Briefly explain how the body's first line of defense against pathogens works
What will be an ideal response?
The first line of defense includes physical and chemical barriers. The skin, a major physical barrier, acts as an impermeable shield against invasion of the pathogens into the body. Skin forms a watertight barrier that is resistant to toxins and enzymes produced by most pathogens. Skin cells are continuously shed and replaced. Chemical protectors associated with the skin include oils and sweat that are slightly acidic, which prevents microbial growth and washes bacteria away. The mucous membranes that cover many surfaces in the body, including the respiratory, digestive, urinary, and reproductive systems, are also physical barriers. Other chemical barriers include acidic conditions of the stomach lining and vagina and lysozyme in tears and saliva.
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Four of the five answers listed below are types
of intercellular connections. Select the exception. a. tight junctions b. gap junctions c. plasmodesmata d. adhering junctions e. plasmalemma
During inhalation, the diaphragm
A) relaxes and flattens. B) contracts and flattens. C) relaxes and becomes dome-shaped. D) contracts and becomes dome-shaped.
Biologists have found evidence that eukaryotic cells evolved from prokaryotic organisms by a process of intracellular ________.
Fill in the blank(s) with the appropriate word(s).
Large solutes are transported across a cell membrane by ________ .
a. osmosis b. passive transport c. vesicles d. diffusion e. proteins