Test: Treatment And Prevention Of Diseases - Class 9 MCQ

The organism that causes acne is Staphylococcus.
Explanation:
- Acne is a common skin condition that occurs when hair follicles become clogged with oil and dead skin cells.
- Staphylococcus is a type of bacteria that is commonly found on the skin and can contribute to the development of acne.
- Staphylococcus bacteria can thrive in the oily environment of the skin and can cause inflammation and infection in the hair follicles, leading to acne.
- Other factors such as hormonal changes, excessive oil production, and a buildup of dead skin cells can also contribute to the development of acne.
- Lactobacillus is a type of bacteria that is commonly found in the gut and is beneficial for digestion. It does not cause acne.
- Trypanosoma is a parasitic organism that causes diseases such as sleeping sickness and Chagas disease. It does not cause acne.
- Plasmodium is a parasitic organism that causes malaria. It does not cause acne.
Therefore, the correct answer is C: Staphylococcus.

Importance of Childhood Immunisation Programmes:
Childhood immunisation programmes play a crucial role in safeguarding the health and well-being of children. Here are the reasons why these programmes are important:
Lifelong Protection:
- Immunisation provides lifelong protection against several infectious diseases, preventing children from falling ill or experiencing severe complications.
- It helps to build immunity against diseases such as measles, polio, diphtheria, tetanus, whooping cough, hepatitis, and more.
Preventing Outbreaks:
- By vaccinating a significant portion of the population, immunisation programmes can help prevent outbreaks and reduce the spread of contagious diseases.
- This protects not only vaccinated individuals but also vulnerable populations who cannot receive vaccines due to medical reasons.
Herd Immunity:
- Childhood immunisation programmes aim to achieve herd immunity, which occurs when a sufficient proportion of the population is vaccinated, making it difficult for diseases to spread.
- This protects those who are unable to receive vaccines, such as infants, pregnant women, and individuals with weakened immune systems.
Reducing Disease Burden:
- Immunisation programmes help in reducing the burden of vaccine-preventable diseases on healthcare systems.
- By preventing illnesses, hospitalizations, and long-term complications, immunisation saves healthcare resources and improves overall health outcomes.
Improving Overall Health:
- Vaccines not only protect against specific diseases but also contribute to overall health and well-being.
- By preventing infections, immunisation helps children stay healthy, attend school regularly, and reach their full potential.
In conclusion, childhood immunisation programmes provide lifelong protection, prevent outbreaks, contribute to herd immunity, reduce disease burden, and improve the overall health of children.

Immune System
- The immune system is responsible for defending the body against disease-causing microbes, such as bacteria, viruses, and fungi.
- It is a complex network of cells, tissues, and organs that work together to identify and destroy harmful pathogens.
- The immune system can be divided into two main components: the innate immune system and the adaptive immune system.
- The innate immune system provides immediate, nonspecific defense mechanisms against a wide range of pathogens.
- It includes physical barriers (e.g., skin), chemical barriers (e.g., stomach acid), and various types of immune cells (e.g., neutrophils, macrophages) that engulf and destroy pathogens.
- The adaptive immune system is a more specific defense mechanism that develops over time.
- It involves the production of antibodies by B cells and the activation of T cells, which can recognize and eliminate specific pathogens.
- The immune system also has the ability to remember previous encounters with pathogens, providing long-term protection against reinfection.
- Vaccines work by stimulating the immune system to produce a response against specific pathogens, leading to immunity.
- Disorders of the immune system can lead to immunodeficiency (weakened immune response) or autoimmune diseases (immune system attacks the body's own tissues).
- Maintaining a healthy immune system is essential for overall health and well-being. This can be achieved through a balanced diet, regular exercise, adequate sleep, and proper hygiene practices.

Answer:
The correct answer is A:

Trypanosoma

Explanation:
Sleeping sickness, also known as African trypanosomiasis, is caused by a protozoan called Trypanosoma. Here is a detailed explanation:
1. Sleeping Sickness:
- Sleeping sickness is a disease caused by infection with the protozoan parasite Trypanosoma brucei.
- It is transmitted to humans through the bite of infected tsetse flies, which are found in sub-Saharan Africa.
2. Protozoan:
- Protozoa are single-celled microscopic organisms that can cause various diseases in humans and animals.
- Trypanosoma is a genus of protozoa that includes several species responsible for causing different diseases in humans, including sleeping sickness.
3. Trypanosoma:
- Trypanosoma is a flagellated protozoan parasite.
- It has a complex life cycle involving both humans and tsetse flies.
- The parasite exists in two forms: a bloodstream form (found in humans) and a procyclic form (found in tsetse flies).
4. Sleeping Sickness Transmission:
- Tsetse flies become infected with Trypanosoma when they feed on the blood of an infected human or animal.
- The infected flies then transmit the parasite to humans through their bite.
- Once inside the human body, the parasite multiplies and spreads through the bloodstream, causing various symptoms.
In conclusion, sleeping sickness is caused by the protozoan parasite Trypanosoma, making option A the correct answer.

Explanation:
The correct answer is A: Since smallpox virus is closely related to cowpox virus. Here's the detailed explanation:
- Cowpox and smallpox are both caused by viruses, and they belong to the same family called Poxviridae.
- It was observed that milkmaids who contracted cowpox, a less severe disease, did not suffer from smallpox later.
- Cowpox and smallpox viruses share some similarities, and getting infected with cowpox can provide immunity against smallpox.
- The immune system of milkmaids who had cowpox produced antibodies that were effective against smallpox as well.
- This cross-immunity phenomenon is possible because the viruses are closely related and the immune response generated against cowpox can also protect against smallpox.
- This discovery laid the foundation for the development of the smallpox vaccine, where a similar virus (vaccinia virus) was used to induce immunity against smallpox.
- The observation made by milkmaids and the subsequent understanding of the relationship between cowpox and smallpox helped in the eradication of smallpox through vaccination campaigns.
So, the correct explanation for milkmaids who had cowpox not suffering from smallpox later is that the smallpox virus is closely related to the cowpox virus, allowing for cross-immunity.

Why making anti-viral drugs is more difficult than making anti-bacterial medicines:
There are several reasons why making anti-viral drugs is more challenging compared to making anti-bacterial medicines. These reasons include:
1. Viruses have very few biochemical mechanisms of their own:
- Viruses are intracellular parasites that rely on host cells to carry out their life cycle.
- They use the host's cellular machinery to replicate and produce more viruses.
- This limited number of biochemical mechanisms makes it challenging to target specific viral processes without affecting the host cells.
2. Viruses are on the borderline of living and non-living:
- Viruses are often described as "obligate intracellular parasites" because they require host cells to replicate.
- Unlike bacteria, viruses lack the cellular machinery necessary for metabolic activities.
- This unique nature of viruses makes it difficult to find targets for drugs that selectively inhibit viral replication without harming the host cells.
3. Viruses have RNA as their genetic material:
- Many viruses have RNA as their genetic material instead of DNA.
- RNA viruses often mutate rapidly, leading to the emergence of new strains and variants.
- This high mutation rate makes it challenging to develop drugs that can effectively target the rapidly changing viral genetic material.
4. Viruses have a protein coat:
- Viruses are composed of a protein coat, known as a capsid, which protects their genetic material.
- This protein coat can act as a barrier, preventing drugs from reaching and inhibiting the viral genetic material.
- Developing drugs that can effectively penetrate this protein coat and inhibit viral replication is a significant challenge.
In conclusion, making anti-viral drugs is more difficult than making anti-bacterial medicines due to the limited biochemical mechanisms of viruses, their unique nature on the border of living and non-living, the presence of RNA as their genetic material, and the protective protein coat that viruses possess. These factors pose challenges in finding specific targets and developing drugs that can effectively inhibit viral replication without harming the host cells.

Explanation:
Vaccination is a process in which a weakened or inactivated form of a disease-causing microorganism is introduced into the body. This stimulates the immune system to produce an immune response, which leads to the development of immunity against the specific disease. The immune system plays a crucial role in protecting the body from harmful pathogens, and vaccination helps to strengthen and activate it.
The correct answer is D: Activated because vaccination activates the immune system by stimulating the production of antibodies and memory cells. This ensures that the body can mount a quick and effective immune response when exposed to the actual disease-causing microorganism in the future.
Here is a detailed explanation of why the other options are incorrect:



- A: Deactivated: Vaccination does not deactivate the immune system. Instead, it activates and strengthens it.



- B: Degenerated: Vaccination does not cause the immune system to degenerate. It actually enhances the immune response.



- C: Generated: While vaccination does generate an immune response, it does not generate the immune system itself. The immune system is already present in the body; vaccination simply stimulates it.



In conclusion, infants are vaccinated to activate and strengthen their immune system, not to deactivate or degenerate it.

The body of an AIDS patient is unable to fight off even minor infections like the common cold due to:
- HIV virus: The HIV virus itself is capable of causing other minor infections, making the body more susceptible to infections.
- Immune system damage: The HIV virus attacks and damages the immune system, specifically targeting CD4+ T cells, which are a crucial part of the immune response. This leads to a weakened immune system, making it difficult for the body to fight off infections.
- Medication restrictions: While medication can help manage HIV and strengthen the immune system, some AIDS patients may not have access to or be able to take medication due to various reasons, which further compromises their ability to fight off infections.
- Overwhelming HIV replication: The body's immune system is constantly engaged in fighting off the attack of the HIV virus, which replicates rapidly. This constant battle diverts resources and energy away from fighting other infections, leaving the body vulnerable to even minor infections.
It is important for AIDS patients to receive appropriate medical care, including antiretroviral therapy, to help manage HIV and improve immune function, thereby reducing the risk of infections.

Organisms which carry infectious agents from a sick person to another potential host are known as Vectors.
Vectors play a crucial role in the transmission of infectious diseases. They can be either living organisms or inanimate objects that facilitate the spread of pathogens. Here is a detailed explanation of vectors as the answer to the given question:
Definition of Vectors:
Vectors are organisms that can transmit infectious agents from one individual to another. They act as carriers of the pathogen, facilitating its spread and transmission. Vectors can be biological (living organisms) or mechanical (inanimate objects).
Types of Vectors:
There are two main types of vectors:
1. Biological Vectors:
- Biological vectors are living organisms that can carry and transmit infectious agents.
- Examples of biological vectors include mosquitoes, ticks, fleas, and flies.
- These vectors can harbor the infectious agent within their body or transmit it through their bite or excreta.
- Biological vectors are essential in the lifecycle of the pathogen, as they provide a means of transportation and replication for the infectious agent.
2. Mechanical Vectors:
- Mechanical vectors are inanimate objects that can carry infectious agents.
- Examples of mechanical vectors include contaminated medical instruments, needles, or surfaces.
- These vectors do not participate in the lifecycle of the pathogen but can passively carry and transmit the infectious agent.
Role of Vectors in Disease Transmission:
Vectors play a critical role in the transmission of various infectious diseases, including malaria, dengue fever, Lyme disease, and Zika virus. They can introduce the pathogen into a new host population by:
1. Acting as a Reservoir:
- Vectors can serve as a reservoir for the infectious agent, providing a suitable environment for its survival and replication.
- The pathogen can multiply within the vector's body, increasing its chances of transmission to a new host.
2. Facilitating Transmission:
- Vectors can transmit the infectious agent through their bite or excreta.
- When a vector bites a sick individual, it acquires the pathogen. Subsequently, when it bites a new host, it transfers the pathogen, causing infection.
3. Geographic and Seasonal Spread:
- Vectors can contribute to the geographic and seasonal spread of infectious diseases.
- Some vectors are adapted to specific regions or climates, limiting the distribution of the associated disease.
In conclusion, vectors are organisms that carry and transmit infectious agents from a sick person to another potential host. They play a crucial role in the spread and transmission of various diseases. Understanding the role of vectors is essential for implementing effective control and prevention measures to minimize the impact of infectious diseases.

Penicillin kills bacteria through binding of the beta lactam ring to DD-transpeptidase, inhibiting its cross - linking activity and preventing new cell wall formation. The cell walls of gram - negative bacteria are surrounded by a lipopolysaccharide (LPS) layer than prevents antibiotic entry into the cell.