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Questions and Answers
What is the name of the bacteria that causes tuberculosis?
What is the name of the bacteria that causes tuberculosis?
Mycobacterium tuberculosis
What are the two main types of immune responses?
What are the two main types of immune responses?
What type of cell is responsible for engulfing and digesting dead cells and invasive microorganisms?
What type of cell is responsible for engulfing and digesting dead cells and invasive microorganisms?
Phagocytes
What is the name of the process where pathogens are engulfed and destroyed by phagocytes?
What is the name of the process where pathogens are engulfed and destroyed by phagocytes?
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Match the following types of lymphocytes with their primary roles:
Match the following types of lymphocytes with their primary roles:
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What cells are responsible for producing antibodies?
What cells are responsible for producing antibodies?
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The primary immune response is faster and stronger than the secondary immune response.
The primary immune response is faster and stronger than the secondary immune response.
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What allows the body to mount a faster and more robust immune response to a pathogen it has encountered before?
What allows the body to mount a faster and more robust immune response to a pathogen it has encountered before?
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Which of the following methods of acquiring immunity involves the body producing its own antibodies?
Which of the following methods of acquiring immunity involves the body producing its own antibodies?
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Which of the following is an example of passive immunity?
Which of the following is an example of passive immunity?
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What is the name given to the constant battle between hosts and pathogens as both evolve and develop new ways to outwit each other?
What is the name given to the constant battle between hosts and pathogens as both evolve and develop new ways to outwit each other?
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Study Notes
Edexcel International A Level Biology - Immunity
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Immunity: A disease is an illness or disorder of the body or mind that leads to poor health. Infectious diseases are caused by pathogens that can spread between individuals. Examples include: bacteria (like Mycobacterium tuberculosis causing TB), some fungi and all viruses. Not all viruses are pathogenic to humans.
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Tuberculosis (TB): TB is caused by the bacterium Mycobacterium tuberculosis. Transmission occurs through tiny droplets released from the lungs when infected people cough or sneeze. The bacteria are engulfed by phagocytes, but can survive and reproduce within them. In individuals with a healthy immune system, bacteria can remain dormant. However, if not treated the bacteria can cause significant damage to the lungs, leading to respiratory failure and possibly death. TB symptoms can appear in weeks to years after infection.
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HIV (Human Immunodeficiency Virus): HIV is a retrovirus with RNA genetic material. Transmission can occur through sexual intercourse, blood donation, sharing needles, from mother to child (across the placenta, during birth or through breast milk). HIV infects helper T cells, crucial for activating B cells (antibody-producing cells). Once infected, HIV replicates within the helper T cells, destroying them. Early stages might be asymptomatic. Later stages present with more severe symptoms due to weaker immune defenses. Progression to AIDS (Acquired Immune Deficiency Syndrome) signifies advanced HIV infection, characterized by severe opportunistic infections.
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HIV Replication: The virus enters helper T cells, releases RNA, and uses reverse transcriptase to convert RNA to DNA. Integrated viral DNA uses host cell machinery for viral component replication and assembly, new viruses budding from the host cell to infect other cells.
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Symptoms of AIDS: Initially, flu-like symptoms appear. The immune system weakens, leading to opportunistic infections (like TB). Ultimately, AIDS sufferers die from these infections.
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Pathogen Entry Routes:
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Inhalation: Droplets suspended in the air during coughs, sneezes, or talking.
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Ingestion: Contaminated food or drinks.
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Indirect Contact: Contact with contaminated objects (bedding, towels, surfaces).
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Direct Contact: Direct contact with skin or body fluids.
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Inoculation: Entry through breaks in the skin (e.g., bites, scratches).
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Vectors: Living organisms (like insects) that carry pathogens and transmit them.
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Barriers to Pathogen Entry:
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Skin: Physical barrier, blood clotting mechanisms.
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Stomach Acid: Acidic environment harmful to many pathogens.
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Microorganisms of the Gut/Skin: Microorganisms compete for resources.
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Lysozyme: An enzyme in secretions (tears, saliva) that damages bacterial cell walls.
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Non-Specific Immune Response: A general response regardless of the pathogen (e.g., inflammation, phagocytosis, interferons).
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Inflammation: Swelling, redness, and pain triggered by histamine.
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Phagocytosis: Cells (phagocytes) engulf and destroy pathogens.
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Interferons: Proteins that prevent viruses from replicating.
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Specific Immune Responses: A targeted response to a particular pathogen.
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Antigens: Molecules that trigger an immune response. They are found on cells and viruses and are recognized as either "self" or "non-self" by the immune system.
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Lymphocytes: Two main types - T cells and B cells each with diverse, unique cell receptors critical for recognizing specific pathogens.
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Lymphocytes (Types & Roles):
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T Cells: Mature in the thymus, have specific T cell receptors. Activated when encountering antigens on cells. Several types including helper, killer, and memory cells.
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B Cells: Mature in bone marrow, have antibody receptors (antibodies). Activated when an antigen binds to their receptor. Some produce antibodies, others become memory cells (for a faster, stronger response to future encounters with the specific antigen).
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Developing Immunity:
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Primary Response: Immune system's first encounter with a pathogen. A slower response, with low antibody concentrations due to the need to clone appropriate lymphocytes.
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Secondary Response: Subsequent encounters with the same pathogen. A faster and stronger response due to the presence of memory cells. Higher antibody concentrations, potentially eliminating the pathogen before symptoms appear.
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Active Immunity: Acquired through direct exposure to a pathogen (natural) or via vaccination (artificial). Body produces memory cells for long term protection.
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Passive Immunity: Acquired without an immune response, (e.g. antibodies from mother or vaccination) is temporary, providing antibodies from another source.
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Pathogens vs Hosts (Evolutionary Race): Evolutionary arms race between pathogens adapting to evade host immune systems and hosts evolving ways to combat these pathogens. Pathogens have developed mechanisms like antigenic variations to evade detection and destruction by the immune system. Examples include HIV and Mycobacterium tuberculosis.
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Description
This quiz focuses on the concepts of immunity, including the diseases caused by pathogens, specifically tuberculosis and HIV. Understand how these infections operate within the immune system and the effects they can have on human health. Test your knowledge on the mechanisms of transmission and the immune response to these diseases.
