Penicillin is hydrolyzed and thereby rendered inactive by penicillinase, 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. a plot of 1/v_0 versus 1/[s] indicated the v_max=6.8 times^- 10 mol minute^-1. assuming one active site per enzyme molecule, the turnover number for penicillinase is

(a) 337 s^-1
(b) 337 min^-1
(c) 600 hour^-1
(d) 33 hour^-1 600 s^-1

The turnover number is the maximum substrate quantitiy converted to product per enzyme and per second. It can be calculate as follows:

with active enzyme concentration.

In this case we have Vmax an data to calculate

Now

it is not like any option.

If we assume that have the non usual units of and it is

So we need divide by the moles of E (in place of [E])

Now

(pass from to dividing by 60)

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.