Frank Brothers Solutions for ICSE Class 9 Biology Chapter 20 Health Causes Of Diseases

PAGE NO:191

Answer 1: (a) Disease is the stage when body or any part of it shows some disturbance in normal functions.
(b) Pathogen refers to any disease-causing organism.
(c) Infection refers to the pathological state resulting from the invasion of the body by pathogenic microorganisms.
(d) Incubation period refers to the period between exposure to an infection and the appearance of the first symptoms.
A disease essentially means the body is in a state of "dis-ease" or lack of comfort because its systems are not working correctly. The incubation period is like a waiting time where the germs are growing inside you before you actually feel sick.
Teacher's Tip: Think of a Pathogen as a "Passage to pain" because it carries the sickness into your body.
Exam Tip: Use the exact keywords like "invasion" and "pathological state" to get full marks for the definition of infection.

PAGE NO:192

Answer 2: 1. Communicable diseases are the diseases which spread by different organisms such as bacteria, virus and fungi. These are transmitted from one person to another. Example - Flu, malaria, syphilis.
2. Non-communicable diseases - These diseases are not transferred from one person to another. They are of different types like allergy, nutritional deficiencies, degenerated diseases, cancer and mental diseases. Example - Arthritis, hypertension
3. Epidemic diseases - These diseases spread rapidly and affect a large number of people at a time. Example - Spread of plague in Surat in 1994.
4. Sporadic diseases - This refers to a type when there are scattered individual cases of a disease.
Communicable diseases are like "shared" illnesses that travel through air, water, or contact, while non-communicable ones are "private" and stay with the individual. Epidemic diseases are very dangerous because they can make a whole city sick in just a few days.
Teacher's Tip: Remember 'C' for Communicable and 'C' for Catching - you can catch these from others!
Exam Tip: Always provide at least one specific example for each category to illustrate your understanding.

Answer 3: Pneumonia - Diplococcus pneumonia
Tetanus - Clostridium tetani
Whooping cough - Haemophilus pertussis
These scientific names tell us exactly which specific bacterium is responsible for making a person sick with these conditions. Many bacterial names are actually derived from the name of the disease they cause, making them easier to identify.
Teacher's Tip: Notice how the second part of the scientific name often sounds like the disease, such as "tetani" for Tetanus.
Exam Tip: Underline scientific names of organisms if you are writing them by hand to follow proper biological rules.

Answer 4: (i) Influenza - Symptoms - Symptoms begin with headache, cold, sneezing, nose clogging, pain in hands, feet and waist. Watery discharge from nose and eyes makes patient restless and weak. Method of treatment - Increased immunity is the best remedy. Penicillin, streptopenicillin and gamma globulin lower the effect of this disease. Eucalyptus oil should be applied on nose. During high fever, ice fermenting should be done as well as liquid food given.
(ii) Polio - Symptoms - Symptoms commence 7-12 days after infection. These include infection of throat and intestines, muscle stiffness in neck and back. Treatment - Vaccine of polio is more effective in children. Oral polio drops are also given to children.
Influenza, commonly known as the flu, affects your breathing and makes your whole body ache while your immune system fights it off. Polio is a much more serious viral infection that can lead to permanent muscle stiffness if not prevented by early vaccination.
Teacher's Tip: For Polio, remember "Drops for Tots" to recall the oral vaccine given to young kids.
Exam Tip: When describing symptoms, mention both the physical signs (like sneezing) and the internal feelings (like muscle stiffness).

Answer 5: Infectious diseases are the diseases which spread by different organisms such as bacteria, virus and fungi. These are transmitted from one person to another. Influenza is a highly infectious viral disease. This disease spreads quickly from one person to the next. The virus is transmitted from the patient to the other person while the patient is coughing, sneezing, laughing or speaking. This is also transmitted by contaminated towel and handkerchief.
Symptoms - Symptoms begin with headache, cold, sneezing, nose clogging, pain in hands, feet and waist. Watery discharge from nose and eyes makes patient restless and weak.
Method of treatment - Increased immunity is the best remedy. Penicillin, streptopenicillin and gamma globulin lower the effect of this disease. Eucalyptus oil should be applied on nose. During high fever, ice fermenting should be done as well as liquid food given.
Because influenza is viral, it travels in tiny droplets through the air when people talk or laugh. This is why it is so important not to share personal items like towels when someone is feeling sick.
Teacher's Tip: Use the "Hand-to-Hand" rule: Wash your hands to stop the "Infectious" spread.
Exam Tip: Be sure to distinguish between how a disease is "transmitted" (the way it travels) and its "symptoms" (how it feels).

Answer 6: (a) Tuberculosis: It is caused by Mycobacterium tuberculosis. It affects bones, intestine, brain and other organs. Symptoms include restlessness in the beginning, loss of appetite, pain in chest and increase in heart beat. Treatment includes taking medicines like P.A.S. and thioacetazone.
(b) Diptheria: It is a communicable disease caused by Corynebacterium diptheriae. In most of the people, this is caused by droplet infection, coughing and spitting. Symptoms are high fever, weakness and swelling in the throat. Patients should be treated with anti-toxin injection. Children should be vaccinated with DPT.
(c) Influenza: Influenza is a highly infectious viral disease. This disease spreads quickly from one person to the next. The virus is transmitted from the patient to the other person while the patient is coughing, sneezing, laughing or speaking. This is also transmitted by contaminated towel and handkerchief. Symptoms - Symptoms begin with headache, cold, sneezing, nose clogging, pain in hands, feet and waist. Watery discharge from nose and eyes makes patient restless and weak. Method of treatment - Increased immunity is the best remedy. Penicillin, streptopenicillin and gamma globulin lower the effect of this disease. Eucalyptus oil should be applied on nose. During high fever, ice fermenting should be done as well as liquid food given.
(d) Measles: It is a highly infectious viral disease. It usually affects children. Symptoms include - suddenly high fever, red eyes and oozing of water from eyes. Fever, cough and rashes appear on the third day. After 2 to 3 days temperature goes down. Treatment includes complete rest, clothes and towels should be washed in boiling water. Endomonstan B-vaccine is the best treatment.
(e) Malaria: This disease is caused by parasitic protozoa, Plasmodium. The disease is transmitted from one person to another by female anopheles mosquitoes. The symptoms are followed by high fever, temperature rises on alternate days. Sweating is followed by lowering of body temperature. Besides this patient feels headache, nausea and vomit. This disease is treated by medicines like chloroquine, deraprin, etc.
(f) Filaria: It is caused by filarial worm, Wuchereria bancrofti. This disease is transmitted by mosquito. Symptoms include - irritation, blockage of lymphatic ducts and fever. This disease can be treated with an arsenic medicine for adult worms.
These diseases range from those caused by bacteria and viruses to those carried by insects like mosquitoes. Understanding that mosquitoes act as "carriers" or vectors for Malaria and Filaria is key to preventing these diseases through netting and sprays.
Teacher's Tip: For Diphtheria, remember "D" for "Droplets" and "D" for "DPT vaccine."
Exam Tip: When writing about Malaria, explicitly state that it is the "female anopheles mosquito" specifically that spreads the disease.

Answer 7: The symptoms of diabetes insipidus are:

• Excessive urination, but urine does not contain sugar at all
• Increased frequency in urination
• Progressive weakness
• Increased appetite
• Loss of weight
• Excessive thirst

Diabetes insipidus is different from the common sugar diabetes because it involves a problem with how the body balances water. This leads to a constant feeling of being thirsty no matter how much water you drink.
Teacher's Tip: Think of "Insipidus" as "Insipid" or tasteless, because the urine doesn't have sugar.
Exam Tip: Do not confuse this with Diabetes Mellitus; emphasize that there is "no sugar in urine" for Diabetes Insipidus.

Answer 8: Diplococcus pneumonia, Clostridium tetani, Ascaris lumbricoides, Plasmodium species, HIV virus
This list represents a variety of biological invaders including bacteria, parasitic worms, protozoans, and viruses. Each of these pathogens has a unique way of entering the body and disrupting its normal functions.
Teacher's Tip: Group these by type: the first two are bacteria, the third is a worm, the fourth a protozoan, and the last a virus.
Exam Tip: Learn the spelling of "Ascaris lumbricoides" carefully, as it is a common scientific name in biology exams.

Answer 9: The main causes of human heart diseases are:

• Body overweight
• Birth defects of the heart
• Deposition of cholesterol resulting in arteriosclerosis
• Severe infections
• Excessive use of coffee, tobacco etc.
• Malfunctioning of some of the endocrine glands

Heart diseases can be caused by the choices we make, like diet and smoking, or things we are born with. Keeping a healthy weight and avoiding tobacco are the best ways to keep your heart pumping strong.
Teacher's Tip: Think of "Arteriosclerosis" as "Artery-is-closed" due to cholesterol buildup.
Exam Tip: List at least four distinct causes when answering a long-form question on heart health.

Answer 10: Full form of AIDS is Acquired Immuno Deficiency Syndrome. It is caused by Human Immunodeficiency virus (HIV). AIDS is transmitted in the following ways:
1. Sexual intercourse with the suffering from AIDS.
2. Transfusion of the AIDS infected blood.
3. New born child born from the infected mother.
AIDS is a very serious condition because the HIV virus attacks the body's own defense system, making it hard to fight off any other illness. It is only spread through direct contact with specific body fluids, not by casual touch or through the air.
Teacher's Tip: Remember the full form: Acquired (caught), Immuno Deficiency (weak defense), Syndrome (set of symptoms).
Exam Tip: Make sure to distinguish between HIV (the virus) and AIDS (the disease stage).

Answer 11: Degenerative diseases - Rheumatic

• Diabetes - Insulin
• AIDS - HIV virus
• Cholera - Bacterial disease
• Influenza - Viral disease
• Mosquito - Vector
• Elephantiasis - Filaria

This list matches diseases with their primary causes, treatments, or the way they travel. For example, a "vector" is like a tiny transport vehicle that carries germs from one person to another.
Teacher's Tip: Link "Insulin" directly to "Diabetes" as it's the key chemical the body lacks in that disease.
Exam Tip: These pairings are perfect for match-the-following or one-word answer sections.

Answer 12: (a) allergy (b) Plasmodium (c) virus, bacteria (d) caused by virus (e) Wuchereria bancrofti
These terms are the missing pieces for various scientific statements about how we get sick. They identify the specific microscopic life forms, like viruses and protozoans, that are responsible for common health issues.
Teacher's Tip: Remember that "Wuchereria" is the worm that causes the swelling in Elephantiasis.
Exam Tip: Be precise with spelling, especially for "Plasmodium" and "Wuchereria."

Answer 13: (a) Endemic disease: This disease is limited to a particular area, in which a small number of cases are always present. Eg. Yellow fever in certain African countries.
Pandemic disease: Here, the disease spreads from one country to another until one continent or more is affected. E.g. AIDS
(b) Sporadic disease: Here, there are scattered individual cases of a disease.
Epidemic disease: Here, the disease spreads rapidly and affects a large number of people.
(c) Infectious disease: These diseases are caused by pathogens. They spread from one person to another. Example - Influenza, cholera, malaria.
Non-infectious disease: These diseases are not caused by pathogens but result due to some other internal or external factors. They do not spread from one person to another. Example - Cancer, arthritis, hypertension.
(d) Congenital disease: These diseases are present right from birth. Example - Sickle cell anemia, diabetes, haemophilia.
Acquired disease: These diseases are generated after birth. Example - Influenza, cholera, cancer.
These comparisons show us how diseases differ in how they spread across the globe and when they first appear in a person's life. While some are with us from the day we are born, others are caught or developed as we grow up.
Teacher's Tip: 'Pan' in Pandemic means 'all' or 'everywhere' - think of a panorama view.
Exam Tip: When comparing, always use a table or clear bullet points to show the differences side-by-side.

Answer 14: (a) Typhoid, cholera, tetanus
(b) Viruses
(c) Rabies
(d) Filariasis, Ascariasis
(e) Arthritis, diabetes
These groups of diseases are classified by their type, such as bacterial, viral, or non-communicable. Group (a) consists of bacterial infections, while group (e) contains chronic conditions that you cannot catch from someone else.
Teacher's Tip: Categorizing diseases helps you remember their specific treatments more easily.
Exam Tip: If asked to group diseases, look for common causes like "all these are caused by worms" or "all these are bacterial."

Answer 15:
(a) False
(b) False
(c)
True
(d) True
(e) False
(f) True
True and False questions test your ability to distinguish scientific facts from common myths about health. For instance, knowing that not all diseases are contagious is a vital piece of medical knowledge.
Teacher's Tip: Read the statement twice; sometimes one small word like "never" or "always" makes it False.
Exam Tip: If a statement is False, try to mentally correct it to reinforce your actual knowledge.

Answer 16: (i) (a) Diabetes
(ii) (d) Cholera
(iii) (b) filarial
(iv) (b) Smallpox
(v) (d) yellow fever
(vi) (c) Uncontrolled division of cells
These multiple-choice answers highlight key characteristics and examples of different medical conditions. For example, the definition of cancer is fundamentally the uncontrolled growth of cells in the body.
Teacher's Tip: "Uncontrolled division" is the scientific way of saying the body's cells won't stop making copies of themselves.
Exam Tip: In MCQs, use the process of elimination to remove obviously wrong answers first.