4.1.3 Animal defences against pathogens

• What are viruses?

  Microscopic infectious agents
• What type of organisms are fungi?

  Eukaryotic organisms
• Prions are infectious agents composed of abnormally folded proteins
• Steps of the inflammatory response

  1️⃣ Increased blood flow to injury site

  2️⃣ Recruitment of immune cells

  3️⃣ Tissue repair
• Chemical barriers like gastric acid break down pathogens using acids, enzymes, and lysozymes
• What are the specialized cells of the adaptive immune system?

  B cells and T cells
• The adaptive immune system relies on specialized lymphocytes called B cells and T cells
• Memory cells generated by the adaptive immune system provide long-term protection against pathogens
• Cellular immunity relies on T cells to directly attack infected cells
• Humoral immunity is effective against intracellular pathogens like viruses.

  False
• Match the pathogen type with its description:

  Viruses ↔️ Microscopic infectious agents that replicate inside living cells

  Bacteria ↔️ Single-celled microorganisms that cause various diseases

  Fungi ↔️ Eukaryotic organisms including yeasts and molds
• The innate immune system provides immediate and non-specific protection against pathogens.


  True
• Natural killer cells target and eliminate infected or cancerous cells
• The adaptive immune system relies on specialized lymphocytes called B cells and T cells
• The ability to generate memory cells allows the adaptive immune system to mount a more rapid and effective response to pathogens
• Plasma cells secrete antibodies into the bloodstream as part of humoral immunity.

  True
• Humoral immunity depends on B cells producing antibodies
• Which type of pathogens is cellular immunity most effective against?

  Intracellular pathogens
• Order the steps of the adaptive immune response:

  1️⃣ Pathogen recognition

  2️⃣ Activation of immune cells

  3️⃣ Cellular or humoral response

  4️⃣ Pathogen neutralization

  5️⃣ Formation of memory cells
• What proteins produced by B cells recognize and neutralize pathogens?

  Antibodies
• IgG antibodies are the first to be produced during an infection.

  False
• The main phagocytic cells in the innate immune system are macrophages and neutrophils
• A phagosome is formed when a phagocyte engulfs a pathogen.


  True
• What is the purpose of the inflammatory response?

  Protective reaction to injury
• Match the sign of inflammation with its explanation:

  Redness ↔️ Increased blood flow

  Heat ↔️ Elevated temperature due to blood flow

  Swelling ↔️ Fluid accumulation in tissues

  Pain ↔️ Stimulation of sensory nerves
• What are the main types of pathogens that can cause disease in animals?

  Viruses, bacteria, fungi, protists, prions
• Match the pathogen type with its description:

  Viruses ↔️ Microscopic agents that replicate inside cells

  Bacteria ↔️ Single-celled microorganisms

  Fungi ↔️ Eukaryotic organisms including yeasts

  Protists ↔️ Diverse eukaryotic microorganisms

  Prions ↔️ Infectious proteins causing misfolding
• Bacteria are single-celled microorganisms that can live in a wide range of environments
• Bacteria are single-celled microorganisms that can live in a wide range of environments
• Protists are always pathogens that cause disease.

  False
• What is the purpose of the innate immune system?

  Immediate and non-specific protection
• Natural killer (NK) cells target and eliminate infected or cancerous cells.

  True
• Match the innate immune mechanism with its description:

  Physical Barriers ↔️ Prevent pathogen entry

  Chemical Barriers ↔️ Break down pathogens

  Phagocytosis ↔️ Engulf and destroy pathogens

  Inflammation ↔️ Promote immune cell recruitment

  Natural Killer (NK) Cells ↔️ Target infected or cancerous cells
• When a pathogen is detected, the adaptive immune system undergoes clonal selection
• Clonal selection occurs when lymphocytes bind to antigens and proliferate into effector and memory cells.


  True
• Match the type of immunity with its primary component:

  Cellular immunity ↔️ T cells

  Humoral immunity ↔️ B cells
• Humoral immunity depends on plasma cells secreting antibodies
• Cellular immunity provides direct cell-to-cell defense, while humoral immunity uses circulating antibodies
• Prions are infectious agents composed of abnormally folded proteins
• Match the innate immune mechanism with its example:

  Physical barriers ↔️ Skin

  Chemical barriers ↔️ Gastric acid

  Phagocytosis ↔️ Macrophages

  Inflammation ↔️ Swelling at an injury