21.  Microorganisms that live in severe habitats, such as very hot, acidic or salty environments, are called  
A.  Thermophiles
B.  Halophiles
C.  Psychrophiles
D.  Extremophiles
E.  Barophiles

22.  Organisms called _____ live on or in the body of a host and cause some degree of harm.  
A.  Mesophiles
B.  Thermophiles
C.  Commensals
D.  Pathogens
E.  Halophiles

23.  The term obligate refers to  
A.  The ability to exist in a wide range of conditions
B.  Existing in a very narrow niche
C.  Using chemicals for energy production
D.  Using light for energy production
E.  Using oxygen for metabolism

24.  The term facultative refers to  
A.  The ability to exist in a wide range of conditions
B.  Existing in a very narrow niche
C.  Using chemicals for energy production
D.  Using light for energy production
E.  Using oxygen for metabolism

25.  The movement of molecules from an area of high concentration to an area of lower concentration is called  
A.  Facilitated diffusion
B.  Diffusion
C.  Active transport
D.  Osmosis
E.  Endocytosis

26.  Diffusion of water through a semi permeable membrane is called  
A.  Facilitated diffusion
B.  Diffusion
C.  Active transport
D.  Osmosis
E.  Endocytosis

27.  The movement of substances from lower to higher concentration across a semi permeable membrane that must have a specific protein carrier and cell expenditure of energy is called  
A.  Facilitated diffusion
B.  Diffusion
C.  Active transport
D.  Osmosis
E.  Endocytosis

28.  The movement of substances from higher to lower concentration across a semi permeable membrane that must have a specific protein carrier but no energy expenditure is called  
A.  Facilitated diffusion
B.  Diffusion
C.  Active transport
D.  Osmosis
E.  Endocytosis

29.  The use of energy by a cell to enclose a substance in its membrane by forming a vacuole and engulfing it is called  
A.  Facilitated diffusion
B.  Diffusion
C.  Active transport
D.  Osmosis
E.  Endocytosis

30.  Bacteria living in a freshwater stream that are moved to salty seawater would  
A.  Be in a hypotonic solution
B.  Gain water
C.  Be in a isotonic solution
D.  Shrivel
E.  None of the choices are correct