.
Teacher's Tip: Macronutrient vs. Micronutrient is the real difference here.
Exam Tip: Always state what the "others" have in common in your answer.

2. Goitre, tooth decay, anaemia, rickets.
Answer: Rickets: Rickets is the odd-one out as it is a vitamin deficiency disease while the rest three are mineral deficiency diseases.
Goitre comes from missing iodine, tooth decay from missing fluorine, and anaemia from missing iron. Rickets is the only one here caused primarily by missing a vitamin (Vitamin D).
Teacher's Tip: Minerals come from the earth, vitamins come from living things (plants/animals).
Exam Tip: Be very clear about the difference between a "vitamin" and a "mineral."

IV. Name the following:

Question 1: Three vitamin-deficiency diseases.
Answer:
1. Night blindless (due to deficiency of Vitamin A).
2. Scurvy (due to deficiency of Vitamin C).
3. Rickets (due to deficiency of Vitamin D).
These diseases show how vital vitamins are for specific systems like our eyes, skin, and bones. Even though we only need a tiny amount, we must get them from our food every day.
Teacher's Tip: Think of vitamins as the "essential tools" for your body parts.
Exam Tip: Always name the specific vitamin responsible for the disease in your answer.

Question 2: Three mineral-deficiency diseases.
Answer:
1. Anaemia (due to deficiency of iron).
2. Goitre (due to deficiency of iodine).
3. Tooth decay (due to deficiency of fluorine).
Minerals are inorganic elements that the body uses for building structures or signaling. For instance, iron is a critical part of the hemoglobin that carries oxygen in your blood.
Teacher's Tip: Minerals are the "hardware" of your body.
Exam Tip: Connect Iron-Anaemia and Iodine-Goitre as your go-to examples.

V. Mention the food constituents which may be lacking in one’s diet, in case of the following:

1. A child having rickets.
2. A person suffering from scurvy.
3. A person suffering from beri-beri.
4. A child suffering from kwashiorkor.
5. A person suffering from poor eyesight.
6. A person suffering from anaemia.
Answer:
1. Vitamin D and calcium.
2. Vitamin C.
3. Vitamin B.
4. Protein and energy giving carbohydrates.
5. Vitamin A.
6. Iron.
Identifying the missing part of the diet is the first step toward curing a deficiency disease. Adding the right foods, like citrus for scurvy or leafy greens for anaemia, restores the body's health.
Teacher's Tip: "You are what you eat"—if you're sick, check your plate first!
Exam Tip: For rickets, don't forget to mention both Vitamin D and Calcium.

VII. Answer the following questions:

Question 1: What is meant by PEM? Name the diseases caused by PEM.
Answer: PEM (Protein energy malnutrition) is a term used to describe diets which lack proteins and energy giving carbohydrates. They are common among children. Kwashiorkor and marasmus are diseases which result from PEM.
PEM is one of the most serious health problems for children in developing areas. Without enough fuel and building materials, a child's body cannot develop its brain or muscles properly.
Teacher's Tip: PEM = "Protein + Energy" Malnutrition.
Exam Tip: Define the acronym first, then list the two specific diseases.

Question 2: Give the symptoms of kwashiorkor and marasmus.
Answer:
Symptoms of kwashiorkor:
1. Protruding belly.
2. Dark and scaly skin.
3. Brownish hair.
4. Stunted growth; underweight.
5. Swollen legs due to water accumulation.
6. Anaemia.
7. Mental retardation.
8. Reduced immunity.
9. Loss of appetite.
10. Loss of appetite
Symptoms of Marasmus:
1. Poor muscle development.
2. Bones showing through skin, no fat.
3. Weak legs.
4. Anaemia.
5. Grossly underweight.
6. Mental retardation.
7. Reduced immunity.
8. Loss of appetite.
While both are caused by lack of food, they look very different. A child with kwashiorkor looks "puffy" due to swelling, while a child with marasmus looks "wasted" because they have used up all their fat and muscle.
Teacher's Tip: Kwashiorkor = Swelling; Marasmus = Skin and Bone.
Exam Tip: Compare the "physical appearance" symptoms to show you know the difference.

Question 3: Why should we not eat polished rice?
Answer: Polished rice is an example of ‘processed’ food. Processing removes many of the Vitamin B’s. Beri-beri is caused by the lack of Vitamin Br Therefore, we should not eat polished rice.
The outer layer of the rice grain, called the bran, contains most of its nutrients. When we polish rice to make it white and shiny, we are literally throwing away the best parts for our health.
Teacher's Tip: Brown rice is "Vitamin-rich" rice.
Exam Tip: Mention the specific disease (Beri-beri) and vitamin (Vitamin B) involved.

MICROORGANISMS AND DISEASES

I. Multiple choice questions. Tick (✓) the correct choice:

1. Which of the following diseases is spread through coughing and sneezing?
1. Diphtheria
2. Hepatitis
3. Tetanus
4. Polio

Answer: 1. Diphtheria
Diphtheria is a serious infection that usually affects the mucous membranes of your nose and throat. It spreads through the air when people share breath or cough near each other.
Teacher's Tip: Diphtheria is a "Respiratory" threat.
Exam Tip: Group diseases by how they travel (air, water, touch).

2. Which of the following diseases is transmitted by a carrier?
1. Dengue
2. Tetanus
3. Hepatitis
4. Common cold

Answer: 1. Dengue
Dengue fever cannot move on its own; it needs a carrier, which is the Aedes mosquito. The mosquito carries the virus from an infected person's blood to a healthy person.
Teacher's Tip: Carrier = Vector.
Exam Tip: Link Dengue to its specific carrier (mosquito) for extra points.

3. Which of the following diseases is spread through infected rats?
1. Hepatitis
2. Dengue
3. Plague

Answer: 3. Plague
The plague is a bacterial infection that was famously carried by the fleas that lived on rats. This disease caused massive pandemics in history, such as the "Black Death" in Europe.
Teacher's Tip: Rats and fleas brought the plague to history books.
Exam Tip: Plague is the classic historical example of an animal-borne epidemic.

4. Which of the following is a non-infectious disease?
1. Cholera
2. Thypoid
3. Diabetes
4. Plague

Answer: 3. Diabetes
Diabetes is a chronic condition that occurs when the pancreas doesn't produce enough insulin. It's not caused by a germ, so you can't "catch" it from someone else.
Teacher's Tip: Non-infectious diseases are internal "glitches" in your body.
Exam Tip: Identify the cause of each disease to see which one is not a germ.

5. A disease spread by the bite of a mad dog is
1. Rabies
2. Plague
3. Polio
4. Measles

Answer: 1. Rabies
Rabies is a virus found in the saliva of infected mammals like dogs. It travels up the nerves to the brain, which is why a bite is so dangerous.
Teacher's Tip: Stay away from stray animals to stay safe from Rabies.
Exam Tip: Rabies is a viral disease specifically associated with animal bites.

II. Define the following:

1. Pathogen:
Answer: The microbes that cause disease are called pathogens. Example: Bacteria, virus, etc.
Pathogens are like tiny "unwanted guests" that enter your body and start making trouble. Each type of pathogen has a different way of attacking your cells and causing symptoms.
Teacher's Tip: Pathogen = Disease-causing germ.
Exam Tip: Always give an example like "Bacteria" in your definition.

2. Vector:
Answer: A vector is an organism that carries disease causing microbes (pathogens) from one host to another. They are the carriers of infection. Example: Mosquito, housefly, etc.
Vectors are essential for many diseases to move through a community. Without the mosquito, for example, the malaria parasite would have no way to reach its next victim.
Teacher's Tip: Vectors are "living delivery trucks" for germs.
Exam Tip: Differentiate between the "pathogen" (the germ) and the "vector" (the carrier).

3. Droplet infection:
Answer: Droplet infection is an infection transmitted from one individual to another by droplets of saliva or nasal moisture during coughing, sneezing, speaking and spitting.
These droplets are heavy enough that they usually fall to the ground within a few feet. However, if you are close enough to breathe them in, the germs can enter your system instantly.
Teacher's Tip: Catch your cough in your elbow to stop droplets!
Exam Tip: Use the words "saliva" or "nasal moisture" in your definition.

4. Infectious diseases:
Answer: The diseases which spread from an infected person to a healthy person through air, water, foQd, soil or physical contact are called communicable diseases. Example: Common cold, chickenpox, etc.
These diseases are caused by external agents that "invade" your body. Because the cause is external, these diseases can often be prevented through good hygiene and vaccination.
Teacher's Tip: Infectious diseases are "Catchable" diseases.
Exam Tip: List the modes of transmission (air, water, etc.) to get full marks.

III. Mention the causal organisms of the following diseases:

1. Cholera
2. Tuberculosis
3. Common cold
4. Chickenpox
5. Typhoid
6. Polio
7. Rabies
Answer:
1. Cholera - Bacteria
2. Tuberculosis - Bacteria
3. Common cold - Virus
4. Chickenpox - Virus
5. Typhoid - Bacteria
6. Polio - Virus
7. Rabies - Virus
Knowing whether a disease is bacterial or viral is the first thing a doctor needs to know. Bacterial infections can be killed by antibiotics, but viral ones usually have to be fought off by your own immune system.
Teacher's Tip: Bacteria and Viruses are like different types of "enemy armies."
Exam Tip: Make a list of these pairs and review them often.

IV. Answer the following questions:

Question 1: What are communicable diseases? Name three such diseases.
Answer: Diseases which spread from an infected person to a healthy person are called communicable or infectious diseases. These diseases are caused through infections by microbes called pathogens. Example: Cholera, typhoid, cold, malaria, AIDS.
These diseases travel through various pathways to reach new victims. Staying away from sick people and keeping your hands washed are the best ways to avoid them.
Teacher's Tip: Communicable = Spreadable.
Exam Tip: Be sure to name three distinct examples as requested.

Question 2: List the different ways by which communicable diseases are transmitted.
Answer: Communicable diseases are transmitted broadly by two modes:
1. Direct transmission: It is by
(a) Direct contact: From skin to skin. Examples: eye infection (conjunctivitis), skin diseases, etc.
(b) Droplet infection: From droplet of saliva or nose during cough, sneezing, speaking and spitting. Examples: Tuberculosis (TB), common cold, whooping cough, influenza.
(c) Contact with soil. Example: mycosis, tetanus.
(d) Inoculation into skin: Microbes may inoculate directly into skin. Examples: Rabies virus is inoculated by dog bite, hepatitis B virus is inoculated through contaminated needles and syringes.
2. Indirect transmission: It is by
(a) Transmission of microbes through water and food (vehicle borne transmission). Examples: typhoid, cholera, polio, food poisoning, diarrhoea etc.
(b) Transmission by blood. Examples: Hepatitis B and malaria.
(c) Transmission of microbes by an arthropod/living carrier (vector borne). Examples: malaria, dengue are transmitted by mosquito, typhoid, cholera are transmitted by housefly, plague is transmitted by rat flea, etc.
(d) Transmission through fomites: Fomites include soiled clothes, towel, cups, spoon, toys, etc. Examples: diptheria, eye and skin infection.
(e) Transmission through unclean hands. Examples: typhoid, intestinal parasites.
(f) Air borne transmission. Examples: epidemic typhus.
The way a disease spreads determines how we stop it. For example, we wear masks for droplet diseases, but we boil water for vehicle-borne ones like cholera.
Teacher's Tip: Direct = Touching; Indirect = Through something else.
Exam Tip: Use the broad categories "Direct" and "Indirect" to organize your long answer.

Question 3: Differentiate between communicable and non-communicable diseases.
Answer:
Communicable diseases
1. Diseases which spread from one person to another.
2. These are also called as infectious diseases.
3. These diseases are caused by microbes called pathogens.
4. Examples : AIDS, cholera, cold, mumps, typhoid etc.
Non-communicable diseases
1. Diseases which do not spread from person to person and remain confined to the diseased person.
2. These are also called as non-infectious diseases.
3. These diseases are not caused by microbes.
4. Examples : allergy, diabetes, anaemia, etc.
Communicable diseases are like "visiting" germs that cause trouble, while non-communicable diseases are "internal" problems with how the body is built or maintained. One needs isolation or cleaning to prevent, while the other needs lifestyle or medical management.
Teacher's Tip: Can I catch this from a hug? If yes, it's communicable!
Exam Tip: Differentiating point-by-point in a table is best for full marks.

DISEASES DUE TO MALFUNCTIONING OF BODY ORGANS, FIRST AID MEASURES AND HYGIENE

I. Multiple choice questions. Tick (✓) the correct choice:

1. Malfunctioning of pancreas causes
1. diabetes
2. arthritis
3. cataract
4. goitre

Answer: 1. diabetes
The pancreas is responsible for making insulin, a hormone that manages sugar in your blood. If it malfunctions, your blood sugar levels can become dangerously high.
Teacher's Tip: Think of the pancreas as your body's "Sugar Manager."
Exam Tip: Link the organ (Pancreas) to the hormone (Insulin) and the disease (Diabetes).

2. First vaccine was produced by
1. Pasteur
2. A. Fleming
3. Jenner
4. Robert Hooke

Answer: 3. Jenner
Edward Jenner's work in the late 1700s laid the foundation for modern medicine. He used cowpox to protect people from the much more deadly smallpox virus.
Teacher's Tip: Edward Jenner was the first "Vaccine Hero."
Exam Tip: Alexander Fleming discovered antibiotics, not vaccines—don't mix them up!

3. Cataract is a disease of the
1. heart
2. eye
3. kidney
4. pancreas

Answer: 2. eye
As people get older, the lens inside their eye can become cloudy and opaque. This block of light is called a cataract and causes vision to become blurry.
Teacher's Tip: Think of "looking through a frosted window."
Exam Tip: Cataract is a degenerative disease because it often happens as we age.

II. Fill in the blanks:
1. The disease caused by the bite of a mad dog is rabies.
2. Diseases of heart and kidney are due to malfunctioning of body organs.
3. Uremia is caused due to the malfunctioning of kidney.

Answer: Fill in the blanks with the bold words as shown above.
Rabies is a critical viral infection that animal bites can pass to humans. Malfunctioning diseases happen when an organ, like the kidney, can no longer filter toxins out of the blood correctly.
Teacher's Tip: Kidneys are the "Filters" of your body.
Exam Tip: "Uremia" comes from the word "Urine"—it's about waste staying in the blood.

III. Find the odd one out, giving reasons:
Diabetes, arthritis, cataract, obesity.

Answer: Obesity: Obesity is the odd one out as it is caused by imbalance in diet (over-nutrition) while the rest three are the diseases due to malfunctioning of body organs.
Diabetes (pancreas), Arthritis (joints), and Cataracts (eye lens) are all about body systems failing to work right. Obesity is primarily a nutritional problem caused by intake exceeding energy use.
Teacher's Tip: One is about "Too much food," the others are about "Broken parts."
Exam Tip: Be sure to mention "imbalance in diet" for your obesity reason.

IV. Define the following:

1. Vaccination:
Answer: Vaccination is a method of making the body immune to a particular disease by injecting killed or weakened disease causing microbe into a body to stimulate the formation of antibodies and develop immunity to that disease causing microbe.
It essentially gives your immune system a "practice target" to shoot at. This ensures that if the real germ arrives later, your body is already armed and ready to fight.
Teacher's Tip: Vaccination = Training for your immune system.
Exam Tip: Include the words "antibodies" and "immunity" in your definition.

2. Immunisation:
Answer: Immunisation is body’s natural defence mechanism which acts by producing antibodies against the antigens infecting the body.
This is the state of being protected from a disease. You can become immune naturally by having the disease once, or safely through a vaccine.
Teacher's Tip: Immunity is like a "Super Shield" for your health.
Exam Tip: Connect "Immunisation" to "Antibodies."

3. Immunity:
Answer: The ability of an organism to resist and overcome infection is called immunity.
Immunity is your body's overall strength against all kinds of invaders. A healthy lifestyle with good food and exercise helps keep your general immunity high.
Teacher's Tip: High immunity means you don't get sick easily.
Exam Tip: Use the word "resist" in your definition.

4. Vaccine:
Answer: A vaccine is a biological preparation of a weakened or killed pathogen (disease causing microbes) which stimulates the formation of antibodies and develops immunity against a particular disease.
A vaccine is the actual "medicine" or liquid that is used during the vaccination process. It carries the specific message that your body needs to learn how to fight a germ.
Teacher's Tip: The vaccine is the "message," vaccination is the "delivery."
Exam Tip: Specify "weakened or killed" microbes in your definition.

5. Pathogen:
Answer: Any organism that is capable of causing disease is called a pathogen. Examples: bacteria, virus or other microorganism.
Pathogens are specialized biological disruptors that thrive by invading other living things. Their presence triggers your immune system to start producing defenses like fever.
Teacher's Tip: Pathogens are the "villains" of the microscopic world.
Exam Tip: Always include an example of a type of microorganism.

6. Atherosclerosis:
Answer: Atherosclerosis is a disease caused by the malfuntioning of heart wherein the arterial walls get hardened and thickened, reducing the flow of blood and raising the blood pressure.
This hardening is usually caused by eating too much fatty food over many years. Because the arteries are less flexible, the heart has to work much harder to pump blood through them.
Teacher's Tip: Atherosclerosis is "Artery Hardening."
Exam Tip: Connect this disease specifically to "heart" and "circulatory system" health.

V. Answer the following questions:

Question 1: Write, in brief, about the following: (a) Fever, (b) Allergy, (c) First-aid measures in case of cuts, burns, bites and stings.
Answer:
(a) Fever: Fever is the most common symptom of an infection in the human body. The body temperature rises above the normal i.e., 37°C (98.6°F). Fever might be associated with pain in the body, headache and tiredness. Rest, light diet, fluids and medicines help in reducing fever.
(b) Allergy: Allergy is an excessive sensitivity of the human body to some substances which are otherwise harmless. The allergens include dust, pollen grains, spores, furs, etc. Asthma and hay fever are examples of allergies. Rashes, itching, wheezing and sneezing are common symptoms of allergy.
(c) First-aid in case of cuts: Cut area should be cleaned and washed with warm water. Foreign matter, if any, should be removed. Wound area be raised above the heart level and bandage to be put after the blood flow stops.
First-aid in case of burns: Hold the burnt area under cold running water in first and second degree burns for 15 minutes. Wash with soap and leave uncovered. Give the tetanus injection. In case of third-degree bums, cover the burnt with dry, sterile dressing and contact the emergency medical services.
First-aid in case of bites: Hold the bite area under cool running water for 15 minutes. Wash with soap and water. Rinse again. Dry the area, elevate the bite area above the heart level for 8 hours and give a tetanus injection. In case of a snake bite, run water over the bite, rub powdered potassium permanganate and put a piece of cloth tightly around the area to prevent the poison from reaching heart and other body parts.
First-aid in case of stings: Remove the sting with tweezers. Wash the area with soap and cold water, apply oil or vaseline, cover with sterile gauze. If swelling, apply ice. Keep the stung area above the heart.
First aid is the immediate care given to an injured person before professional medical help arrives. Doing the right thing in those first few minutes can stop a minor injury from becoming a major emergency.
Teacher's Tip: Tetanus shots are important for almost any skin-breaking injury.
Exam Tip: Use the specific temperature 37°C when defining fever for full marks.

Question 2: What would you do to lead a healthy life?
Answer: Personal hygiene is very important to lead a healthy life. It can be done by:
1. Proper diet: Balanced diet is very important.
2. Sleep: Adequate sleep of 6-8 hours a day.
3. Regular exercise: Sufficient physical activity.
4. Cleanliness: Keeping the body clean to prevent infections.
5. Proper lifestyle: Junk foods, long hours of table work, late night sleeps etc. should be avoided to lead a healthy life.
Leading a healthy life is about making good choices every day for your mind and body. Consistency in these habits builds a strong immune system that can fight off diseases naturally.
Teacher's Tip: Health is wealth—start these habits while you are young!
Exam Tip: Mention "Balanced diet" and "Physical activity" as your top two points.

Question 3: What steps would you take to prevent and control diseases?
Answer: Prevention and control of diseases can be done by:
1. Proper sanitation.
2. Provision of safe and clean water supply in adequate quantity.
3. Spray of insecticides to prevent mosquito breeding.
4. Personal hygiene which includes proper diet, sleep, regular exercise, cleanliness and healthy lifestyle.
5. Immunisation (vaccination).
6. Health education.
Preventing a disease is always easier and cheaper than curing one after it has started. These steps combine public health measures (like clean water) with individual actions (like getting vaccinated).
Teacher's Tip: Prevention is better than cure.
Exam Tip: Include "Health education" as it helps people know how to stay safe.

Question 4: Mention the contributions of (i) Edward Jenner and (ii) Louis Pasteur.
Answer: (i) Edward Jenner was the first to develop the technique of vaccination in 1798.
(ii) Louis Pasteur established that many diseases were caused by microbes and he demonstrated the principle of immunisation, vaccines and antibodies.
These two scientists changed the world by proving that invisible germs were behind our biggest health threats. Their discoveries made it possible to wipe out diseases that used to kill millions of people.
Teacher's Tip: Jenner started it, and Pasteur explained how it worked.
Exam Tip: Connect "Jenner" to the "first vaccine" and "Pasteur" to the "germ theory."

Question 5: What is diabetes? What are the symptoms?
Answer: Diabetes is a disease caused by the malfunctioning of pancreas in the body. When enough insulin is not produced by pancreas, the sugar levels rise in the blood and urine. Symptoms of diabetes include excessive thirst, frequent urination at night, loss of weight and fatigue.
Normally, insulin helps the sugar in your blood enter your cells to be used as fuel. In diabetes, that sugar stays stuck in the blood, which eventually causes damage to the whole body.
Teacher's Tip: Diabetes is a "sugar management" problem.
Exam Tip: List at least three distinct symptoms for a high-scoring answer.

Question 6: What is atherosclerosis? Name the organs which are affected in this disease.
Answer: Atherosclerosis is a disease caused by the malfunctioning of circulatory system in the body. The arterial walls get hardened and thickened, reducing the flow of blood. This raises the blood pressure.
This disease primarily affects the heart and the major arteries that carry blood throughout the body. It is often caused by a lifestyle that includes high-fat foods and very little exercise.
Teacher's Tip: Think of it as "hardening of the pipes."
Exam Tip: Be sure to mention "heart" and "circulatory system" as the affected parts.

Question 7: How does vaccination prevent diseases?
Answer: A vaccine contains a killed or weakened disease causing microbe that is responsible for infection. Because the germ is killed, it cannot make the person sick. When a person receives a vaccine, the body reacts by producing antibodies in defence. The antibodies remain in the blood for long and destroys the germs of a particular disease. In other words, vaccines expose people safely to germs so that they can fight with the same germs in future against its specific disease.
Vaccination acts like a "fire drill" for your body's immune system. It teaches the body how to react perfectly so that it's ready if a real "fire" (infection) ever starts.
Teacher's Tip: Vaccines create "biological memory" in your blood.
Exam Tip: Use the phrase "stimulate antibody production" to explain how it works.

CHAPTER ASSIGNMENT

I. Which of the following statements are true (T) and which ones are false (F)? Mark T or F:

1. AIDS is caused by a bacterium.
Answer: False. AIDS is caused by a virus.

2. Sneezing is an example of droplet infection.
Answer: True.

3. Malaria is a vector-borne disease.
Answer: True.

4. Atherosclerosis is a disease of the liver.
Answer: False. Atherosclerosis is a disease of the heart.

5. Filariasis is caused by worms.
Answer: True.

Follow the True/False and corrections provided above.
These statements test your fundamental understanding of disease causes. For example, knowing that atherosclerosis affects the heart and not the liver is a key anatomical fact.
Teacher's Tip: Check your notes to ensure you know which germ causes which disease.
Exam Tip: When a statement is false, always write the correct version to show your knowledge.

II. Give differences between the following:
First degree burn and second degree burn.
Answer:
First degree burn
1. It effects the skinsoutermost layer.
2. It is less severe.
3. There are no blisters. Just redness and swelling.
4. This is also called a superficial bum.
5. They are dry.
6. They heal on their own in a week or so.
7. Example: Ordinary sunburn.
Second degree burn
1. It effects epidermis and dermis of the skin.
2. It is more severe and painful.
3. The skin becomes red and has blisters.
4. This is also called as partial thickness bum.
5. They are moist.
6. They might need medical attention and heal in 2-3 weeks.
7. Example: Blisters formed by hot oil accidentally.
A first-degree burn only touches the surface, but a second-degree burn goes deeper and damages the underlying tissue. Blisters are the most obvious sign that a burn has reached the second degree.
Teacher's Tip: Blisters = Second Degree.
Exam Tip: Use a comparative table format for differentiation questions.

III. Answer the following questions:

Question 1: Give the first aid measures in case of second degree burns.
Answer: First-aid in case of second degree bums:
1. Hold the burnt area under cold running water for 15 minutes.
2. Do not break the blisters.
3. Wash the area with mild soap and water.
4. Dry and put an antibiotic oinment.
5. If blisters have not broken open, leave the area uncovered.
6. If blisters have broken open, bandage is needed.
The main goal is to cool the area and prevent infection. Breaking a blister is dangerous because it exposes the raw, sensitive skin underneath to germs in the air.
Teacher's Tip: Never pop a blister—it's your body's shield.
Exam Tip: Be sure to include the "15 minutes" cooling time for a complete answer.

Question 2: Name three commonly used vaccines.
Answer: Three commonly used vaccines are:
1. BCG for tuberculosis.
2. Salk vaccine for polio.
3. DPT for diptheria, pertussis (whooping cough) and tetanus.
These vaccines are usually given to babies and young children to build their immunity early. They have helped nearly eliminate some of these dangerous diseases from our world.
Teacher's Tip: DPT is a "Combo" vaccine that protects against three things at once!
Exam Tip: Know what each acronym stands for (e.g., BCG for TB).

Question 3: How vaccination helps to prevent diseases?
Answer: A vaccine contains a killed or weakened disease causing microbe that is responsible for infection. Because the germ is killed, it cannot make the person sick. When a person receives a vaccine, the body reacts by producing antibodies in defence. The antibodies remain in the blood for long and destroys the germs of a particular disease. In other words, vaccines expose people safely to germs so that they can fight with the same germs in future against its specific disease.
Vaccines essentially "trick" your body into thinking it is under attack by a weak germ. Because the body thinks it's a real attack, it builds a powerful army of antibodies that stay on guard for years.
Teacher's Tip: Think of a vaccine as a "smart training program" for your blood.
Exam Tip: Emphasize that the microbe in the vaccine is "killed or weakened."

Question 4: Why should you not allow water to stagnate near your house?
Answer: We should not allow water to stagnate near our house because:
1. Stagnant water is a breeding place for several mosquitoes which are carriers of many diseases like malaria and dengue.
2. It starts growing alga, etc. and stinks and rots the ground.
Still water provides the perfect environment for mosquito larvae to grow safely. By emptying old tires, pots, and puddles, we remove their "nursery" and reduce the number of mosquitoes around us.
Teacher's Tip: No stagnant water = No mosquito nurseries.
Exam Tip: Link "stagnant water" to "mosquito breeding" for full marks.

IV. Crossword Puzzle
DOWN
1. A disease caused due to the bite of a mad dog. (6)
2. Kwashiorkor and marasmus are caused due to the deficiency of this food component. (7)
3. A disease causing bleeding gums. (6)
ACROSS
4. A disease due to deficiency of vitamin D. (7)
5. Diabetes is caused due to deficiency of this hormone. (7)
6. The deficiency of this mineral causes anaemia. (4)
Answer:
DOWN:
1. Rabies
2. Protein
3. Scurvy
ACROSS:
4. Rickets
5. Insulin
6. Iron
Crossword terms reinforce the basic vocabulary of this chapter. For example, "Iron" being the cause of anaemia is a fundamental mineral deficiency link.
Teacher's Tip: These six words are the core concepts of this chapter!
Exam Tip: Cross-check the number of letters in the word with the number in parentheses.

SOME MORE USEFUL QUESTIONS

Question 1: Obesity can lead to many problems. Name them.
Answer: Obesity can lead to heart disease, high blood pressure and diabetes.
Carrying excess weight puts extra strain on every organ in your body, especially the heart which must pump blood further. Over time, this strain can cause chronic conditions that last a lifetime.
Teacher's Tip: Staying active is the best medicine for obesity.
Exam Tip: List all three problems (Heart, BP, Diabetes) for a high-scoring answer.

Question 2: What does deficiency of carbohydrates lead to?
Answer: Deficiency of carbohydrates leads to: Body weakness. Loss of stamina.
Carbohydrates are the main "fuel" that our muscles and brain use to function. Without them, you will feel constantly tired and won't have the energy to run or study.
Teacher's Tip: Carbs are your body's "gasoline."
Exam Tip: Use the words "weakness" and "stamina" to describe the effect.

Question 3: What are antibiotics?
Answer: Antibiotics are chemical substances that kill or stop the growth of microbes, thereby helping the body to fight diseases. Eg. penicillin.
These medicines are designed to target specific structures in bacteria without harming human cells. They have saved countless lives since they were first discovered.
Teacher's Tip: Antibiotics only work on bacteria, not viruses!
Exam Tip: Always provide an example like "Penicillin" in your definition.

Question 4: Who discovered the first antibiotic?
Answer: The first antibiotic, Penicillin, was discovered by Alexander Fleming.
He found it by accident when he noticed that a certain mold prevented bacteria from growing in a petri dish. This observation revolutionized medicine and made bacterial infections curable.
Teacher's Tip: Alexander Fleming is the "Antibiotic Pioneer."
Exam Tip: Don't confuse "Fleming" (antibiotics) with "Jenner" (vaccines).

Question 5: Give examples of diseases caused by:
1. Fungus
2. Insect bite
3. Ingesting infected food and water
4. Pollution/allergy
5. Worms
Answer:
1. Food poisoning and ringworm.
2. Malaria and dengue.
3. Cholera and typhoid.
4. Asthma and hay fever.
5. Ascariasis and filariasis.
Each of these categories represents a different way that our health can be compromised by our environment. Understanding the source (like a worm or a fungus) helps us know how to avoid the disease.
Teacher's Tip: "Worms" are often called parasites.
Exam Tip: Matching the "source" to the "disease" is a common exam task.

Question 6: Name two diseases caused by animal bites.
Answer: Rabies by dog bite. Snake poisoning by snake bite.
Animal bites introduce pathogens or toxins directly into the tissues or blood. While rabies is a slow-acting virus, snake venom can work extremely quickly and requires immediate first aid.
Teacher's Tip: Animal saliva and venom are the "delivery systems" here.
Exam Tip: Name both "Rabies" and "Snake poisoning" for a complete answer.

Question 7: Name few contact infections.
Answer: Skin diseases, lice, chicken pox, conjunctivitis.
Contact infections spread when you touch an infected person or something they have used, like a towel or comb. Conjunctivitis is often called "pink eye" and is very easy to pass between students.
Teacher's Tip: Don't share personal items like hats or brushes!
Exam Tip: List at least three distinct infections for a full mark.

Question 8: What bad habits can lead to bad health?
Answer:
• Lack of personal hygiene.
• Lack of exercise.
• Addiction to fast food, drugs, tobacco, alcohol etc.
• Poor sanitation.
Our daily habits act as the foundation for our long-term health. Choosing good food and staying active are the easiest ways to keep your body working correctly as you grow up.
Teacher's Tip: Good habits are a "shield" for your body.
Exam Tip: Use terms like "personal hygiene" and "sanitation" in your list.

Question 9: Name few vectors and diseases caused by them.
Answer:
• Mosquito - malaria, dengue, filaria.
• Housefly - typhoid, cholera, polio.
• Sand fly - kala azar.
• Rat flea - plague.
Vectors are specialized carriers that help germs travel much further than they could on their own. For example, a flea can jump from a rat to a human, bringing the plague bacteria with it.
Teacher's Tip: Each vector has its own "favorite" disease.
Exam Tip: Create a table with "Vector" in one column and "Disease" in the other.

Question 10: Name the vitamin and mineral whose deficiency causes rickets.
Answer: Deficiency of calcium and vitamin D causes rickets.
Calcium is the building material for bones, and Vitamin D is the "worker" that helps the body use that material. Without both, a child's bones will be soft and may bend under their weight.
Teacher's Tip: Vitamin D and Calcium are "Best Friends" for your bones.
Exam Tip: Mention both the vitamin AND the mineral for full credit.

Question 11: Name the nutrient lacking in one’s diet if a person suffers from:
1. Haemorrhage
2. Dehydration
3. Paralysis
4. Tooth decay
5. Skin diseases
Answer:
1. Vitamin K
2. Sodium
3. Potassium
4. Vitamin D and fluorine
5. Vitamin B₂
Every nutrient has a unique biological role. For example, potassium is essential for your nerves and muscles to communicate, which is why a deficiency can lead to paralysis symptoms.
Teacher's Tip: Think of nutrients as "essential spare parts."
Exam Tip: Match each specific symptom to its correct missing nutrient.

Question 12: Who gave the ‘germ theory of disease’?
Answer: Louis Pasteur.
Pasteur proved that tiny, invisible organisms were responsible for food spoiling and for making people sick. This was a massive change from old ideas that said diseases were caused by "bad air" or "fate."
Teacher's Tip: Louis Pasteur "unmasked" the invisible germs.
Exam Tip: This is a very common history-of-science question.

Question 13: How can microorganisms enter our body?
Answer:
• Through the air we inhale.
• Through the water we drink.
• Through the food we eat.
• Through skin.
Pathogens use every available entrance to get inside us. Once inside, they look for warm, moist places like your throat or gut where they can start to reproduce.
Teacher's Tip: Your skin is your body's "main wall"—keep it clean!
Exam Tip: List the four main portals of entry (Air, Water, Food, Skin).

Question 14: What is conjunctivitis?
Answer: Conjunctivitis is a viral disease of the eye which is highly infections i.e., spreads from one person to another very fast.
It causes the white part of the eye to look pink or red because the small blood vessels are inflamed. It can also cause itching and a sticky discharge from the eyes.
Teacher's Tip: If your eyes are pink and itchy, see a doctor and wash your hands!
Exam Tip: Specify that it is "highly infectious" in your description.

Question 16: Name few diseases which are transmitted by air.
Answer: Common cold, chicket pox, tuberculosis, measles.
Airborne diseases can travel on tiny droplets when people talk or breathe. In crowded places, these germs move quickly between people, making air-borne illnesses very hard to stop.
Teacher's Tip: Good ventilation helps blow airborne germs away.
Exam Tip: List at least three distinct air-borne diseases.

Question 17: What are degenerative diseases? Why do they occur?
Answer: Diseases due to malfunctioning of body organs are called degenerative diseases. Malfunctioning of body organs occurs due to ‘wear and tear’ and ageing of body.
Just like an old machine might start to creak or fail, the human body can gradually break down over many decades. These diseases aren't caught from germs, but are a natural part of getting older.
Teacher's Tip: Degenerative = Wearing down.
Exam Tip: Mention "ageing" and "wear and tear" as the two primary causes.

Question 18: Name few diseases caused by malfunctioning of body organs.
Answer:
• Malfunctioning of pancreas causes diabetes.
• Malfunctioning of eyes causes cataract.
• Malfunctioning of bones cause arthritis.
• Malfunctioning of kidneys cause uremia.
• Malfunctioning of heart causes coronary heart disease and atherosclerosis.
Malfunctioning diseases are "internal" and often permanent once they start. They require ongoing medical management rather than a simple cure like an antibiotic shot.
Teacher's Tip: Each "broken" organ has its own specific disease name.
Exam Tip: Link at least three organs to their correct malfunctioning disease.

Question 19: Which body part produces insulin?
Answer: Islets of Langerhans present in pancreas produce the hormone insulin.
The Islets of Langerhans are tiny "islands" of specialized cells scattered throughout the pancreas. They monitor your blood sugar every second and release just the right amount of insulin.
Teacher's Tip: The pancreas is the "factory," and the Islets are the "machines" inside.
Exam Tip: Mention "Islets of Langerhans" for a more advanced and higher-scoring answer.

Question 20: What are coronary heart diseases?
Answer: Coronary heart diseases are diseases due to malfunctioning of heart wherein the blood supply to the heart muscles reduces leading to reduced supply of oxygen to it. This can lead to a temporary pain in the chest. Hardening of arteries which supply blood to the heart muscles cause this disease.
The heart is a muscle that needs its own supply of fresh oxygen to keep beating. If the "fuel lines" (coronary arteries) get blocked, the heart muscle starts to die, which is very dangerous.
Teacher's Tip: Coronary = "Related to the heart's own arteries."
Exam Tip: Explain that "reduced oxygen" is what causes the chest pain.

Question 21: Name a disease which causes opaque eye lens and hence blindness.
Answer: Cataract.
When the lens becomes opaque, it's like a white curtain has been pulled across the eye. Light can't get through to the retina, so the person cannot see anything.
Teacher's Tip: "Opaque" means light cannot pass through it.
Exam Tip: Cataract is the specific term for a cloudy lens.

Question 22: What is rabies?
Answer: Rabies is a viral disease caused by the bite of a rabid dog or monkey or rabbit. Saliva of the infected animal causes the rabies infection.
It is one of the deadliest viruses known and can be found in many wild mammals. Once symptoms start, it is almost impossible to cure, so early vaccination after a bite is vital.
Teacher's Tip: Rabies travels from "saliva" to "blood" to "brain."
Exam Tip: Mention "saliva" and "animal bite" in your definition.

Question 23: What are antibodies?
Answer: Antibodies are substances (proteins) which are produced by our body to attack the foreign bodies and they protect the host from disease.
Antibodies are shaped like little "Y"s and they latch onto germs to signal your white blood cells to destroy them. They are custom-built for each specific type of germ your body encounters.
Teacher's Tip: Antibodies are your body's "smart missiles."
Exam Tip: Use the term "proteins" and "defend/attack" in your answer.

Question 24: Fill in the blanks:
Answer:
1. Malfunctioning of kidneys can lead to accumulation of toxic substances in the body.
2. Lack of insulin may lead to diabetes.
3. A disease is opposite to health.
4. Intake of inadequate or excess food or unbalanced diet leads to malnutrition.
5. Diseases due to infection by microorganisms are called communicable diseases.
6. Louis Pasteur proved that microbes cause diseases.
7. Inflammation of joints result in arthritis.
Each blank summarizes a key concept from the chapter, such as the scientist who founded germ theory. Understanding these basic "Who/What/Where" links is the core of biology.
Teacher's Tip: Arthritis affects your "joints"—that's why they hurt!
Exam Tip: Be sure to match the organ to its specific malfunction (Kidney-Toxins).

Question 25: Give a brief note on body’s natural defence mechanism to overcome diseases.
Answer:
1. The skin acts as a barrier to the entry of microbes.
2. Tiny hair and mucous in the nose trap dust and microbes.
3. Digestive juices in the stomach kill microbes which enter the body.
4. White blood cells in the blood destroy the microbes.
5. Immune system produces antibodies against foreign particles.
Your body has several "layers" of defense, starting from the physical wall of your skin to the chemical weapons of your immune system. These systems work together 24/7 to keep you healthy without you even knowing it.
Teacher's Tip: Your skin is like a castle wall, and your WBCs are the soldiers.
Exam Tip: List at least four distinct defense layers for a comprehensive note.

Question 26: List few precautions taken to maintain personal hygiene and cleanliness.
Answer:
• Wash your hands before and after meals.
• Brush your teeth twice a day.
• Don’t keep long nails.
• Walking barefoot must be avoided.
• Waste food material and garbage should be thrown in bins and covered properly.
Hygiene is about simple, daily actions that keep pathogens away from your body. By doing these things, you significantly lower your risk of catching or spreading infectious diseases.
Teacher's Tip: "Clean hands, happy heart!"
Exam Tip: Provide a diverse list of habits (hands, teeth, surroundings) for the best marks.