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livestrong136 livestrong136
wrote...
Posts: 324
Rep: 7 0
10 years ago
Looking from the diagram (attached)?

1. Which tube was used as a positive control for the IKI test?


2. Which test tube was used as a positive control for the Benedict’s test?
 

3. Which test tubes were used as negative controls in this experiment? Explain?
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wrote...
Educator
10 years ago
You need to do a better job asking your question. No mention of the exercise or what you've done to try answering it. I have attached what might be helpful...
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livestrong136 Author
wrote...
10 years ago Edited: 10 years ago, livestrong136
Sorry, its Activity 1: Assessing Starch Digestion by Salivary Amylase
Post Merge: 10 years ago

is the answer for #1; tubes 1, 5, 7, 8.

for #2, is it 2, 3, 6

for #3, is it, 1, 4, 5

I am really confused?
wrote...
Educator
10 years ago
I'll look into it tomorrow... PM me if I forget.
wrote...
Educator
10 years ago
Thanks for the reminder. See if this helps:

Tubes 2, 6, and 7 showed the effect of pH on amylase activity. The results of this experiment indicate that the activity maximum of amylase is at pH 7.0, whereas pH 2.0 and pH 9.0 demonstrated very little activity.

In this experiment, pH 7.0 showed the highest level of amylase activity. Tube 3 showed that amylase did not contain maltose contamination. Tubes 3, 4, and 5 showed that water had no starch or maltose contamination. Tube 3 directly showed that water did not have maltose or starch contamination. Tube 4 was a starch control (with the same water) that showed no maltose, and tube 5 was a maltose control (also with water) that showed no starch.

If control tubes 3, 4, or 5 were not done, then what is perceived as digestion might really be starch or maltose contamination. Saliva would not be active in the stomach because the stomach pH is too low. Boiling inactivates, or denatures, enzymes.
livestrong136 Author
wrote...
10 years ago
first, thnx for replying. Secondly, I understand your explanation, but what do the questions mean. Like what does it mean "positive control for IKI test"? or "Positive control for Benedict's test"??
wrote...
Educator
10 years ago
A positive control is when you test your experiment against something where you know what the effects will be, whereas a negative control would be when you test the experiment with something you know will have no effect.
wrote...
10 years ago
Positive control:
(a) A positive control is a level of treatment that is expected to result in a change in the value of a dependent variable. The purpose of the positive control is to serve as proof that the experiment can produce a positive result, i.e., a change in the value of a dependent variable.

(b) If a positive control is not included in a protocol then non-change in the value of a dependent variable may be due to:

(i) a negative result,

(ii) a protocol that is not capable of producing a positive result (a.k.a., systematic error), or

(iii) experimental error in the course of performing the protocol

(c) Of course, the latter could occur for individual measurements rather than for the entire experiment, but that is why one does more than one replication.

Negative control:
(a) The negative control level of treatment often corresponds with the control-treatment level of treatment.

(b) The negative control is supposed to result in a lack of change (or some baseline display value) in the dependent variable. This way one may determine whether experimental levels of treatment produce a change in the dependent variable.

(c) The negative control also serves as proof that a given protocol is capable of giving baseline results.

(i) That is, if a given level of treatment produces a given value for the dependent variable, we will only know if that value is a consequence of varying the independent variable if we have something with which to compare that value of the dependent variable.
livestrong136 Author
wrote...
10 years ago
Can you please just give me the exact answer for the 3 questions. It's a little confusing, ill see your answer and interpret them and understand when I match it to my data. Thnx, and sorry if I sound like I just want the answer.
wrote...
Educator
10 years ago
Mind updating us on the answers to these, livestrong136?
livestrong136 Author
wrote...
10 years ago
1. 5

2. 6

3. 2
wrote...
Educator
10 years ago
Thank you, sir!
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