Which of the following is a characteristic or structure of skin which makes it a part of our first line of defense?

Name the two types of cell produced when B lymphocytes are activated by an antigen?

An insect that transmits a pathogen from one host to another is a:

Which term is used to describe a disease outbreak over several continents or countries?

When phagocytes squeeze out through capillary walls it is termed:

The following set of elementary reaction steps has been proposed for an overall reaction (not shown).  Identify the catalyst.

An instrument that is used to sterilize with heat under pressure is called a(n):

Calculate the Ka for an unknown monoprotic acid when a {M} M solution of the acid has pH #4 as given in the pH Values table at the bottom of this page. Answer format:  Enter in standard notation, not scientific with 2 sig figs.

At 25°C, the equilibrium constant Kc = 0.0012 for the reaction  B(aq) + C(aq)  ↔  2A(aq)     A solution of 0.80 M of B and 0.80 M of C is mixed and allowed to come to equilibrium. A student does the following steps below to calculate the equilibrium concentration of A.  There is one error in this calculation. Identify the step where the student made an error.

Which of the following types of immunity is provided by breast milk?