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LAMC
BIOLOGY

Bio3: Quiz 2 Study Guide - Fall 2006

Topics:
Note: The quiz will contain questions that are similar, but not identical to, the study questions below and the lab review sheet questions.
The quiz will cover lab topics for Ex. 3 (Macromolecules), 4 (Using the Microscope) and 5 (Enzymes).
- Identifying the appropriate tests to use to determine if a solution contains a sugar, starch, protein or lipid
- Interpreting the results of Benedict’s, Iodine and Biuret tests
- Identifying the parts and their purposes on a compound and dissecting microscope
- Identifying the differences and similarities between a compound and dissecting microscope
- Identifying the difference between substrate, enzyme and product.
- Explaining how reaction rate changes with a change in enzyme concentration, substrate concentration, salt concentration, pH, and temperature.

Study Questions:

1. Benedict’s reagent is used to detect for the presence of what type of molecules?

2. A solution of starch gives a negative result with Benedict’s test.  But after hydrolyzing the starch solution with an acid (HCl), the Benedict’s test gave a positive result.  Why?

3. An unknown food substance gives a positive result with iodine and Biuret, but a negative result with Benedict’s test.  Also, rubbing a piece of that food onto paper did not cause the paper to become translucent.  What macromolecules are detectable in this unknown food?

4. The lens connected to the nosepiece on the microscope is called the ___________________.

5. When viewing objects under the highest magnification, you should only use the __________________ knob to adjust the clarity of the image because _____________________________________.

6. How is the image viewed through a compound microscope different from that viewed through a dissecting microscope?

7. What is the total magnification of an object viewed through the 10x objective lens on a compound microscope?

8. In the following equation, identify the enzyme, substrate and product by writing in the correct word in the spaces provided.

sucrose  ---sucrase -->   glucose + fructose

sucrose: ______________      sucrase: _________________             glucose + fructose: _______________

9. In the Enzyme lab, you added different amounts of potato extract to a colorless substrate to produce a reddish brown product. What was the purpose of the potato extract?  If you had three test tubes, with low, medium and high amounts of potato extract, in which tube would you expect to see the darkest color? Why?

Answers:

1. small sugars (monosaccharides and disaccharides)

2. Starch is a polysaccharide made up of glucose molecules.  Adding the acid separated the starch into glucose, which then gave a positive result with the Benedict’s test.

3. Starch and protein

4. objective lens 

5. fine focus knob; using the coarse focus knob will cause the objective lens to move too much and may scratch the lens or cause the slide to break.

6. A compound scope shows a 2-D image and the object is flipped upside down.  A dissecting scope shows a 3-D image and the object is oriented in the same direction as on the slide.

7. 100x (need to multiply by the 10x on the ocular lens)

8. Sucrose: substrate;              sucrase: enzyme;         glucose + fructose: product

9. The potato extract was the source of the enzyme.  The tube with a high amount of potato extract would yield the darkest color because a greater concentration of enzyme will result in a higher reaction rate.

©2003-2004 Dilek Sanver-Wang, MS
Los Angeles, CA USA.  All Rights Reserved.