Awater sample could be negative for enterococcus and coliforms and still be a major public health threat. why?
why can filitration be used to sterilize culture media? why can filtration be used in sanitation?
what basic assumption is made in the membrance filter technique if the number of bacteria is determined from the number of colonies?
what difference exsits between e. coli and e. aerogenes regarding their imvic reactions?
is it really necessary to perform a gram stain on the microbes isolated from macconkey or eosin-methylene blue agar used in the presumptive identification of coliforms? why or why not?

answer-

the statement that f(x) = |x+a| + b has exactly one x-intercept is sometimes correct.

solution-

it solely depends on b, whether the function will have one or two or zero x intercept.

this plot of the given function, f(x) = |x+a| + b will be the basic absolute value graph i.e v shape, with vertex translated to (-a, b), instead of origin.

1-   if b is zero, the graph will have exactly one x-intercept, at x= -a

2- if b is positive, the whole graph will be above the x-axis, hence it will have no x-intercepts.

3- if b is negative, the graph will be below the x-axis, hence it will have two x-intercepts.

∴ the statement is sometimes true.

answer: the correct option is d. enzyme

lactase and carbonic anhydrase are the examples of enzymes.

lactase is an enzyme, which is present in the small intestine of mammals. it in the digestion of the disaccharide, lactose ( milk sugar) by converting it into two monosachharide, which are glucose and galactose.

carbonic anhydrase is present in the red blood cells. this enzyme plays significant role in the transport of co₂. it in the conversion of co₂ and h₂o into carbonic acid, which is then dissociated into bicarbonate ions and hydrogen ions.