2013 Test 1 Questions Flashcards
Caffeine:
A. has a structure similar to ribose sugars
B. is transported through the same channel as adenosine, thereby blocking adenosine from entering cells
C. inhibits the normal depressant action of the nucleoside adenosine
D. is activated to become a signaling molecule by a cyclase
E. has a pyrimidine-like structure similar to adenosine
C.
Sweet receptors on the tongue:
A. Specifically recognize only sugar molecules
B. trigger a signal cascade that ends with the phosphorylation of the sweet moleules
C. may recognize certain molecules that are not sugar molecules
D. trigger a signal cascade that ends with the release of acid from the cell
E. trigger a signal cascade that ends with the release of negatively charged ions in the cytosol.
C.
The major mineral component of teeth is: A. keratin B. mucopolysaccharide C. periodontum D. pulp E. hydroxyapatite
E
Some part of teeth:
A. are composed of living cells and are therefore capable of extensive repair.
B. contain nuclear processes of cells known as xerostomia
C. have a harness such that they are impermeable to any type of chemical
D. have channels specific for sodium that are important to mineralization and demineralization of enamel, dentin and cementum
E. are decayed by the action of sucrase
A.
A hormone that involves sensing of stress by the brain, setting off of a cascade of signaling compounds formed in turn by hypothalamus, anterior pituitary, and adrenal cortex is: A. cortisol B. ghrelin C. somatostatin D. insulin E. glucagon
A
Skeletal muscles may utilize which of the following as a source of energy for contractile work such as running? A. Steroid hormones B. cholesterol C. fatty acids D. GTP E. AMP
C
In addition to their carbon skeleton, amino acids have nitrogen-containing amino groups that
A. are sequestered by pancreatic enzyme secretion such that toxic ammonia does not accumulate in circulation
B. are handled by an enzymatic pathway partly located in lysosomes, partly located in cytosol
C. are handled by the urea cycle primarily in the liver
D. are handled by enzymes located solely in lysosomes
E. The kidney reabsorbs from urine such that nitrogen is completely conserved.
C.
In the Hill equation, the Hill coefficient, n, is an expression of cooperativity. If positive cooperativity is expressed, the value of n can range from: A. 1 to x (where x=subunits) B. infinity, and beyond C. 0 to 1 D. 0% to 100% E. log of P50 to log of P100
A
The P50 is:
A. the partial pressure of oxygen in the lungs
B. not meaningful for describing oxygen binding
C. the P02 at which the fractional saturation of oxygen binding sites is 0.5
D. the partial pressure of oxygen at 50 degrees centigrade
E. constant for a molecule such as heme
C
The right shift is caused by 2,3-BPG because:
A. binds to oxyhemoglobin non-specifically
B. interacts with heme irons (Fe2+)
C. slightly increases the temperature of Hb solutions in the red cell
D. binds to deoxyhemoglobin
E. absorbs protons
D
A right shift of the hemoglobin/oxygen binding curve implies that, compared to the unshifted curve, the hemoglobin of the shifted curve:
A. has dissociated into 4 subunits
B. binds more oxygen at saturation
C. will be less saturated near a p02 of 25 torr
D. has a lower P50
E. will be more highly saturated in the lungs
C
Every carboxylase enzyme requires one of two cofactors derived from vitamins. One cofactor is vitamin K, the other is: A. folate B. riboflavin C. thiamin D. biotin E. cobalamin
D
In the committed step of glycolysis, which of the following is neither a reactant nor a product? A. ADP B. ATP C. F6P D. F1,6BP E. G6P
E
