BRS Biochemistry, Molecular Biology,
Genetics - Questions
The largest amount of stored energy in the body>>> Adipose triacylglycerols contain the largest amount
of stored energy in humans, followed by protein (even though loss of too much protein will lead to
death), muscle glycogen, and liver glycogen (see Table 1.1).
The energy source reserved for strenuous muscular activity>>> Muscle glycogen is used for energy
during exercise. The glycogen is degraded to a form of glucose that can enter metabolic pathways for
energy generation. Because exercise is strenuous, muscle requires large amounts of energy, and this can
be generated at the fastest rate by converting muscle glycogen to pathway precursors within the
muscle. Liver glycogen will produce glucose that enters the circulation. Once in the circulation, the
muscle can take up that glucose and use it to generate energy; however, the rate of energy generation
from liver-derived glucose is much slower than that from muscle-derived glucose.
The primary source of carbon for maintaining blood glucose levels during an overnight fast>>> Liver
glycogenolysis is the major process for maintaining blood glucose levels after an overnight fast. The
muscle cannot export glucose to contribute to the maintenance of blood glucose levels, and fatty acid
carbons cannot be utilized for the net synthesis of glucose.
The major precursor of urea in the urine>>> The nitrogen in amino acids derived from protein is
converted to urea and excreted in the urine. Uric acid, another excretion product that contains nitrogen,
is derived from purine bases (found in nucleic acids), not from protein.
A 32-year-old male is on a weight-maintenance diet, so he does not want to lose or gain any weight.
Which amino acid must be present in the diet so the patient does not go into a negative nitrogen
balance?
(A) Alanine
(B) Arginine
(C) Glycine
(D) Threonine
(E) Serine>>> D. The lack of one essential amino acid will lead to a negative nitrogen balance due to
increased protein degradation to supply that amino acid for the ongoing protein synthesis. Of the amino
acids listed, only threonine is an essential amino acid (alanine can be synthesized from pyruvate [which
can be derived from glucose], arginine is produced in the urea cycle using aspartic acid and the amino
acid ornithine, glycine is derived from serine, and serine is derived from 3-phosphoglycerate, which can
be produced from glucose).
,After a fast of a few days,
ketone bodies become an
important fuel>>> B. The brain begins to use ketone bodies when levels start to rise after 3 to 5 days of
fasting. Normally, the brain will use only glucose as a fuel (most fatty acids cannot
cross the blood-brain barrier to be metabolized by the brain), but when ketone bodies are elevated in
the blood, they can enter the brain and be used for energy.
Ketone bodies are used
as a fuel after an overnight
fast>>> C. Skeletal muscle oxidizes ketone bodies, which are synthesized in the liver from fatty acids
derived from adipose tissue. As the fast continues, the muscle will switch to oxidizing fatty acids, which
allows ketone body levels to rise such that the brain will begin using them as an energy source.
Fatty acids are not a significant fuel source at any time>>> D. Oxidation of fatty acids occurs in
mitochondria. Red blood cells lack mitochondria and therefore cannot use fatty acids. The brain will not
transport most fatty acids across the blood-brain barrier (the essential fatty acids are a notable
exception). Therefore, the brain cannot use fatty acids as an energy source. The brain does, however,
synthesize its own fatty acids, and will oxidize those fatty acids when appropriate. Red blood cells can
never use fatty acids as an energy source due to their lack of mitochondria.
During starvation, this tissue uses amino acids to maintain blood glucose levels>>> A. The liver converts
amino acids to blood glucose by gluconeogenesis. The other substrates for gluconeogenesis are lactate
from the metabolism of glucose within the red blood cells and glycerol from the breakdown of
triacylglycerol to free fatty acids and glycerol. Neither the brain, nor the skeletal muscle, nor the red
blood cell can export glucose into the circulation.
This tissue converts lactate
from muscle to a fuel for
other tissues>>> A. Exercising muscle produces lactate, which the liver can convert to glucose by
gluconeogenesis. Blood glucose is oxidized by red blood cells and other tissues. Only the liver and kidney
(to a small extent) can release free glucose into the circulation for use by other tissues
A young woman (5' 3" tall, 1.6 m) who has a
sedentary job and does not exercise consulteda physician about her weight, which was 110 lb(50 kg). A
dietary history indicates that she eatsapproximately 100 g of carbohydrate, 20 g of protein, and 40 g of
fat daily.
What is this woman's BMI?
,(A) 16.5
(B) 17.5
(C) 18.5
(D) 19.5
(E) 20.5>>> D. The BMI is calculated by dividing the weight of the individual (in kilograms) by the square
of the height of the individual (in meters). For this woman, BMI 5 50/1.62 5 19.5
A young woman (5' 3" tall, 1.6 m) who has a sedentary job and does not exercise consulteda physician
about her weight, which was 110 lb(50 kg). A dietary history indicates that she eatsapproximately 100 g
of carbohydrate, 20 g of protein, and 40 g of fat daily.
According to the woman's BMI, into what classification does her weight and height
place her?
(A) Underweight
(B) Normal range
(C) Overweight (preobese)
(D) Class I obese range
(E) Class II obese range>>> B. According to Table 1.2, a BMI of 19.5 places the woman at the lower end
of the normal range. Underweight is indicated by a BMI of ,18.5; preobesity occurs above a BMI of 25,
but ,30. Class I obesity is indicated by a BMI between 30 and 35, and class II obesity by a BMI between
35 and 40.
A young woman (5' 3" tall, 1.6 m) who has a sedentary job and does not exercise consulteda physician
about her weight, which was 110 lb(50 kg). A dietary history indicates that she eatsapproximately 100 g
of carbohydrate, 20 g of protein, and 40 g of fat daily.
How many calories (kcal) does this woman
consume each day?
(A) 1,440
(B) 1,340
(C) 940
(D) 840
, (E) 640>>> D. The woman consumes 400 calories (kcal) of carbohydrate (100 g 3 4 kcal/g), 80 calories of
protein (20 3 4), and 360 calories of fat (40 3 9) for a total of 840 calories daily.
A young woman (5' 3" tall, 1.6 m) who has a
sedentary job and does not exercise consulteda physician about her weight, which was 110 lb(50 kg). A
dietary history indicates that she eatsapproximately 100 g of carbohydrate, 20 g of protein, and 40 g of
fat daily.
What is the woman's approximate DEE in
calories (kilocalories) per day at this weight?
(A) 1,200
(B) 1,560
(C) 1,800
(D) 2,640
(E) 3,432>>> B. This woman's DEE is 1,560 calories (kcal). DEE equals BMR plus physical activity. Her
weight is 110 lb/2.2 5 50 kg. Her BMR (about 24 kcal/kg) is 50 kg 3 24 5 1,200 kcal/day. She is sedentary
and needs only 360 additional kcal (30% of her BMR) to support her physical activity. Therefore, she
needs 1,200 1 360 5 1,560 kcal each day.
A young woman (5' 3" tall, 1.6 m) who has a
sedentary job and does not exercise consulteda physician about her weight, which was 110 lb(50 kg). A
dietary history indicates that she eatsapproximately 100 g of carbohydrate, 20 g of protein, and 40 g of
fat daily.
On the basis of the woman's current weight, diet, and sedentary lifestyle, which one of the following
does the physician correctly recommend that she should undertake?
(A) Increase her exercise level
(B) Decrease her protein intake
(C) Increase her caloric intake
(D) Decrease her fat intake to ,30% of her
total calories
(E) Decrease her caloric intake>>> C. Because her caloric intake (840 kcal/day) is less than her
expenditure (1,560 kcal/day), the woman is losing weight. She needs to increase her caloric intake.
Exercise would cause her to lose more weight. She is probably in negative nitrogen balance because her
Genetics - Questions
The largest amount of stored energy in the body>>> Adipose triacylglycerols contain the largest amount
of stored energy in humans, followed by protein (even though loss of too much protein will lead to
death), muscle glycogen, and liver glycogen (see Table 1.1).
The energy source reserved for strenuous muscular activity>>> Muscle glycogen is used for energy
during exercise. The glycogen is degraded to a form of glucose that can enter metabolic pathways for
energy generation. Because exercise is strenuous, muscle requires large amounts of energy, and this can
be generated at the fastest rate by converting muscle glycogen to pathway precursors within the
muscle. Liver glycogen will produce glucose that enters the circulation. Once in the circulation, the
muscle can take up that glucose and use it to generate energy; however, the rate of energy generation
from liver-derived glucose is much slower than that from muscle-derived glucose.
The primary source of carbon for maintaining blood glucose levels during an overnight fast>>> Liver
glycogenolysis is the major process for maintaining blood glucose levels after an overnight fast. The
muscle cannot export glucose to contribute to the maintenance of blood glucose levels, and fatty acid
carbons cannot be utilized for the net synthesis of glucose.
The major precursor of urea in the urine>>> The nitrogen in amino acids derived from protein is
converted to urea and excreted in the urine. Uric acid, another excretion product that contains nitrogen,
is derived from purine bases (found in nucleic acids), not from protein.
A 32-year-old male is on a weight-maintenance diet, so he does not want to lose or gain any weight.
Which amino acid must be present in the diet so the patient does not go into a negative nitrogen
balance?
(A) Alanine
(B) Arginine
(C) Glycine
(D) Threonine
(E) Serine>>> D. The lack of one essential amino acid will lead to a negative nitrogen balance due to
increased protein degradation to supply that amino acid for the ongoing protein synthesis. Of the amino
acids listed, only threonine is an essential amino acid (alanine can be synthesized from pyruvate [which
can be derived from glucose], arginine is produced in the urea cycle using aspartic acid and the amino
acid ornithine, glycine is derived from serine, and serine is derived from 3-phosphoglycerate, which can
be produced from glucose).
,After a fast of a few days,
ketone bodies become an
important fuel>>> B. The brain begins to use ketone bodies when levels start to rise after 3 to 5 days of
fasting. Normally, the brain will use only glucose as a fuel (most fatty acids cannot
cross the blood-brain barrier to be metabolized by the brain), but when ketone bodies are elevated in
the blood, they can enter the brain and be used for energy.
Ketone bodies are used
as a fuel after an overnight
fast>>> C. Skeletal muscle oxidizes ketone bodies, which are synthesized in the liver from fatty acids
derived from adipose tissue. As the fast continues, the muscle will switch to oxidizing fatty acids, which
allows ketone body levels to rise such that the brain will begin using them as an energy source.
Fatty acids are not a significant fuel source at any time>>> D. Oxidation of fatty acids occurs in
mitochondria. Red blood cells lack mitochondria and therefore cannot use fatty acids. The brain will not
transport most fatty acids across the blood-brain barrier (the essential fatty acids are a notable
exception). Therefore, the brain cannot use fatty acids as an energy source. The brain does, however,
synthesize its own fatty acids, and will oxidize those fatty acids when appropriate. Red blood cells can
never use fatty acids as an energy source due to their lack of mitochondria.
During starvation, this tissue uses amino acids to maintain blood glucose levels>>> A. The liver converts
amino acids to blood glucose by gluconeogenesis. The other substrates for gluconeogenesis are lactate
from the metabolism of glucose within the red blood cells and glycerol from the breakdown of
triacylglycerol to free fatty acids and glycerol. Neither the brain, nor the skeletal muscle, nor the red
blood cell can export glucose into the circulation.
This tissue converts lactate
from muscle to a fuel for
other tissues>>> A. Exercising muscle produces lactate, which the liver can convert to glucose by
gluconeogenesis. Blood glucose is oxidized by red blood cells and other tissues. Only the liver and kidney
(to a small extent) can release free glucose into the circulation for use by other tissues
A young woman (5' 3" tall, 1.6 m) who has a
sedentary job and does not exercise consulteda physician about her weight, which was 110 lb(50 kg). A
dietary history indicates that she eatsapproximately 100 g of carbohydrate, 20 g of protein, and 40 g of
fat daily.
What is this woman's BMI?
,(A) 16.5
(B) 17.5
(C) 18.5
(D) 19.5
(E) 20.5>>> D. The BMI is calculated by dividing the weight of the individual (in kilograms) by the square
of the height of the individual (in meters). For this woman, BMI 5 50/1.62 5 19.5
A young woman (5' 3" tall, 1.6 m) who has a sedentary job and does not exercise consulteda physician
about her weight, which was 110 lb(50 kg). A dietary history indicates that she eatsapproximately 100 g
of carbohydrate, 20 g of protein, and 40 g of fat daily.
According to the woman's BMI, into what classification does her weight and height
place her?
(A) Underweight
(B) Normal range
(C) Overweight (preobese)
(D) Class I obese range
(E) Class II obese range>>> B. According to Table 1.2, a BMI of 19.5 places the woman at the lower end
of the normal range. Underweight is indicated by a BMI of ,18.5; preobesity occurs above a BMI of 25,
but ,30. Class I obesity is indicated by a BMI between 30 and 35, and class II obesity by a BMI between
35 and 40.
A young woman (5' 3" tall, 1.6 m) who has a sedentary job and does not exercise consulteda physician
about her weight, which was 110 lb(50 kg). A dietary history indicates that she eatsapproximately 100 g
of carbohydrate, 20 g of protein, and 40 g of fat daily.
How many calories (kcal) does this woman
consume each day?
(A) 1,440
(B) 1,340
(C) 940
(D) 840
, (E) 640>>> D. The woman consumes 400 calories (kcal) of carbohydrate (100 g 3 4 kcal/g), 80 calories of
protein (20 3 4), and 360 calories of fat (40 3 9) for a total of 840 calories daily.
A young woman (5' 3" tall, 1.6 m) who has a
sedentary job and does not exercise consulteda physician about her weight, which was 110 lb(50 kg). A
dietary history indicates that she eatsapproximately 100 g of carbohydrate, 20 g of protein, and 40 g of
fat daily.
What is the woman's approximate DEE in
calories (kilocalories) per day at this weight?
(A) 1,200
(B) 1,560
(C) 1,800
(D) 2,640
(E) 3,432>>> B. This woman's DEE is 1,560 calories (kcal). DEE equals BMR plus physical activity. Her
weight is 110 lb/2.2 5 50 kg. Her BMR (about 24 kcal/kg) is 50 kg 3 24 5 1,200 kcal/day. She is sedentary
and needs only 360 additional kcal (30% of her BMR) to support her physical activity. Therefore, she
needs 1,200 1 360 5 1,560 kcal each day.
A young woman (5' 3" tall, 1.6 m) who has a
sedentary job and does not exercise consulteda physician about her weight, which was 110 lb(50 kg). A
dietary history indicates that she eatsapproximately 100 g of carbohydrate, 20 g of protein, and 40 g of
fat daily.
On the basis of the woman's current weight, diet, and sedentary lifestyle, which one of the following
does the physician correctly recommend that she should undertake?
(A) Increase her exercise level
(B) Decrease her protein intake
(C) Increase her caloric intake
(D) Decrease her fat intake to ,30% of her
total calories
(E) Decrease her caloric intake>>> C. Because her caloric intake (840 kcal/day) is less than her
expenditure (1,560 kcal/day), the woman is losing weight. She needs to increase her caloric intake.
Exercise would cause her to lose more weight. She is probably in negative nitrogen balance because her
