2) Biology Revision - Keeping Healthy - Defence Against Infection

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Microorganisms are tiny living organisms that include bacteria and viruses. They are responsible for causing infectious diseases, commonly known as pathogens. These pathogens invade the body and can cause various illnesses. Therefore, microorganisms accurately describe the organisms that cause infectious diseases such as bacteria and viruses.

Viruses can only reproduce inside host cells which can damage the cell. Once inside, the viruses multiply creating thousands of copies of themselves. These eventually fill the host cell which bursts open and the viruses are released into the bloodstream or airways to damage more cells.

White blood cells don't eat the cells, they injest them.

Bacteria can develop resistance to antibiotics, which means that the antibiotics are no longer effective in killing or inhibiting their growth. This resistance can occur when antibiotics are not taken for the full prescribed course, allowing some bacteria to survive and develop resistance. Overprescribing antibiotics can also contribute to the development of resistant strains, as it exposes bacteria to antibiotics unnecessarily and increases the likelihood of resistance developing. Therefore, the correct answer is "resistant."

Bacteria release toxins. Bacteria are microscopic organisms that can produce and release toxic substances known as toxins. These toxins can be harmful to other organisms, including humans, causing various diseases and infections. Bacterial toxins can damage cells, disrupt normal bodily functions, and lead to symptoms such as fever, inflammation, and tissue damage. Understanding the release of toxins by bacteria is crucial in the diagnosis and treatment of bacterial infections.

An antigen is a protein coating on the pathogen that triggers the body's immune system to recognize and attack the pathogen. The immune system identifies antigens as foreign substances and produces antibodies to neutralize and eliminate them. This immune response is essential for protecting the body against infections and diseases caused by pathogens.

White blood cells, also known as leukocytes, play a crucial role in the immune system by ingesting and destroying pathogens. They are able to recognize foreign substances, such as bacteria, viruses, and other harmful microorganisms, and engulf them through a process called phagocytosis. Once inside the white blood cell, the pathogens are broken down and destroyed, helping to eliminate the threat and protect the body from infection and disease.

Bacteria are living cells that have the ability to multiply rapidly. This means that they can reproduce and increase their population at a fast rate. As they multiply, they release toxins that can cause illness in humans. This explains why bacteria can quickly spread and cause infections or diseases.

Viruses are much smaller than bacteria. While bacteria are single-celled organisms that can be seen under a microscope, viruses are much smaller and can only be observed with an electron microscope. Unlike bacteria, viruses are not considered living organisms as they cannot reproduce on their own and require a host cell to replicate. Due to their small size, viruses are often able to penetrate and infect host cells, causing various diseases.

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Viruses contain a fragment of genetic information inside a protective protein shell. This genetic information can be in the form of DNA or RNA, and it carries the instructions for the virus to replicate and infect host cells. The protective protein shell, called a capsid, helps to shield the genetic material from the external environment and prevent it from being degraded. This allows the virus to survive and potentially cause infection when it enters a suitable host organism.

Pathogens are microorganisms such as bacteria, viruses, or fungi that can cause diseases. However, it is important to note that pathogens themselves are not the disease, but rather they are the agents that trigger the disease. Once they enter the body, pathogens can invade and multiply, leading to the development of various diseases. Therefore, the statement that pathogens are not the disease but only cause the disease is true.

Viruses are known to damage our cells. They invade the host cells and use their machinery to replicate themselves, often causing harm to the host organism in the process. Viruses can disrupt normal cellular functions, leading to cell death or dysfunction. This damage can result in various diseases and illnesses in humans and other organisms.

Cleanliness reduces the risk of infection by promoting personal hygiene practices, maintaining a clean environment in hospitals, and sterilizing equipment. Personal hygiene, such as regular handwashing, helps to prevent the spread of bacteria and viruses. Keeping hospitals clean, including regular cleaning and disinfection of surfaces, reduces the presence of pathogens. Sterilizing equipment ensures that it is free from any harmful microorganisms that could cause infections. Overall, maintaining cleanliness is an essential measure in reducing the risk of infection and promoting a safe and healthy environment.

Semmelweis discovered that disease could be reduced by cleanliness in hospitals. He implemented measures such as doctors wearing appropriate protection, washing hands, and sterilizing equipment. Despite his ideas being ignored at the time, Semmelweis's findings were instrumental in the development of modern hospital hygiene practices.

Antibiotics are medications that are specifically designed to kill or inhibit the growth of bacteria. They target the specific mechanisms and structures that are unique to bacteria, such as their cell walls or protein synthesis. However, antibiotics do not have any effect on viruses, as viruses are fundamentally different from bacteria. Viruses are not living organisms and rely on host cells to reproduce. Therefore, antibiotics are not effective in treating viral infections.

Antibodies and antitoxins are not living but are specialist proteins

Bacteria can cause food poisoning and cholera. Food poisoning occurs when bacteria contaminate food, leading to illness when consumed. Cholera is a bacterial infection that causes severe diarrhea and dehydration. Both conditions are caused by specific bacteria and can be transmitted through contaminated food or water.

Viruses can cause a variety of diseases, including AIDS, rubella, chicken pox, and influenza (flu). AIDS is caused by the human immunodeficiency virus (HIV), which attacks the immune system. Rubella is caused by the rubella virus and can lead to rash, fever, and birth defects if contracted during pregnancy. Chicken pox is caused by the varicella-zoster virus and is characterized by itchy blisters on the skin. Influenza, commonly known as the flu, is caused by influenza viruses and can cause respiratory symptoms such as fever, cough, and body aches.

Vaccines can contain harmless fragments of pathogens, toxins produced by pathogens, live pathogens treated to make them harmless, and dead pathogens. Harmless fragments of pathogens are included in vaccines to stimulate the immune system without causing disease. Toxins produced by pathogens can also be used to stimulate an immune response. Live pathogens can be included in vaccines, but they are treated to make them harmless and unable to cause disease. Dead pathogens are also used in some vaccines to stimulate an immune response.