A fresh set of 20 random questions is generated every time you open this page and every time you refresh it.For each of the following multiple choice questions, choose the most appropriate answer :
1. Which of the following acts as an ATPase during the contraction cycle of muscle?
A. actin molecules
B. troponin molecules
C. tropomyosin molecules
D. myosin cross-bridges
2. In motor neurons, the portion of the cell with the lowest threshold for the production of a full- fledged action potential is:
A. initial segment
B. soma
C. dendritic zone
D. node of Ranvier
3. Which of the following mechanisms is currently implicated in learning and memory?
A. Modulation of release of neurotransmitters in postsynaptic neurons in response to repeated firing of presynaptic neurons
B. Modulation of neurotransmitter receptor synthesis in postsynaptic neurons
C. Formation of new neurons
D. All these
4. Which of the following transport processes is mediated by a carrier protein in the plasma membrane?
A. Glucose uptake through SGLT-1
B. Na influx through Na channels
C. Potassium influx through K channels
D. Water fluxes through aquaporins
5. The release of androgens from the adrenal cortex is stimulated mainly by:
A. LH
B. FSH
C. ACTH
D. GnRH
6. From a physiologic standpoint, the advantage of a 'parietal cell vagotomy' over truncal vagotomy for treating duodenal ulcer is that in parietal cell vagotomy:
A. a gastrojejunostomy is not required
B. only basal acid output is reduced
C. G cells are also denervated
D. pyloric sphincter is also denervated
7. Which of the following modes of transport across the cell membrane is quantitatively more important for flux of ions?
A. Diffusion
B. Filtration
C. Vesicular transport
D. None of these
8. Neurons mediating direct inhibition in the spinal cord usually secrete:
A. glycine
B. substance P
C. glutamate
D. All these
9. In postnatal life, thyroid hormones do notincrease oxygen consumption in the:
A. heart
B. skeletal muscle
C. adult brain
D. liver
10. Most pancreatic zymogens are activated in the duodenal lumen by:
A. enterokinase (enteropeptidase)
B. trypsin
C. trypsin activator protein
D. All these
11. Thin filaments at either end of the sarcomere are attached to the
A. Z line.
B. M line.
C. H band.
D. A band.
12. Rhodopsin has peak sensitivity to light at a wavelength of:
A. 405 nm
B. 505 nm
C. 605 nm
D. 705 nm
13. Physiologically, an intact innervated muscle can normally be made to contract by stimulation of which of the following neurons innervating that muscle?
A. ?-motor neurons
B. ?-motor neurons
C. ?-motor neurons
D. Either A or C
14. The hypertensive form of congenital adrenal hyperplasia is due to a deficiency of:
A. 11ß hydroxylase
B. 21 hydroxylase
C. 3ß-hydroxysteroid dehydrogenase
D. DHEA sulfokinase
15. Which of the following mechanisms allows complete absorption of glucose from the intestinal lumen into the cytosol of the enterocyte?
A. Simple diffusion through GLUT-5
B. Na-glucose cotransporter-1 (SGLT-1)
C. Na channels in enterocyte membrane
D. Paracellular uptake via gap junctions
16. Which of the following hormones is not detectable in normal females?
A. Androstenedione
B. Testosterone
C. Dehydroepiandrosterone sulfate
D. None of these
17. Hormones produced by the ovary include:
A. Estrogens
B. Progesterone
C. Relaxin
D. All these
18. Which of the following is not a feature of corticospinal tract disease?
A. Cogwheel rigidity
B. Spasticity
C. Plantar extensor response
D. Exaggerated deep tendon reflexes
19. The Jendrassik's maneuver facilitates stretch reflexes by:
A. exciting alpha motor neurons
B. increasing gamma efferent discharge
C. releasing glycine
D. All these
20. Congenital lipoid adrenal hyperplasia occurs due to a lack of:
A. CYP450 scc (desmolase)
B. 3ß-hydroxysteroid dehydrogenase
C. 17a hydroxylase
D. steroidogenic acute regulatory protein
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