As an undergraduate research assistant, you are assisting with a radioisotope tracer experiment. you expose a mature leaf on one side of the lower shoot of a sugar beet plant to 14co2 and then track the movement of the 14c atoms by radiography. where are you least likely to detect 14c? a) the treated leafb) the shoot apical meristemc) the rootsd) a mature upper leaf on the opposite side of the plant from the treated leaf

B: the shoot apical meristem

Explanation:

The test run during the research is meant to determine the approximate age of the treated element. During photsynthesis the plant incorporates the raidoactive carbon isotope, 14C. When the plant dies, these atoms start to transform in 14N (nitrogen isotope) due to radioactive decay. So, while the plant is alive it continues to store more and more 14C in time because of photosynthesis. This means that the more 14C atoms found, the older the part of the plant. The question asks where are you least likely to find 14C, so, we have to determine which part of the plant contains the youngest cells in order to find the answer.

Opcion "c" says the roots. Considering that the roots are the first part of the plant to form, then it shouldn't be the youngest part.

Option "d" suggests a mature upper leaf on the opposite side of the plant from the treated leaf. The fact that it mentions the opposite side of the plant doesn't give us any information that we could use. It is useful, though, to know that it is an upper leaf. This means that it grew after the one that's being treated, so it's youger and surely we would find less 14C atoms than on the treated leaf. Then, we already know that option "a" can't be the answer because the treated leaf came from a lower shoot, meaning it's older.

Here we have two options left. We have to compare "d" (mature upper leaf) with "b" (the shoot apical meristem). If we analyse this we could think that the upper leaf is younger than any cell at the shoot, since the shoot grew first, but, option "b" doesn't talk about any shoot cell, it makes reference to the apical meristem which is the one that takes care of growth. The apical meristem can be found at the tip of the plant, constantly regenerating at a high rate. So, this means that we are most likely to find the youngest cells here, therefore, we are least likely to detect 14C after the experiment.  This is why the answer is: B) the shoot apical meristem.

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.

answer: i have one answer

acids are substances that ionize (break off) in an aqueous solution to produce hydrogen (h+) ions

explanation:

hope this and sorry i could only come up with one answer!