Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Pathogens are organisms or viruses that cause disease. They include bacteria, viruses, fungi, and protozoa.
The primary defense against pathogens consists of the skin and mucous membranes. The skin has a low and secretes sebum to inhibit bacterial growth, while mucous membranes secrete lysozyme and trap pathogens in mucus.
Blood clotting is a cascade of reactions. When a vessel is damaged, platelets release clotting factors that convert the plasma protein prothrombin into the active enzyme thrombin.
Thrombin catalyzes the conversion of the soluble plasma protein fibrinogen into the insoluble fibrous protein fibrin, which forms a mesh that traps blood cells and platelets.
Phagocytic white blood cells (macrophages) provide non-specific immunity by ingesting pathogens through endocytosis and digesting them using lysosomes.
Specific immunity involves production of antibodies by -lymphocytes in response to specific antigens. Each antibody is specific to a particular antigen.
Antibiotics block metabolic pathways in prokaryotic cells (e.g., cell wall synthesis, ribosome protein synthesis) but are ineffective against viruses because viruses lack their own metabolism and use host cell machinery.
The Human Immunodeficiency Virus () specifically targets and destroys -helper cells ( cells), leading to a reduction in antibody production and the eventual onset of .
Antibiotic resistance in bacteria (e.g., ) is an example of natural selection, where mutations and the exchange of plasmids allow survival in the presence of the drug.
📐Formulae
💡Examples
Problem 1:
Describe the role of platelets and the specific chemical conversion they trigger to prevent blood loss.
Solution:
Platelets aggregate at the site of a wound and release clotting factors. These factors initiate the conversion of to . then converts into .
Explanation:
The conversion involves changing a soluble protein into an insoluble mesh-like structure to stabilize the clot.
Problem 2:
Why can antibiotics be used to treat a bacterial infection caused by a ribosome-bearing organism, but not a viral infection?
Solution:
Antibiotics target prokaryotic-specific processes such as the synthesis of the peptidoglycan cell wall or ribosome function. Viruses are non-living entities that replicate using the host's eukaryotic ribosomes and metabolic pathways, which are not affected by antibiotics.
Explanation:
Selective toxicity allows antibiotics to kill bacteria without harming the human host, but since viruses lack independent metabolism, there is no target for the drug within the virus itself.
Problem 3:
Explain the effect of on the immune system's ability to produce antibodies.
Solution:
infects and destroys -helper cells. Since -helper cells are required to activate -lymphocytes (which differentiate into antibody-secreting plasma cells), their destruction leads to a failure in the production of specific antibodies.
Explanation:
Without cells, the communication between the innate and adaptive immune systems is severed, leaving the body vulnerable to opportunistic infections.