1] A healthy man is flying in a plane that has been pressurized to 10,000 feet (523 HG) . Which of the following statements regarding effects of this barometric pressure is true ?

1. It will cause a modest reduction in arterial Po2 .
2. It will not affect alveolar Po2 because inspired O2 remains at 0.21
3. Will be associated with significant desaturation of arterial Hemoglobin
4. None of the above

Ans: A

2] Of the following cell types, which would contain many mitochondria in the apical portion of the cell?

1. Smooth muscle cells
2. Ciliated epithelium cells
3. Steroid secreting cell
4. Skeletal muscle cells

Ans : B

3] Which of the following statements most accurately describes features of neuromuscular transmission?

1. Each muscle fiber contains multiple axon terminals
2. The end plate is highly enriched in electrically excitable gates
3. Enzymatic degradation of the transmitter can terminate transmission
4. Acetyl choline causes chloride channels to open as a result of membrane depolarization

Ans : C

4] Which of the following statements regarding expiration is correct ?

1. At lung volumes close to vital capacity [VC] ,expiratory air flow is independent of expiratory effect.
2. at lung volumes close to VC ,airway resistance is at its peak
3. At lung volumes close to VC , expiratory air  flow increases with pleural pressures.
4. None of the above

Ans : C

5] RNA processing can be best described by which of the following statements?

1. It occurs in the cytoplasm
2. It includes the methylation of nucleotides in RNA 
3. It results in the formation of new covalent bonds between RNA & DNA
4. It includes the addition of a tail of polyadenylic acid at the 5'end

Ans : B

6] The upstroke of ventricular action potential is primarily due to which one of the following actions?

1. An inward flux of Ca2.
2. An inward K + current
3. An outward K+ current
4. An inward Na + Current

Ans : D

7] Which of the statements about acetyl choline release & deactivation is true?

1. ACH release is blocked by toxin associated with Clostridium tetanae
2. Uptake of Ach into the presynaptic receptor is the most important mechanism in terminating the Ach signal
3. Inhibitors of the enzyme MAO are important in the treatment of depression because they inhibit the breakdown of ach into its constituents .
4. The influx of Ca2+ into the depolarized axon terminal is a prerequisite for the release of stored Ach

Ans : D

8] All the following thalamic nuclei are connected to the basal ganglia except

1. Ventrolateral
2. medial central
3. Pulvinar
4. Ventro anterior

Ans : C

9] All the statements concerning mammalian chromosomes are true except :

1. DNase 1 can be used to treat chromosomes to determine inactive regions of DNA.
2. Approximately 7% of the sequences contained in the eukaryotic genome are copied into RNA.
3. Heterochromatin is a term used for inactive DNA & euchromatin is a term used for these regions of the DNA that are transcriptionally active . 
4. Both C & D are false.

Ans : A

10] Each statement below concerning the contraction of myofibrils in skeletal muscle is true except :

1. The size of A band decreases
2. The size of H band decreases
3. The size of I band decreases
4. Thin filaments penetrate the A band

Ans : A

11] All the following statements concerning hormonal control of menstrual cycle are true except :

1.  Estradiol causes a proliferation & thickening in the endometrial lining
2. Progesterone induces differentiation of the endometrial lining into a secretory phase
3. LH stimulates thecal cells to produce androgens that are aromatized to estrogen by the granulosa cells
4. The LH surge immediately precedes endometrial shedding & menses

Ans : D