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Thermoregulation involves maintaining an internal body temperature within a tolerable range. Which of the following organisms are considered ectothermic?
Question 1 Explanation:
The correct answer is (C). Snakes gain most of their heat from an outside source, making them ectotherms.
Which types of animals excrete nitrogenous waste in the form of ammonia?
Question 2 Explanation:
The correct answer is (A). Animals that excrete ammonia need access to lots of water because ammonia can only be tolerated at very low concentrations.
Which description best describes a cell-mediated response to a pathogen?
Defenses, such as skin, mucous membranes and secretions that form a barrier
The proliferation of B cells
Antibodies defending against infections in body fluids
Cytotoxic T cells defending the body against cells
Question 3 Explanation:
The correct answer is (D). Cytotoxic T cells attack foreign cells, cells infected with a virus and cancerous cells.
Saliva, tears, epithelial tissues and the mucous membranes of the digestive, respiratory, urinary and reproductive tracts make up which part of the mammalian immune system?
Question 4 Explanation:
The correct answer is (A). Barrier defenses block the entry of pathogens into the body.
If a body cell does not have the protein called a class I MHC molecule on its surface, it is likely that it has been infected by a virus or converted into a cancerous state. What type of cell patrols the body, attaches to cells without class I MHC molecules, and kills the cell so it cannot spread the virus or cancer?
Natural killer cells
Question 5 Explanation:
The correct answer is (B). Natural killer cells help recognize and eliminate certain diseased cells in vertebrates by secreting chemicals if they do not have a protein called a class I MHC molecule on their surface (with the exception of red blood cells).
Which type of response to a pathogen in plants leads to cell and tissue death near the infection site, thereby preventing the spread of the disease?
Systemic acquired resistance
Recruitment of parasitoids
Question 6 Explanation:
The correct answer is (C). A hypersensitive response takes place when a plant produces antimicrobial molecules, seals off infected cells, and kills off cells and/or tissues that are infected. System acquired resistance involve signaling molecules that put the entire plant on alert for a pathogen. Gene-for-gene recognition is the mechanism that allows the plant to recognize pathogens based on the recognition of pathogen-derived molecules. Plants recruit parasitic organisms that defend the plant against herbivores (not pathogens).
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