Introduction

[mary.ws.sh7355]

In the introduction, Unit 4, Question 8, what is the answer? Is it D? because that is usually the answer in relatively low concentrations... (BIO-18 to BIO-19 Master series text book)

[mary.ws.sh7355]

Also, whats the answer for Unit 5 Question 9? is it A? that is if the green dotted lines of positive stimulatory feedback are considered direct conversions. (BIO-20 Master Series Biology Text Book)

[goldstanda3269]

In the introduction, Unit 4, Question 5, what is the answer? Is it D? because that is usually the answer in relatively low concentrations...

There is no Unit 4, Question 5, and I am not sure what content you are referring to. Is there something specific about the worked solution that was not clear?

Note that the answers and worked solutions follow each question set in the book.

[mary.ws.sh7355]

Where is question 15? I can find the solution on bio-25 but no question prior.

[mary.ws.sh7355]

re. unit 4 question 5, I meant unit 4, question 8. It says "note that answer choice D is not consistent with negative feedback... Potentially, answer choice D would usually be correct when X and Z are in relatively low concentrations". Is answer D the right answer choice?

[goldstanda3269]

Also, whats the answer for Unit 5 Question 9? is it A? that is if the green dotted lines of positive stimulatory feedback are considered direct conversions.

No, positive feedback does not mean that A is converted to B. Positive feedback means that A increases the concentration of B and then B (feedback) increases (positive) the concentration of A. This idea will be explored in detail in BIO 6.3.7. If B decreases the concentration of A, then that is called 'negative feedback'.

Answer choice D is correct.

Also, I understand why you are asking for the answer. I just noticed that the worked solutions on pages BIO-22, 23, 24, 25 are all off by one number. You are asking about Question 9, well the first worked solution on BIO-22 says Question 10 but it should say Question 9. Please carefully read that worked solution to see if you now understand Question 9. This numbering typo for the solutions will be corrected in the next edition.

[goldstanda3269]

Where is question 15? I can find the solution on bio-25 but no question prior.

As above, the worked solution for "Question 15" is actually the worked solution for Question 14. As you correctly stated, there is no Question 15.

[goldstanda3269]

re. unit 4 question 5, I meant unit 4, question 8. It says "note that answer choice D is not consistent with negative feedback... Potentially, answer choice D would usually be correct when X and Z are in relatively low concentrations". Is answer D the right answer choice?

The correct answer is B. The last sentence in the first paragraph of BIO-19 gives the solution:
S --> V

D is not correct: "note that answer choice D is not consistent with negative feedback" is stated because this question was about negative feedback and we knew that some students might choose D.

"Potentially, answer choice D would usually be correct when X and Z are in relatively low concentrations" was stated because this is the opposite of the question: note that in the question X and Z are in relatively HIGH concentrations.

[mary.ws.sh7355]

That makes it all much more clearer. Thanks for the answer!