BIO 155 Lab Practical Study Guide LATEST ACTUAL
EXAM WITH VERIFIED QUESTIONS & CORRECT
ANSWERS
Question 1.
Describe the laboratory test used to indicate the presence of reducing sugars and interpret the results.
ANSWER
Reducing Sugars - Benedict's reagent; blue color presence of copper ions (Cu 2+), must be
heated at 80 degrees (C), when heated carbonyl group is oxidized and copper ions are reduced
as a result produces a color change from blue to green to yellow to orange and reddish brown
depending on concentration of reducing sugars present.
Question 2.
Describe the laboratory test used to indicate the presence of proteins and interpret the results.
ANSWER
Biuret reagent indicates the presence of proteins when its color changes from blue to violet.
Question 3.
Distinguish between qualitative and quantitative datas.
ANSWER
Quantitative data- elating to, measuring, or measured by the quantity of something rather
than its quality; Qualitative data-Deals with descriptions.
Data can be observed but not measured.
Colors, textures, smells, tastes, appearance, beauty, etc.
Question 4.
Describe the process of spectrophotometry
ANSWER
scientists determine the presence and concentration of dissolved chemicals in solutions using
spectrophotometry; a technique based on the principle that each atom, molecule, or chemical
bond absorbs a unique pattern of wavelengths of light;
,Question 5.
Light source
ANSWER
the light source produces white light which is a combination of all visible wavelengths
Question 6.
Filter
ANSWER
the filter is adjusted to match the wavelength being used
Question 7.
Sample
ANSWER
sample solution is contained only the solvent used to dissolve the chemical you are analyzing.
A blank is used to calibrate the spectrophotometer for the solution and wavelength used in the
experiment
Question 8.
Photodetector
ANSWER
Any light which is transmitted through the sample strikes the photodetector. The
photodetector converts the light energy to electricity. The electric current is measured and the
results displayed on a scale of absorbance or transmittance values.
Question 9.
Compare and contrast competitive and non-competitive enzyme inhibitors
ANSWER
Competitive Enzyme Inhibitors- when a molecule that is structurally similar to the substrate for
a particular reaction competes for a position at the active site on the enzyme; Non-competitive-
binds to a site that is not the active site, changing the nature of the enzyme so that its catalytic
properties are lost in two ways, physically blocks the access to the active site or conformational
change in the protein.
, Question 10.
Active site
ANSWER
the region that binds with the binds with the substrate forming a temporary enzyme-substrate
complex
Question 11.
Phenylthiourea
ANSWER
specific inhibitor used in the experiment, PTU is known to combine with the copper in catechol
oxidase and inhibit its enzymatic activity.
Question 12.
Describe a method for determining whether an inhibitor is competitive
ANSWER
Catechol
Question 13.
Define Enzymes and discuss their role in metabolism
ANSWER
they act as catalysts, substances that speed up chemical reactions without being destroyed or
altered during the process, lowers the activation energy.
Question 14.
Discuss the effect of enzyme concentration on enzymatic activity
ANSWER
greater the enzyme concentration more enzymatic activity.
EXAM WITH VERIFIED QUESTIONS & CORRECT
ANSWERS
Question 1.
Describe the laboratory test used to indicate the presence of reducing sugars and interpret the results.
ANSWER
Reducing Sugars - Benedict's reagent; blue color presence of copper ions (Cu 2+), must be
heated at 80 degrees (C), when heated carbonyl group is oxidized and copper ions are reduced
as a result produces a color change from blue to green to yellow to orange and reddish brown
depending on concentration of reducing sugars present.
Question 2.
Describe the laboratory test used to indicate the presence of proteins and interpret the results.
ANSWER
Biuret reagent indicates the presence of proteins when its color changes from blue to violet.
Question 3.
Distinguish between qualitative and quantitative datas.
ANSWER
Quantitative data- elating to, measuring, or measured by the quantity of something rather
than its quality; Qualitative data-Deals with descriptions.
Data can be observed but not measured.
Colors, textures, smells, tastes, appearance, beauty, etc.
Question 4.
Describe the process of spectrophotometry
ANSWER
scientists determine the presence and concentration of dissolved chemicals in solutions using
spectrophotometry; a technique based on the principle that each atom, molecule, or chemical
bond absorbs a unique pattern of wavelengths of light;
,Question 5.
Light source
ANSWER
the light source produces white light which is a combination of all visible wavelengths
Question 6.
Filter
ANSWER
the filter is adjusted to match the wavelength being used
Question 7.
Sample
ANSWER
sample solution is contained only the solvent used to dissolve the chemical you are analyzing.
A blank is used to calibrate the spectrophotometer for the solution and wavelength used in the
experiment
Question 8.
Photodetector
ANSWER
Any light which is transmitted through the sample strikes the photodetector. The
photodetector converts the light energy to electricity. The electric current is measured and the
results displayed on a scale of absorbance or transmittance values.
Question 9.
Compare and contrast competitive and non-competitive enzyme inhibitors
ANSWER
Competitive Enzyme Inhibitors- when a molecule that is structurally similar to the substrate for
a particular reaction competes for a position at the active site on the enzyme; Non-competitive-
binds to a site that is not the active site, changing the nature of the enzyme so that its catalytic
properties are lost in two ways, physically blocks the access to the active site or conformational
change in the protein.
, Question 10.
Active site
ANSWER
the region that binds with the binds with the substrate forming a temporary enzyme-substrate
complex
Question 11.
Phenylthiourea
ANSWER
specific inhibitor used in the experiment, PTU is known to combine with the copper in catechol
oxidase and inhibit its enzymatic activity.
Question 12.
Describe a method for determining whether an inhibitor is competitive
ANSWER
Catechol
Question 13.
Define Enzymes and discuss their role in metabolism
ANSWER
they act as catalysts, substances that speed up chemical reactions without being destroyed or
altered during the process, lowers the activation energy.
Question 14.
Discuss the effect of enzyme concentration on enzymatic activity
ANSWER
greater the enzyme concentration more enzymatic activity.
