3.Explain the following scientific terms.(3 point each,30 points in total) (1)Plasmid:Small extrachromosomal genetic elements in Prokaryotic cells. (2)Eutrophication:the process by which a body of water becomes enriched in dissolved nutrients (as phosphates)that stimulate the growth of aquatic plant life usually resulting in the depletion of dissolved oxygen (3)Enzyme:A protein with catalytic properties due to its power of specific activation (4)Complimentary Base Pairing:Principle of Nitrogenous bases pairing in DNA or RNA:A-T(U) and G-C. (5)Commensalism:a unidirectional relationship betwen populations in which one population benefits and the other one is unaffected. (6)Biofilm:an assemblage of microorganisms and its associated extracellular products at an interface and typically attached to a surface. (7)Operon:a series of structural genes which are under the control of a Regulatory Gene and functions in a coordinated manner by means of an operator,a promoter,and one or more structural genes. (8)Cell Yield Coefficient(Y):the unit amount of cell mass produced per unit amount of substrate consumed (9)Mesophiles:microorganisms which prefer living at temperature of 25 to 45 degrees. (10)Fluorescence in situ Hybridization(FISH):a process which vividly paints chromosomes or portions of chromosomes with fluorescent molecules 3 3 3. Explain the following scientific terms. （3 point each，30 points in total） (1) Plasmid: Small extrachromosomal genetic elements in Prokaryotic cells. (2) Eutrophication: the process by which a body of water becomes enriched in dissolved nutrients (as phosphates) that stimulate the growth of aquatic plant life usually resulting in the depletion of dissolved oxygen. (3) Enzyme: A protein with catalytic properties due to its power of specific activation. (4) Complimentary Base Pairing: Principle of Nitrogenous bases pairing in DNA or RNA: A – T (U) and G – C. (5) Commensalism: a unidirectional relationship betwen populations in which one population benefits and the other one is unaffected. (6) Biofilm: an assemblage of microorganisms and its associated extracellular products at an interface and typically attached to a surface. (7) Operon: a series of structural genes which are under the control of a Regulatory Gene and functions in a coordinated manner by means of an operator, a promoter, and one or more structural genes. (8) Cell Yield Coefficient (Y): the unit amount of cell mass produced per unit amount of substrate consumed. (9) Mesophiles: microorganisms which prefer living at temperature of 25 to 45 degrees. (10) Fluorescence in situ Hybridization (FISH): a process which vividly paints chromosomes or portions of chromosomes with fluorescent molecules