BIOC385 Exam 3 Questions and Answers Already Passed Latest Update 2025-2026
Explain why glyphosate works faster in the summer after rain than after two weeks without rain.
- Answers It works faster after it rains because the plants rapidly use up phenylalanine, which
becomes limiting in the presence of glyphosate.
Nitrogen in biological compounds ultimately comes from what source? - Answers nitrogen gas
What is the mechanism by which Roundup works? - Answers Glyphosate is a competitive
inhibitor to plant EPSP synthase.
What molecule signals the endothelial cell to produce NO? - Answers acetylcholine
The shikimate pathway can be defined as the pathway that involves the - Answers condensation
of phosphoenolpyruvate and erythrose-4-phosphate.
Defects in nucleotide metabolism that lead to a buildup of uric acid cause the disease gout.
Select the TWO true statements below regarding potential treatments for gout. - Answers
Supplying humans with the enzyme urate oxidase theoretically could be effective in reducing
uric acid levels.
An inhibitor of xanthine oxidase, such as allopurinol, will limit the conversion of hypoxanthine to
uric acid, and could be effective in reducing uric acid levels.
Which of the following is the product of uracil degradation? - Answers β-alanine
Analysis of enzyme activities in a cell in the absence and presence of AMP and GMP is
completed. Which enzyme would show lower activity when AMP is added but not when GMP is
added? - Answers adenylosuccinate synthase
If an alteration occurred in the activity site of the R1 subunit of E. coli ribonucleotide reductase
that allowed dATP to bind but precluded ATP binding to the site, a possible result would be that
ribonucleotide reductase - Answers would be decreased when dATP bound both the activity and
specificity sites.
A compound is added to a cell and dihydrofolate reductase activity is reduced. If this compound
is __________, it can be predicted that a similar result would be seen if __________ were added
instead. - Answers methotrexate; aminopterin
Glucose-6P is critical in metabolic homeostasis, which mechanism controls metabolic flux? -
Answers enzyme levels
What is the biochemical explanation for why rapid weight loss is reported with protein-rich diets?
- Answers Amino acid degradation results in urea production to remove excess NH4+, so mostly
water weight loss.
, What is the most immediate fuel source to regenerate ATP used up for muscle contraction after
the first few seconds of a 200-meter sprint? - Answers muscle phosphocreatine
Based on what is known about neuronal control of energy metabolism in humans, why is it so
hard to lose weight by dieting? More than one answer may be correct. - Answers Ghrelin levels
increase when your stomach is empty, which is one of the objectives of dieting, yet ghrelin
signals to the brain to eat more; metabolize less. The net result is you always feel hungry and
eventually give in.
Leptin levels decrease when fat deposits decrease, which in turn, decreases the signal to eat
less; metabolize more. The net result is that you eat more; metabolize less because your body
thinks you are starving.
Food can be addictive to some people, much like narcotics. Therefore, the reward they get from
binge eating leads to food cravings during diet-induced "withdrawal."
Insulin levels decrease when blood sugar decrease, which is one of the objectives of dieting,
therefore it decreases the signal to eat less; metabolize more. The net result is that you eat
more; metabolize less because your body thinks you are starving for sugar.
PYY3-36 signals to the brain that you have food in your stomach and it inhibits the signal to the
brain to eat more; metabolize less. Dieters are often so hungry that they eat too fast and the
PYY3-36 inhibitory signal fails.
Metabolic homeostasis relies on maintaining - Answers optimal metabolite concentrations.
Which reaction explains why animals fed N-Asp will accumulate N-labeled proteins? - Answers
Aspartate + a-keto acid + oxaloacetate + a-amino acid
The human genome encodes three types of
enzymes in the ubiquitinating pathway, all with
multiple variant gene copies; 11 E1 variant genes, 26 E2 variant genes and over 500 E3 variant
genes. What does this tell you about the biochemistry of the ubiquitination process? - Answers
That recognition of distinct target proteins requires specific E3 sequences; therefore many E3
proteins.
Phenylketonuria is caused by a defect in the enzyme phenylalanine hydroxylase (1). The
Explain why glyphosate works faster in the summer after rain than after two weeks without rain.
- Answers It works faster after it rains because the plants rapidly use up phenylalanine, which
becomes limiting in the presence of glyphosate.
Nitrogen in biological compounds ultimately comes from what source? - Answers nitrogen gas
What is the mechanism by which Roundup works? - Answers Glyphosate is a competitive
inhibitor to plant EPSP synthase.
What molecule signals the endothelial cell to produce NO? - Answers acetylcholine
The shikimate pathway can be defined as the pathway that involves the - Answers condensation
of phosphoenolpyruvate and erythrose-4-phosphate.
Defects in nucleotide metabolism that lead to a buildup of uric acid cause the disease gout.
Select the TWO true statements below regarding potential treatments for gout. - Answers
Supplying humans with the enzyme urate oxidase theoretically could be effective in reducing
uric acid levels.
An inhibitor of xanthine oxidase, such as allopurinol, will limit the conversion of hypoxanthine to
uric acid, and could be effective in reducing uric acid levels.
Which of the following is the product of uracil degradation? - Answers β-alanine
Analysis of enzyme activities in a cell in the absence and presence of AMP and GMP is
completed. Which enzyme would show lower activity when AMP is added but not when GMP is
added? - Answers adenylosuccinate synthase
If an alteration occurred in the activity site of the R1 subunit of E. coli ribonucleotide reductase
that allowed dATP to bind but precluded ATP binding to the site, a possible result would be that
ribonucleotide reductase - Answers would be decreased when dATP bound both the activity and
specificity sites.
A compound is added to a cell and dihydrofolate reductase activity is reduced. If this compound
is __________, it can be predicted that a similar result would be seen if __________ were added
instead. - Answers methotrexate; aminopterin
Glucose-6P is critical in metabolic homeostasis, which mechanism controls metabolic flux? -
Answers enzyme levels
What is the biochemical explanation for why rapid weight loss is reported with protein-rich diets?
- Answers Amino acid degradation results in urea production to remove excess NH4+, so mostly
water weight loss.
, What is the most immediate fuel source to regenerate ATP used up for muscle contraction after
the first few seconds of a 200-meter sprint? - Answers muscle phosphocreatine
Based on what is known about neuronal control of energy metabolism in humans, why is it so
hard to lose weight by dieting? More than one answer may be correct. - Answers Ghrelin levels
increase when your stomach is empty, which is one of the objectives of dieting, yet ghrelin
signals to the brain to eat more; metabolize less. The net result is you always feel hungry and
eventually give in.
Leptin levels decrease when fat deposits decrease, which in turn, decreases the signal to eat
less; metabolize more. The net result is that you eat more; metabolize less because your body
thinks you are starving.
Food can be addictive to some people, much like narcotics. Therefore, the reward they get from
binge eating leads to food cravings during diet-induced "withdrawal."
Insulin levels decrease when blood sugar decrease, which is one of the objectives of dieting,
therefore it decreases the signal to eat less; metabolize more. The net result is that you eat
more; metabolize less because your body thinks you are starving for sugar.
PYY3-36 signals to the brain that you have food in your stomach and it inhibits the signal to the
brain to eat more; metabolize less. Dieters are often so hungry that they eat too fast and the
PYY3-36 inhibitory signal fails.
Metabolic homeostasis relies on maintaining - Answers optimal metabolite concentrations.
Which reaction explains why animals fed N-Asp will accumulate N-labeled proteins? - Answers
Aspartate + a-keto acid + oxaloacetate + a-amino acid
The human genome encodes three types of
enzymes in the ubiquitinating pathway, all with
multiple variant gene copies; 11 E1 variant genes, 26 E2 variant genes and over 500 E3 variant
genes. What does this tell you about the biochemistry of the ubiquitination process? - Answers
That recognition of distinct target proteins requires specific E3 sequences; therefore many E3
proteins.
Phenylketonuria is caused by a defect in the enzyme phenylalanine hydroxylase (1). The
