USABO Open Exam Questions and
Answers
Assume a person is placed on cortisol medication, a
glucocorticoid. How would you expect the rates of ACTH and
CRF hormone production to change in the person?
A. ACTH production would increase, CRF production would
increase
B. ACTH production would increase, CRF production would
decrease
C. ACTH production would decrease, CRF production would
decrease
D. ACTH production would decrease, CRF production would
increase
E. ACTH and CRF production would not change - Correct
Answers ✅D. ACTH production would decrease, CRF
production would increase
The adrenal cortex reacts to stress and responds to endocrine
signals. Stressful stimuli cause the hypothalamus to secrete a
releasing hormone that stimulates the anterior pituitary to
release the tropic hormone ACTH. When ACTH reaches its
target via the bloodstream, it stimulates cells of the adrenal
cortex to synthesize and secrete a family of steroids called
corticosteriods [There are two main types in humans:
glucocorticoids, such as cortisol and the mineralocorticoids,
such as aldosterone]. The elevated levels of corticosteriods in
the blood suppress the secretion of ACTH. The production of
ACTH therefore decreases and CRF, corticoptropin-releasing
factor/hormone, increases.
,USABO Open Exam Questions and
Answers
Carbon particles were injected into the blood of mice. In
which of the following places would you most likely find the
particles?
A. In the glomerular filtrate
B. In the adipose tissue of the liver
C. In monocytes of the spleen
D. In plasma cells of the bone marrow
E. In the loops of Henle - Correct Answers ✅C. In
monocytes of the spleen
Monocytes constitute 5% of leukocytes, which are part of a
phagocytic defense (ingestion of invading organisms by white
blood cells). New monocytes circulate in the blood for only a
few hours and then migrate into tissues, developing into
large macrophages. Organs of the lymphatic system that trap
"foreign" molecules and particles are the spleen, lymph
nodes, adenoid, tonsil, appendix and Peyer's patch, which is
located in the small intestine.
Kidneys provide osmoregulation for the body. Consumption of
which nutrient creates the greatest need for osmoregulation?
A. Cellulose
B. Fat
,USABO Open Exam Questions and
Answers
C. Oil
D. Protein
E. Starch - Correct Answers ✅D. Protein
Osmoregulation is the control of water balance in organisms
living in hypertonic, hypotonic, or terrestrial environments.
Osmoregulation also holds the concentration of solutes in the
blood (and indirectly, the concentration in tissues) at
appropriate levels. The kidney has two distinct regions, the
outer renal cortex and the inner renal medulla, which are
packed with nephrons. Nephrons consist of the glomerulus
and Bowman's capsule. Bowman's capsule contains porous
capillaries that are permeable to water and small solutes.
Proteins are large molecules, which generally do not filter.
The high concentration of proteins in the blood creates high
osmotic pressure. Osmoregulation in the kidneys maintains
the body's water balance and solute concentration in the
blood
During translation in prokaryotes, the ribosome binds to:
A. the TATA box.
B. the mRNA cap.
C. the terminator sequence.
D. an enhancer sequence.
E. the Shine-Dalgarno sequence. - Correct Answers ✅E. the
Shine-Dalgarno sequence.
, USABO Open Exam Questions and
Answers
Translation is the synthesis of a polypeptide, which occurs
under the direction of mRNA. In prokaryotes, the DNA is not
segregated from ribosomes and the other protein-
synthesizing equipment. Transcription and translation are
coupled, with ribosomes attaching to the leading end of an
mRNA molecule, at the Shine-Dalgarno sequence while
transcription is still in progress. A short stretch of nucleotides
on a prokaryotic mRNA molecule, upstream of the
translational start site that serves to bind to ribosomal RNA,
bring the ribosome to the initiation codon on the mRNA.
The quaternary structure of a protein is determined by:
A. interactions between distant amino acids of the same
polypeptide.
B. interactions between close amino acids of the same
polypeptide.
C. interactions between amino acids of different polypeptide
chains.
D. the arrangement of the alpha helices and beta sheets in
the protein.
E. binding of a coenzyme or cofactor to the protein. - Correct
Answers ✅C. interactions between amino acids of different
polypeptide chains.
Answers
Assume a person is placed on cortisol medication, a
glucocorticoid. How would you expect the rates of ACTH and
CRF hormone production to change in the person?
A. ACTH production would increase, CRF production would
increase
B. ACTH production would increase, CRF production would
decrease
C. ACTH production would decrease, CRF production would
decrease
D. ACTH production would decrease, CRF production would
increase
E. ACTH and CRF production would not change - Correct
Answers ✅D. ACTH production would decrease, CRF
production would increase
The adrenal cortex reacts to stress and responds to endocrine
signals. Stressful stimuli cause the hypothalamus to secrete a
releasing hormone that stimulates the anterior pituitary to
release the tropic hormone ACTH. When ACTH reaches its
target via the bloodstream, it stimulates cells of the adrenal
cortex to synthesize and secrete a family of steroids called
corticosteriods [There are two main types in humans:
glucocorticoids, such as cortisol and the mineralocorticoids,
such as aldosterone]. The elevated levels of corticosteriods in
the blood suppress the secretion of ACTH. The production of
ACTH therefore decreases and CRF, corticoptropin-releasing
factor/hormone, increases.
,USABO Open Exam Questions and
Answers
Carbon particles were injected into the blood of mice. In
which of the following places would you most likely find the
particles?
A. In the glomerular filtrate
B. In the adipose tissue of the liver
C. In monocytes of the spleen
D. In plasma cells of the bone marrow
E. In the loops of Henle - Correct Answers ✅C. In
monocytes of the spleen
Monocytes constitute 5% of leukocytes, which are part of a
phagocytic defense (ingestion of invading organisms by white
blood cells). New monocytes circulate in the blood for only a
few hours and then migrate into tissues, developing into
large macrophages. Organs of the lymphatic system that trap
"foreign" molecules and particles are the spleen, lymph
nodes, adenoid, tonsil, appendix and Peyer's patch, which is
located in the small intestine.
Kidneys provide osmoregulation for the body. Consumption of
which nutrient creates the greatest need for osmoregulation?
A. Cellulose
B. Fat
,USABO Open Exam Questions and
Answers
C. Oil
D. Protein
E. Starch - Correct Answers ✅D. Protein
Osmoregulation is the control of water balance in organisms
living in hypertonic, hypotonic, or terrestrial environments.
Osmoregulation also holds the concentration of solutes in the
blood (and indirectly, the concentration in tissues) at
appropriate levels. The kidney has two distinct regions, the
outer renal cortex and the inner renal medulla, which are
packed with nephrons. Nephrons consist of the glomerulus
and Bowman's capsule. Bowman's capsule contains porous
capillaries that are permeable to water and small solutes.
Proteins are large molecules, which generally do not filter.
The high concentration of proteins in the blood creates high
osmotic pressure. Osmoregulation in the kidneys maintains
the body's water balance and solute concentration in the
blood
During translation in prokaryotes, the ribosome binds to:
A. the TATA box.
B. the mRNA cap.
C. the terminator sequence.
D. an enhancer sequence.
E. the Shine-Dalgarno sequence. - Correct Answers ✅E. the
Shine-Dalgarno sequence.
, USABO Open Exam Questions and
Answers
Translation is the synthesis of a polypeptide, which occurs
under the direction of mRNA. In prokaryotes, the DNA is not
segregated from ribosomes and the other protein-
synthesizing equipment. Transcription and translation are
coupled, with ribosomes attaching to the leading end of an
mRNA molecule, at the Shine-Dalgarno sequence while
transcription is still in progress. A short stretch of nucleotides
on a prokaryotic mRNA molecule, upstream of the
translational start site that serves to bind to ribosomal RNA,
bring the ribosome to the initiation codon on the mRNA.
The quaternary structure of a protein is determined by:
A. interactions between distant amino acids of the same
polypeptide.
B. interactions between close amino acids of the same
polypeptide.
C. interactions between amino acids of different polypeptide
chains.
D. the arrangement of the alpha helices and beta sheets in
the protein.
E. binding of a coenzyme or cofactor to the protein. - Correct
Answers ✅C. interactions between amino acids of different
polypeptide chains.
