Test: Why Do We Fall Ill- 2 - Class 9 MCQ

Why antibiotics do not work against viral infections:
1. Viruses live only inside host cells:
- Antibiotics target and kill bacteria, which are living organisms.
- Viruses, on the other hand, are not considered living organisms as they cannot reproduce or carry out metabolic processes on their own.
- Viruses rely on host cells to replicate and multiply.
2. Viruses do not have biochemical pathways of their own:
- Antibiotics typically work by disrupting specific biochemical pathways or processes in bacteria.
- Viruses do not have these pathways of their own, making them unaffected by antibiotics.
3. Viruses are resistant to antibiotics:
- Antibiotics are designed to target specific structures or processes in bacteria.
- Viruses have different structures and mechanisms, which make them resistant to antibiotics.
4. The protein coat of viruses acts as a barrier to the antibiotics:
- Viruses have a protein coat that surrounds their genetic material.
- This protein coat acts as a barrier to antibiotics, preventing them from reaching and affecting the viral genetic material.
In conclusion:
- Antibiotics are not effective against viral infections because viruses live inside host cells, lack biochemical pathways, are resistant to antibiotics, and have a protein coat that acts as a barrier.
- Antiviral medications specifically target the unique characteristics of viruses and are used to treat viral infections.

Answer:
The correct answer is D: Influenza. Influenza is not a bacterial disease, but rather a viral infection caused by the influenza virus.
Explanation:
Bacterial diseases are caused by bacteria, while viral diseases are caused by viruses. In this question, we are asked to identify the disease that is not caused by bacteria. Here's a breakdown of the options:
A. Cholera: Cholera is caused by the bacterium Vibrio cholerae and is characterized by severe diarrhea and dehydration.
B. Tuberculosis: Tuberculosis is caused by the bacterium Mycobacterium tuberculosis and primarily affects the lungs, but can also affect other parts of the body.
C. Anthrax: Anthrax is caused by the bacterium Bacillus anthracis and can affect humans and animals. It can be transmitted through contact with infected animals or their products.
D. Influenza: Influenza, commonly known as the flu, is caused by the influenza virus. It is a highly contagious viral infection that affects the respiratory system.
Therefore, the correct answer is D: Influenza, as it is not a bacterial disease.

The set of diseases which spread through sexual contact as well as through placenta to the foetus are:
- AIDS (Acquired Immunodeficiency Syndrome): AIDS is caused by the Human Immunodeficiency Virus (HIV) and can be transmitted through sexual contact, blood transfusion, sharing needles, and from mother to child during pregnancy, childbirth, or breastfeeding.
- Syphilis: Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum. It can be transmitted through sexual contact, including vaginal, anal, and oral sex, as well as through placenta to the foetus during pregnancy.
Other options:
- Malaria: Malaria is not typically transmitted through sexual contact or from mother to child during pregnancy. It is primarily spread through the bite of infected mosquitoes.
- Cancer: Cancer is not a communicable disease that can be transmitted through sexual contact or from mother to child during pregnancy. It is a result of abnormal cell growth in the body.
Therefore, the correct answer is B: AIDS and Syphilis as these are the diseases that can spread through sexual contact as well as from mother to child during pregnancy.

Immunisation/Vaccination started with:
- E. Jenner: Edward Jenner is credited with the discovery of the smallpox vaccine, which is considered the first successful vaccine. He observed that milkmaids who had contracted cowpox, a milder disease, seemed to be immune to smallpox. In 1796, he conducted an experiment where he inoculated a young boy with cowpox to protect him from smallpox. This marked the beginning of immunisation.
- L. Pasteur: Louis Pasteur made significant contributions to the field of immunisation, but he did not start it. He developed vaccines for diseases like rabies and anthrax, using weakened or killed pathogens.
- A. Fleming: Alexander Fleming discovered penicillin, an antibiotic used to treat bacterial infections. While antibiotics are crucial for treating infections, they are not vaccines or immunisation methods.
- J.E. Salk: Jonas Salk developed the first effective polio vaccine in the 1950s. Although his vaccine was a major breakthrough in preventing polio, it was not the beginning of immunisation.
In conclusion: Edward Jenner (Option C) is credited with starting immunisation/vaccination with his discovery of the smallpox vaccine.

Answer:
The disease that is not transmitted by mosquitoes is Pneumonia.
Explanation:
Pneumonia is an infection that affects the lungs and is caused by bacteria, viruses, or fungi. It is not transmitted by mosquitoes. Here is a detailed explanation of the other diseases mentioned in the options:
Dengue:
- Dengue is a viral infection transmitted by the Aedes mosquito.
- It can cause high fever, severe headache, joint and muscle pain, and in severe cases, it can lead to dengue hemorrhagic fever or dengue shock syndrome.
- The Aedes mosquito primarily breeds in stagnant water sources.
Malaria:
- Malaria is a parasitic disease transmitted by female Anopheles mosquitoes.
- It is caused by the Plasmodium parasite and can cause symptoms such as fever, chills, headache, and fatigue.
- Malaria is a major public health concern in many tropical and subtropical regions.
Brain Fever or Encephalitis:
- Encephalitis refers to inflammation of the brain.
- While mosquitoes can transmit some viruses that can cause encephalitis, such as the West Nile virus or Japanese encephalitis virus, it is not a specific disease transmitted solely by mosquitoes.
- Encephalitis can also be caused by other factors such as bacterial or fungal infections.
Therefore, out of the given options, Pneumonia is the disease that is not transmitted by mosquitoes.

Cells involved in fighting against infections:
- White blood cells: White blood cells, also known as leukocytes, are the primary cells involved in fighting against infections. They play a crucial role in the immune response by recognizing and destroying pathogens such as bacteria, viruses, and fungi.
- Red blood cells: Red blood cells are responsible for carrying oxygen to various tissues and organs in the body. While they do not directly fight against infections, they are essential for maintaining a healthy immune system by providing oxygen to immune cells.
- Platelets: Platelets are involved in blood clotting and wound healing. Although they do not directly fight against infections, they play a crucial role in preventing excessive bleeding, which can occur as a result of infection-related injuries.
- Liver cells: Liver cells, or hepatocytes, are primarily responsible for detoxifying the blood and producing various proteins, including those involved in the immune response. While they indirectly support the immune system, they are not directly involved in fighting against infections.
In conclusion, the cells of our body that are directly involved in fighting against infections are white blood cells. Red blood cells and platelets indirectly support the immune system, and liver cells play a role in supporting the immune response but are not directly involved in fighting infections.

Answer:
The disease caused by protozoans is Malaria.
Explanation:
Protozoans are single-celled organisms that can cause various diseases in humans. Malaria is one such disease caused by the protozoan parasite called Plasmodium. Here is a detailed explanation of Malaria as a disease caused by protozoans:
- Malaria:
- Malaria is a life-threatening disease transmitted through the bite of infected female Anopheles mosquitoes.
- The protozoan parasite Plasmodium is responsible for causing malaria in humans.
- There are several species of Plasmodium that can cause malaria, with the most common being Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, and Plasmodium ovale.
- When an infected mosquito bites a person, the parasite is transmitted into their bloodstream.
- The parasites then travel to the liver and multiply before infecting red blood cells.
- The symptoms of malaria include fever, headache, chills, vomiting, and muscle aches.
- If left untreated, malaria can lead to severe complications and even death.
- Malaria is prevalent in tropical and subtropical regions, particularly in Africa, Asia, and Latin America.
- Prevention and control measures include the use of insecticide-treated bed nets, indoor residual spraying, antimalarial medications, and mosquito control programs.
In conclusion, Malaria is the disease caused by protozoans, specifically the Plasmodium parasite. It is essential to understand the causes and symptoms of diseases to prevent and effectively treat them.

Ascara lumbricoides causes damage to our intestine.

• Ascara lumbricoides is a parasitic roundworm that infects the human intestine.


• It is one of the most common parasitic infections worldwide.


• When a person ingests the eggs of Ascara lumbricoides through contaminated food, water, or soil, the eggs hatch in the small intestine.


• The larvae then penetrate the intestinal wall and migrate to the liver, heart, and lungs through the bloodstream.


• After reaching the lungs, the larvae are coughed up and swallowed, returning to the intestine.


• In the intestine, the larvae mature into adult worms and can reach lengths of up to 30 cm.


• The adult worms attach themselves to the intestinal wall and feed on the host's digested food, causing inflammation and damage to the intestine.


• This damage can lead to various symptoms including abdominal pain, diarrhea, vomiting, and malnutrition.


• In severe cases, Ascara lumbricoides infection can cause intestinal obstruction, appendicitis, and pancreatitis.


• Treatment for Ascara lumbricoides infection usually involves medication to kill the worms and alleviate symptoms.


• Prevention measures include proper hygiene practices, such as washing hands before meals and after using the toilet, and avoiding consumption of contaminated food and water.

In conclusion, Ascara lumbricoides causes damage to our intestine by attaching themselves to the intestinal wall and feeding on the host's digested food. This can lead to various gastrointestinal symptoms and, in severe cases, complications such as intestinal obstruction. Proper hygiene practices and avoiding consumption of contaminated food and water are important for prevention.

Most skin infections are caused by fungi.
There are several types of microorganisms that can cause skin infections, but the most common cause is fungi. Fungi are a type of microorganism that can live on the skin and cause various infections. Here are some key points to consider:
1. Fungi thrive in warm and moist environments, making the skin an ideal breeding ground for them.
2. Fungal skin infections can affect different parts of the body, including the feet (athlete's foot), groin (jock itch), and scalp (ringworm).
3. These infections are usually characterized by symptoms such as redness, itching, and the formation of a rash or blisters.
4. Fungal skin infections can be spread through direct contact with an infected person or by touching contaminated surfaces, such as towels or clothing.
5. Treatment for fungal skin infections often involves the use of antifungal medications, such as creams, lotions, or oral medications, to eliminate the fungi.
6. It's important to practice good hygiene, keep the skin clean and dry, and avoid sharing personal items to prevent the spread of fungal infections.
In conclusion, while there are other microorganisms that can cause skin infections, fungi are the most common culprit. Understanding the causes and symptoms of fungal skin infections can help in prevention and prompt treatment.

Causes of Kala-azar
Kala-azar, also known as visceral leishmaniasis, is caused by the parasite Leishmania. Here is a detailed explanation of why Leishmania is the correct answer:
Leishmania:
- Leishmania is a genus of parasites that are transmitted to humans through the bites of infected sandflies.
- There are several species of Leishmania that can cause kala-azar, including Leishmania donovani and Leishmania infantum.
- The parasites multiply within the human body, primarily affecting the liver, spleen, and bone marrow.
Other options:
- Ascaris: Ascaris is a parasitic roundworm that primarily infects the intestines. It is not responsible for causing kala-azar.
- Trypanosoma: Trypanosoma is a genus of parasites that causes diseases such as African sleeping sickness and Chagas disease. It does not cause kala-azar.
- Bacteria: Although bacterial infections can cause various diseases, kala-azar is specifically caused by the Leishmania parasite and not by bacteria.
In conclusion, the correct answer for the cause of kala-azar is Leishmania.

Process of the Active Immune System Employing Many Cells to the Affected Tissue
The process in which the active immune system employs many cells to the affected tissue is called inflammation. Here's a detailed explanation:
Definition of Inflammation:
Inflammation is a complex biological response to harmful stimuli, such as pathogens, damaged cells, or irritants. It is a protective response by the immune system to remove the cause of injury, initiate tissue repair, and restore normal function.
Steps Involved in the Inflammatory Process:
1. Recognition: The immune system recognizes the presence of harmful stimuli through pattern recognition receptors (PRRs) on immune cells.
2. Activation: Upon recognition, immune cells release chemical signals called cytokines and chemokines, which activate other immune cells and attract them to the affected tissue.
3. Increased Blood Flow: Cytokines cause blood vessels in the area to dilate, leading to increased blood flow. This results in redness and warmth at the site of inflammation.
4. Increased Vascular Permeability: Cytokines also increase the permeability of blood vessels, allowing immune cells and fluid to enter the affected tissue. This leads to swelling or edema.
5. Recruitment of Immune Cells: Immune cells, such as neutrophils and macrophages, are recruited to the inflamed tissue to eliminate the harmful stimuli. They phagocytose (engulf) pathogens or damaged cells and release antimicrobial substances.
6. Tissue Repair: Inflammation also initiates the process of tissue repair. Fibroblasts produce collagen, which helps in the formation of new tissue and wound healing.
Functions of Inflammation:
- Elimination of pathogens and damaged cells
- Initiation of tissue repair and regeneration
- Recruitment of immune cells to the affected tissue
- Activation of immune responses
In conclusion, the process in which the active immune system employs many cells to the affected tissue is called inflammation. It is a crucial defense mechanism that plays a vital role in maintaining the body's overall health and well-being.

Definition of Vectors:

• A: Animals carry the infecting agents from sick person to another healthy person


• B: Microorganisms which cause many diseases


• C: Infected person


• D: Diseased plants

Detailed

Vectors can be defined as:

• Animals carry the infecting agents from sick person to another healthy person: Vectors are organisms, typically animals or insects, that can transmit infectious pathogens (such as bacteria or viruses) from one host to another. They act as carriers and can spread diseases from a sick person to a healthy person.


• Microorganisms which cause many diseases: While microorganisms can cause diseases, they are not specifically defined as vectors. Vectors are the carriers of the microorganisms, rather than the microorganisms themselves.


• Infected person: An infected person is not considered a vector unless they are actively transmitting the infectious pathogen to another person. The term "vector" typically refers to the carrier organism rather than the infected person.


• Diseased plants: Plants can be affected by various diseases, but they are not considered vectors. Vectors are primarily associated with animals or insects that transmit pathogens.

Therefore, the correct answer is option A: Animals carry the infecting agents from sick person to another healthy person.

Antibiotics used in the treatment of bacterial and fungal diseases are not the names of useful bacteria, toxins produced by bacteria, or drugs manufactured to kill viruses. The correct answer is D: products of metabolism in some bacteria.
Here is a detailed explanation:
1. Antibiotics:
- Antibiotics are medications that are used to treat bacterial and fungal infections.
- They work by either killing the bacteria/fungi or inhibiting their growth.
2. Bacterial and fungal diseases:
- Bacterial diseases are caused by harmful bacteria that invade the body and cause an infection. Examples include strep throat, urinary tract infections, and pneumonia.
- Fungal diseases are caused by fungi, such as Candida or Aspergillus. Examples include athlete's foot, ringworm, and yeast infections.
3. Products of metabolism in some bacteria:
- Antibiotics are often derived from the metabolic processes of certain bacteria.
- These bacteria produce natural chemicals that have antimicrobial properties to protect themselves from other bacteria or fungi.
- Scientists have identified and isolated these antibiotic compounds, and they are used as medications to treat bacterial and fungal infections.
4. Examples of antibiotics:
- Penicillin: Derived from the Penicillium fungus, it is effective against a wide range of bacterial infections.
- Streptomycin: Produced by the bacterium Streptomyces griseus, it is used to treat tuberculosis and other bacterial infections.
- Amphotericin B: Derived from the bacterium Streptomyces nodosus, it is used to treat severe fungal infections.
In conclusion, antibiotics used in the treatment of bacterial and fungal diseases are products of metabolism in some bacteria. They are not the names of useful bacteria, toxins produced by bacteria, or drugs manufactured to kill viruses.

Jaundice is a disease of the liver.

Jaundice is a condition characterized by the yellowing of the skin, eyes, and mucous membranes due to an accumulation of bilirubin in the body. Bilirubin is a yellow pigment produced during the breakdown of red blood cells. It is normally processed by the liver and excreted in the bile.

When the liver is not functioning properly, bilirubin cannot be processed and eliminated effectively, leading to its buildup in the body. This results in the characteristic yellowing of the skin and eyes seen in jaundice.

Causes of Jaundice:
- Hepatitis: Inflammation of the liver caused by viral infection (hepatitis A, B, C, etc.).
- Alcoholic liver disease: Excessive alcohol consumption can damage the liver and impair its ability to process bilirubin.
- Liver cirrhosis: Chronic liver disease characterized by scarring of the liver tissue, leading to impaired liver function.
- Gallstones: Obstruction of the bile ducts by gallstones can prevent the flow of bile and cause jaundice.
- Hemolytic anemia: Increased breakdown of red blood cells can overload the liver with bilirubin.
- Medications: Certain medications, such as acetaminophen and some antibiotics, can cause liver damage and jaundice.
- Liver cancer: Tumors in the liver can disrupt its normal functioning and cause jaundice.
Symptoms of Jaundice:
- Yellowing of the skin, eyes, and mucous membranes
- Dark urine
- Pale stools
- Fatigue
- Abdominal pain
- Nausea and vomiting
- Loss of appetite
Treatment of Jaundice:
- The treatment of jaundice depends on the underlying cause.
- In some cases, supportive care, such as rest, adequate hydration, and a nutritious diet, may be sufficient.
- Medications may be prescribed to treat the underlying condition, such as antiviral drugs for hepatitis or medications to dissolve gallstones.
- In severe cases, hospitalization may be necessary for close monitoring and specialized treatment.
It is important to consult a healthcare professional for an accurate diagnosis and appropriate management of jaundice.

Providing living conditions that are not crowded can help prevent:

• Air-borne diseases: When living conditions are overcrowded, there is a higher chance of air-borne diseases spreading. Crowded spaces increase the risk of respiratory infections being transmitted from person to person through coughing, sneezing, or close contact.



• Water-borne diseases: Overcrowded living conditions can lead to inadequate sanitation and poor hygiene practices, which can contribute to the spread of water-borne diseases. Contaminated water sources and improper disposal of waste can contaminate the water supply, leading to diseases like cholera, dysentery, and typhoid.



• Vector-borne diseases: Crowded living conditions provide favorable environments for vectors such as mosquitoes, flies, and ticks to thrive. These vectors can transmit diseases like malaria, dengue fever, Zika virus, and Lyme disease. By reducing overcrowding, the breeding and transmission of these diseases can be minimized.



• Sexually transmitted diseases: While living conditions may not directly impact the transmission of sexually transmitted diseases (STDs), overcrowding can contribute to risky sexual behaviors and a lack of privacy, which can increase the likelihood of STD transmission.

Therefore, by providing living conditions that are not crowded, we can reduce the risk of air-borne, water-borne, and vector-borne diseases, as well as promote better sexual health practices.

DPT vaccine is given to develop immunity against the following diseases:
- Tetanus: DPT vaccine provides protection against tetanus, which is caused by the bacterium Clostridium tetani. Tetanus is a serious infection that affects the nervous system and can lead to muscle stiffness and spasms.
- Diphtheria: DPT vaccine also provides immunity against diphtheria, which is caused by the bacterium Corynebacterium diphtheriae. Diphtheria primarily affects the throat and can lead to difficulty breathing, heart problems, and even death.
- Pertussis: The DPT vaccine also protects against pertussis, commonly known as whooping cough. Pertussis is a highly contagious respiratory infection caused by the bacterium Bordetella pertussis. It can cause severe coughing spells and can be particularly dangerous for infants and young children.
- All of these: The DPT vaccine provides immunity against all three of these diseases - tetanus, diphtheria, and pertussis. It is a combination vaccine that contains antigens from each of these bacteria to stimulate the immune system and develop protective immunity.
By receiving the DPT vaccine, individuals can significantly reduce their risk of contracting and spreading these serious infectious diseases. It is typically administered in a series of doses during childhood and may require booster shots in adolescence or adulthood to maintain immunity.

The Severity of Disease Manifestation Depends On:

1. The number of microbes causing the disease: The higher the number of microbes present in the body, the more severe the disease manifestation is likely to be. This is because a larger microbial load can overwhelm the body's immune system and lead to more severe symptoms.


2. The nutrition we have: Adequate nutrition is essential for a strong immune system, which plays a crucial role in fighting off infections. Poor nutrition can weaken the immune system, making individuals more susceptible to severe disease manifestation.


3. The organ infected/affected: The severity of the disease can vary depending on the organ or organs affected by the infection. Some organs may be more vital or sensitive, leading to more severe symptoms and complications.


4. The strength of the infectious agent: Different infectious agents have varying levels of virulence, which refers to their ability to cause severe disease. Some infectious agents may be more aggressive and potent, resulting in a higher likelihood of severe disease manifestation.

In conclusion, the severity of disease manifestation is influenced by factors such as the number of microbes causing the disease, the individual's nutrition status, the organ affected, and the strength of the infectious agent. Understanding these factors can help in determining the appropriate treatment and management strategies for individuals affected by the disease.

Correct Answer is C.

Because penicillin is a drug which won't let the survival of bacteria. Its an antibiotic. Hence, will kill them and won't let them do their work or in other words, will interrupt in their pathway.