All Biochemistry Resources
Example Questions
Example Question #1 : Other Hormone Pathways
Which of the following statements about adrenergic receptors is true?
Isoproterenol is a beta-agonist.
Phentolamine is a beta-antagonist.
Propranolol is an alpha-agonist.
Norepinephrine/noradrenaline is the methylated form of epinephrine/adrenaline.
Isoproterenol is a beta-agonist.
Phentolamine is an alpha-antagonist. Propranolol is an beta-agonist. Epinephrine/adrenaline is the methylated form of norepinephrine/noradrenaline.
Example Question #2 : Other Hormone Pathways
Which of the following statements about pancreatic hormones is not true?
Glucagon is secreted in response to high blood glucose levels.
Insulin stimulates muscle and fat cells to store glucose.
Delta cells secrete somatostatin.
Beta cells secrete insulin.
Glucagon is secreted in response to high blood glucose levels.
Insulin is secreted in response to high blood glucose levels, which increases cell uptake of glucose. Glycogen has the opposite effect - it stimulates glycogenolysis and lipolysis to release glucose into the bloodstream during times of fasting/starvation.
Example Question #3 : Other Hormone Pathways
Which of the following does not lead to an increase in the secretion of insulin?
I. Gastric inhibitory polypeptide (GIP)
II. Cholecystokinin (CCK)
III. Closing of the voltage gated potassium channels
IV. Decreased arginine levels
I, II, and IV
I and II
III only
IV only
IV only
Elevated arginine leads to an increase in secretion of insulin, not decreased. GIP, CCK and closing of the voltage gated potassium channels lead to an increase in secretion of insulin.
Example Question #1 : Other Hormone Pathways
During a fasting state, the brain reduces its need for serum glucose by using which of the following substances as an alternate energy source?
Beta-carotene and apoprotein B
Beta-hydroxybutyrate and apoprotein B
Beta-hydroxybutyrate and acetoacetate
Beta-hydroxybutyrate only
Beta-hydroxybutyrate and acetoacetate
Ketone bodies, which include acetoacetate, beta-hydroxybutyrate, and acetone, are produced by the liver in the fasting state by beta-oxidation of fatty acids. They are then released into the blood stream, where they can be used as alternative energy sources for other organs, such as muscle, kidney, and brain. Apoprotein B is one of the proteins that hold lipoproteins together. Beta-carotene is a vitamin with antioxidant properties.
Example Question #2 : Other Hormone Pathways
Which of the following is not a step in the signal transduction pathway when epinephrine acts on its receptor?
Activation of adenylate cyclase
Increase in the quantity of cAMP
Activation of protein kinase A
Activation of diacylglycerol and IP3
Activation of a G protein
Activation of diacylglycerol and IP3
Epinephrine first binds to an adrenergic receptor. The activated receptor works via a G protein, and so GDP is exchanged for GTP and the protein is activated. This then causes activation of adenylate cyclase and subsequent conversion of ATP to cAMP. cAMP acts upon protein kinase A and several other effector molecules. Diacylglycerol and IP3 are second messengers that are uninvolved in this process.
Example Question #3 : Other Hormone Pathways
Erythropoietin is an important glycoprotein in the human body. What is the function of erythropoietin?
Stimulates production of red blood cells
Stimulates secretion in the tubules of the nephron
Stimulates white blood cell activity
Stimulates red blood cell destruction
Stimulates filtering in the kidney
Stimulates production of red blood cells
Erythropoietin is a glycoprotein hormone produced in the kidney that stimulates the production of red blood cells in the bone marrow.
Example Question #4 : Other Hormone Pathways
Which hormone below would result in an increase in cAMP?
Human growth hormone
Epinephrine
None of these
Epidermal growth factor
Insulin
Epinephrine
Epinephrine and glucagon are examples of hormones that affect G protein-coupled receptors like adenylate cyclase and increase levels of cAMP. The other hormones listed affect receptor tyrosine kinases and non-receptor tyrosine kinases.
Example Question #63 : Hormones And Neurotransmitters
Which of the following hormones crosses the plasma membrane in order to affect its target cell?
None of these hormones act by crossing the plasma membrane
Insulin
Glucagon
Epinephrine
Thyroxine
Thyroxine
This question is asking us to identify a hormone that passes through the target cell's plasma membrane in order to affect that cell.
When looking at hormones, there are three general types: amine, peptide, and steroid. Out of these, steroid hormones are all capable of crossing the plasma membrane. In fact, the receptors for steroid hormones are often found in the cytoplasm or nucleus of the target cell. Generally, amine and peptide hormones act by binding to a receptor on the outer surface of the target cell's plasma membrane. However, thyroxine is an exception. Thyroxine is an amine hormone based off of the amino acid tyrosine. Normally, amine-derived hormones do not cross the plasma membrane, but the largely hydrophobic nature of thyroxine allows it to cross the plasma membrane and bind with its intracellular receptor.
Of the other answer choices shown, none of them cross the cell membrane. Epinephrine is an amine-derived hormone, utilizing tyrptophan as the starting material. Insulin, glucagon, and growth hormones are all peptide hormones.
Example Question #5 : Other Hormone Pathways
Which of the following is a polypeptide?
Glucagon
Epinephrine
Pyridoxal phosphate
Biotin
Glucagon
Glucagon is a short peptide hormone involved in triggering signal cascades in response to low blood glucose. Biotin, also known as vitamin B7, is a cofactor in fatty acid synthesis. Pyridoxal phosphate, the activated form of vitamin B6, is a cofactor in transamination reactions, among others. Epinephrine is a steroid hormone involved in the fight or flight response.
All Biochemistry Resources
![Learning Tools by Varsity Tutors](https://vt-vtwa-app-assets.varsitytutors.com/assets/problems/og_image_practice_problems-9cd7cd1b01009043c4576617bc620d0d5f9d58294f59b6d6556fd8365f7440cf.jpg)