Hybrid seeds are deliberately crossbred for particular traits, such as growth pattern or disease resistance. they have been hand-pollinated and are patented, often sterile, and genetically identical within food types. these plants are usually grown in a monocultural environment and are cultivated for mass production and sale. they must be sturdy to withstand mechanical picking and cross-country shipping. they do not compare to the quality and taste of heirloom plants, but they do produce large, healthy fruit that appeals to most shoppers. unlike heirloom seeds, if one saves a hybrid seed, one

1. an enzyme is considered a(n) because it speeds up a chemical reaction without being used up.2. in a catalyzed reaction, a reactant is often called a(n) . an enzyme is specific because the shape of its matches only particular reactants.4. an enzyme speeds up reactions by lowering the . the between an active site and its substrate often strains bonds and the reaction proceed.6. a( , which is often a vitamin, binds to an enzyme and plays a role in catalysis.7. high temperatures or changes in ph can an enzyme, causing it to lose its shape and biological activity.

Penicillin is hydrolyzed and thereby rendered inactive by penicillinase (also known as β-lactamase), an enzyme present in some resistant bacteria. the mass of this enzyme in staphylococcus aureus is 29.6 kd. the amount of penicillin hydrolyzed in 1 minute in a 10-ml solution containing 10-9 g of purified penicillinase was measured as a function of the concentration of penicillin. assume that the concentration of penicillin does not change appreciably during the assay. penicillin(μm) amount hydrolyzed(nmol) 1 0.11 3 0.25 5 0.34 10 0.45 30 0.58 50 0.61 (a) plot v0 versus [s] and 1/v0 versus 1/[s] for these data. does penicillinase appear to obey michaelis-menten kinetics? if so, what is the value of km? (b) what is the value of vmax? (c) what is the turnover number of penicillinase under these experimental conditions? assume one active site per enzyme molecule.

Aspecies has evolved an asexual mode of reproduction by having offspring develop from unfertilized eggs. which of the following will be true of this species' response to natural selection? there will be more deaths from natural selection because there is no mutation. there will be less genetic variation from recombination and a risk of not adapting quickly to environmental change. the species will increase in numbers because genetic variation is increased. the species will compensate for loss of genetic variation by hybridizing with other species. there will be fewer deaths from natural selection because sexual recombination always leads to extinction.