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Biology 251 Exam 1 Questions and Solutions
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Biology 251 Exam 1 Questions and Solutions
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Biology 251 Exam 1symbiotic relationship - Answer-two organisms live together in a close partnership. at least one person
in the relationship benefits
mutualism - Answer-obligatory, dependent, both members benefit
commensalism - Answer-commensal member benefits, the host is not harmed but does not benefit
parasitism - Answer-parasite is dependent and benefits, hosts is harmed
3 types of symbiotic relationships - Answer-mutualism, commensalism, parasitism
non-symbiotic relationship - Answer-organisms are free living, relationships *not* required for survival
syntropy - Answer-communal feeding between organisms in a shared habitat
antagonism/amenalism - Answer-actions of one organism affect the success of survival of others in the
same community (AKA competition)
,2 examples of non-symbiotic relationships - Answer-syntropy, antagonism/amenalism
action of amenalism - Answer-can produce toxic substances that inhibit the growth of other bacteria
how do biofilms communicate? - Answer-quorum sensing
biofilms - Answer-result when organisms attach to a substrate by some forming an extracellular matrix
that binds them together in complex organized layers
what dominates the structure of most natural environments on earth? - Answer-biofilms
where are biofilms found? - Answer-both artificial and natural surfaces
biofilm formation steps - Answer-reversible attachment, irreversible attachment (quorum sensing),
microcolony, mature biofilm, dispersal.
function of matrix - Answer-allows cells to adhere to each other and to the surface
what happen when a cell loses its flagella? why is this important in biofilm formation? - Answer-lose
motility and then the biofilm forms. the cells do not need to be mobile, they are going to stay put in the
biofilm, so flagella are not needed
microcolony - Answer-biofilm beginning to grow in size. first maturation stage
mature biofilm - Answer-complex biofilm structure, cells diversify, cell growing, continues to mature
, dispersal - Answer-black and white cells, some with flagella, biofilm can now open up, free living cells
can now leave and form new micro-colonies to make more biolfims
reversible attachment - Answer-cells attach and detach from the surface
irreversible attachment - Answer-cells multiply and start producing biofilm matrix components
normal microbiota - Answer-symbiotic microbes normally present in and on the human body, ex
bacteria, fungi, few protozoa
why are antibiotics becoming less beneficial? - Answer-microbes able to pick up DNA and antibiotic
resistance and pass this along to other microbes
when should you take antibiotics? - Answer-only when absolutely necessary
what 2 things do microbes need for nutrients? - Answer-carbon and energy
difference between heterotroph and autotrophs - Answer-where they get their carbon
heterotroph - Answer-obtain carbon in an organic form made by other living organisms such as
macromolecules
autotroph - Answer-organisms that uses inorganic molecules (CO2) as its carbon source, not
nutritionally dependent on other living things
2 classification groups based on how an organism obtains its energy source - Answer-chemotroph and
phototrophs
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