Medical Physiology Special/Supplementary Exam — January 2...

40 clinical MCQs in Physiology. Complete Marked out of 1.00 Flag question Which of the following events does not occur dur. Kenya, Africa and global rev...

Questions, Answers & Explanations

1. Q1. Complete Marked out of 1.00 Flag question Which of the following events does not occur during the process of mitosis? Select one:

   • Separation of the chromatids into two sets of 46 "daughter" chromosomes
   • Fragmentation of the nuclear envelope
   • Alignment of the chromatids along the equatorial plate
   • Replication of the genome
   • Condensation of the chromosomes

   Answer: Separation of the chromatids into two sets of 46 "daughter" chromosomes

2. Q2. Complete Marked out of 1.00 Flag question As you are recording the activity of a neuron, you observe multiple EPSPs and IPSPs of various sizes mixed together. This is an example of: Select one:

   • probably only algebraic summation.
   • none of the above
   • probably spatial summation only.
   • probably both spatial and temporal summation.
   • probably temporal summation only.

   Answer: probably only algebraic summation.

3. Q3. Complete Marked out of 1.00 Flag question A neuron cannot produce an action potential: Select one:

   • during the relative refractory period.
   • when the voltage-dependent potassium channels are closed.
   • both b and d.
   • during the absolute refractory period.
   • when there is an inhibitory postsynaptic potential.

   Answer: during the relative refractory period.

4. Q4. Complete Marked out of 1.00 Flag question Immediately after an action potential is propagated, which one of the following ions rapidly diffuses out of the cell into the tissue fluid: Select one:

   • chloride
   • potassium
   • sodium
   • calcium
   • magnesium

   Answer: chloride

5. Q5. Complete Marked out of 1.00 Flag question Which component of transcribed RNA in eukaryotes is present in the initial transcript but is removed before translation occurs: Select one:

   • codons coding for the protein to be produced
   • Ribosome binding site
   • 5' cap
   • 3' Poly A tail
   • Intron

   Answer: codons coding for the protein to be produced

6. Q6. Complete Marked out of 1.00 Flag question In open-loop control mechanisms; Select one:

   • Sensors are essential
   • They are utilised in vital situations
   • The controlled variable is not measured
   • Fluctuations are present
   • They are utilised in transient situations

   Answer: Sensors are essential

7. Q7. Complete Marked out of 1.00 Flag question The diameter of most animal cells ranges from Select one:

   • 10 to 100 µm.
   • 100 to 1000 µm.
   • 1.0 to 10 µm.
   • 0.01 to 0.1 µm.
   • 0.1 to 1.0 µm.

   Answer: 10 to 100 µm.

8. Q8. Complete Marked out of 1.00 Flag question White matter refers to myelinated fibers in the: Select one:

   • both ANS and SNS
   • ANS
   • CNS
   • SNS
   • PNS

   Answer: both ANS and SNS

9. Q9. Complete Marked out of 1.00 Flag question The term central nervous system refers to the: Select one:

   • brain and cranial nerves
   • autonomic and peripheral nervous systems
   • brain, spinal cord, and cranial nerves
   • brain and spinal cord
   • spinal cord and spinal nerves

   Answer: brain and cranial nerves

10. Q10. Complete Marked out of 1.00 Flag question Which one of the following is not a criterion for small neurotransmitter (NT) status? Select one:

    • predictable pharmacological action.
    • evidence of presynaptic release.
    • postsynaptic receptor sites.
    • none of the above.
    • isolation of neurotransmitter substance from presynaptic terminal.

    Answer: predictable pharmacological action.

11. Q11. Complete Marked out of 1.00 Flag question A receptor potential Select one:

    • is an all-or-none phenomenon.
    • always leads to an action potential.
    • increases in amplitude as a more intense stimulus is applied.
    • all of the above .
    • is unchanged when a given stimulus is applied repeatedly over time.

    Answer: is an all-or-none phenomenon.

12. Q12. Complete Marked out of 1.00 Flag question Which is not an example of transmembrane transport between different subcellular compartments? Select one:

    • Transport from the endoplasmic reticulum into the Golgi complex
    • Transport from the cytoplasm into the lumen of the endoplasmic reticulum
    • Transport from the nucleus to the lumen of the endoplasmic reticulum lumen
    • Transport from mitochondrial intermembrane space into the mitochondrial matrix
    • Transport from the golgi complex into the lysosome

    Answer: Transport from the endoplasmic reticulum into the Golgi complex

13. Q13. Complete Marked out of 1.00 Flag question In comparing two types of cells from the same person, the variation in the proteins expressed by each cell type reflects Select one:

    • cell-specific expression and repression of specific genes
    • differences in the DNA contained in the nucleus of each cell
    • differences in the number of chromosomes in each cell
    • differences in the numbers of specific genes in their genomes
    • the age of the cells

    Answer: cell-specific expression and repression of specific genes

14. Q14. Complete Marked out of 1.00 Flag question In the lengthening reaction: Select one:

    • None of the above
    • there is a lengthening of the muscle and tendon in response to supra spinal inhibition of gamma motor neurons.
    • Golgi tendon receptors stimulate the tendon in response to supra spinal inhibition of gamma motor neurons.
    • The contracting muscle suddenly relaxes through inhibition of alpha motor neurons.
    • The muscle is contracted further as the tendon is elongated.

    Answer: None of the above

15. Q15. Complete Marked out of 1.00 Flag question Small transmitter molecules are: Select one:

    • made in the soma, packaged in small synaptic vesicles and transported down axons.
    • packaged in large synaptic vesicles.
    • Soluble gases that freely cross lipid membranes.
    • packaged in small synaptic vesicles.
    • neuropeptides that are synthesized in synaptic terminals.

    Answer: made in the soma, packaged in small synaptic vesicles and transported down axons.

16. Q16. Complete Marked out of 1.00 Flag question Nitric oxide (NO) is a gas neurotransmitter that Select one:

    • is synthesized in the nucleus.
    • does not cross lipid membranes.
    • dilates blood vessels.
    • is transported to the synaptic terminals via microtubules.
    • is stored in synaptic vesicles.

    Answer: is synthesized in the nucleus.

17. Q17. Complete Marked out of 1.00 Flag question Which neurotransmitter is found in motor neurons and is responsible for producing muscle contraction through its release at the neuromuscular junction? Select one:

    • adenosine.
    • acetylcholine.
    • glutamate.
    • dopamine.
    • serotonin.

    Answer: adenosine.

18. Q18. Complete Marked out of 1.00 Flag question 5. The neuron processes that normally receives incoming stimuli are called: Select one

    • dopamin
    • serotonin.

    Answer: dopamin

19. Q19. Complete Marked out of 1.00 Flag question The neuron processes that normally receives incoming stimuli are called: Select one:

    • satellite cells
    • axons
    • Schwann cells
    • dendrites
    • neurolemmas

    Answer: satellite cells

20. Q20. Complete Marked out of 1.00 Flag question 16. The substance that is released at axonal endings to propagate a nervous impulse is called

    • Schwann cells
    • dendrites
    • neurolemmas

    Answer: Schwann cells

21. Q21. Complete Marked out of 1.00 Flag question The substance that is released at axonal endings to propagate a nervous impulse is called: Select one:

    • a neurotransmitter
    • an ion
    • the sodium-potassium pump
    • nerve glue
    • an action potential

    Answer: a neurotransmitter

22. Q22. Complete Marked out of 1.00 Flag question EPSPs Select one:

    • result from release of GABA from presynaptic neurone.
    • result from increase permeability of the postsynaptic membrane to k+
    • can be summated
    • Obey the all or none rule.
    • Have a constant amplitude

    Answer: result from release of GABA from presynaptic neurone.

23. Q23. Complete Marked out of 1.00 Flag question Which of the following is the most likely immediate affect of G-protein activation? Select one:

    • GTP is depleted from the cell.
    • Enzymes are activated that catalyze second messenger formation.
    • Receptors are stimulated to bind to their ligands.
    • G-proteins bind to DNA and activate gene expression.
    • Breakdown of cyclic AMP

    Answer: GTP is depleted from the cell.

24. Q24. Complete Marked out of 1.00 Flag question What determines the effect of neurotransmitter release on the post- synaptic neurons? Select one:

    • the size of the synaptic vesicles.
    • the post-synaptic receptors.
    • the size of the action potential.
    • the neurotransmitter contained in the synaptic vesicles.
    • the concentration of calcium ions reached in presynaptic terminals.

    Answer: the size of the synaptic vesicles.

25. Q25. Complete Marked out of 1.00 Flag question Some cells secrete chemicals into the extracellular fluid that act on cells in the same tissue. Which of the following refers to this type of regulation? Select one:

    • Neuroendocrine
    • Neural
    • Paracrine
    • Endocrine
    • Autocrine

    Answer: Neuroendocrine

26. Q26. Complete Marked out of 1.00 Flag question Which cell organelle is involved in necrosis? Select one:

    • nucleus
    • Lysosome
    • Golgi
    • Mitochondria

    Answer: nucleus

27. Q27. Complete Marked out of 1.00 Flag question Redundancy or "degeneration" of the genetic code occurs during which of the following steps of protein synthesis? Select one:

    • Transcription
    • Protein glycosylation
    • Translation
    • Post-transcriptional modification
    • DNA replication

    Answer: Transcription

28. Q28. Complete Marked out of 1.00 Flag question The function of which of the following organs or systems is dominated by the sympathetic nervous system? Select one:

    • Salivary glands
    • Systemic blood vessels
    • Gastrointestinal motility
    • Heart
    • Gastrointestinal gland secretion

    Answer: Salivary glands

29. Q29. Complete Marked out of 1.00 Flag question Which of the following is not characteristic of a reflex action? Select one:

    • Frequently occurs without conscious perception
    • Modification by impulses from various parts of the central nervous system
    • May involve simultaneous contraction of some muscles and relaxation of others
    • May involve ether somatic or visceral responses but never both simultaneously.
    • Always involves transmission across at least one synapse

    Answer: Frequently occurs without conscious perception

30. Q30. Complete Marked out of 1.00 Flag question Which of the following decreases in length during the contraction of a skeletal muscle fiber? Select one:

    • Thin filaments
    • Thick filaments
    • A band of the sarcomere
    • I band of the sarcomere
    • Z discs of the sarcomere

    Answer: Thin filaments

31. Q31. Complete Marked out of 1.00 Flag question Lysosomes can be expected to be present in large numbers in cells which Select one:

    • carry out phagocytosis
    • replicate DNA
    • are actively dividing
    • are migrating
    • secrete peptide hormones

    Answer: carry out phagocytosis

32. Q32. Complete Marked out of 1.00 Flag question Tetonic contraction of a skeletal muscle fiber results from a cumulative increase in the intracellular concentration of which of the following? Select one:

    • Troponin
    • Ca++
    • ATP
    • Na+

    Answer: Troponin

33. Q33. Complete Marked out of 1.00 Flag question Which of the following is a consequence of myelination in large nerve fibers? Which of the following is a consequence of myelination in large nerve fibers? Select one:

    • Dynamic gamma motor neurons
    • Type Ia inhibitory interneurons
    • Alpha motor neurons
    • Type II excitatory interneurons
    • Type Ib inhibitory interneurons

    Answer: Dynamic gamma motor neurons

34. Q34. Complete Marked out of 1.00 Flag question At the very start of exercise Select one:

    • The heart rate falls due to vaso-vagal stimulation
    • There is no change in respiratory or heart rate
    • The respiratory rate rises as a feed forward response
    • The heart rate rises due to a hormonal response
    • The respiratory rate falls as a feed forward response

    Answer: The heart rate falls due to vaso-vagal stimulation

35. Q35. Complete Marked out of 1.00 Flag question The appearance of which of the following distinguishes eukaryotic cells from lower units of life? Select one:

    • Protein
    • Nucleus
    • Membranes
    • DNA
    • RNA

    Answer: Protein

36. Q36. Complete Marked out of 1.00 Flag question Which channel membrane protein is specifically important in the process of neurotransmitter release? Select one:

    • neurotransmitter receptor sodium channels.
    • voltage-dependent (gated) potassium channels.
    • voltage-dependent (gated) chloride channels.
    • voltage-dependent (gated) calcium channels.
    • neurotransmitter receptor potassium channels.

    Answer: neurotransmitter receptor sodium channels.

37. Q37. Complete Marked out of 1.00 Flag question Which of the following statements about the contraction of skeletal muscle is correct? Select one:

    • The power stroke of skeletal muscle contraction occurs when the myosin head binds ATP.
    • The power stroke does not require ATP
    • The power stroke of skeletal muscle contraction occurs when the myosin head hydrolyses ATP.
    • The power stroke of skeletal muscle contraction occurs when the myosin head releases ADP and Pi.
    • The power stroke of skeletal muscle contraction occurs when the myosin head releases ATP.

    Answer: The power stroke of skeletal muscle contraction occurs when the myosin head binds ATP.

38. Q38. Complete Marked out of 1.00 Flag question How are neurotransmitters released into a synapse in response to an action potential? Select one:

    • None of the above
    • They pass through voltage-gated neurotransmitter channels.
    • They pass through gap junctions into the post-synaptic cell.
    • They diffuse through the cell when the action potential reverses membrane potential.
    • They are released by membrane fusion of vesicles in response to increased calcium concentration.

    Answer: None of the above

39. Q39. Complete Marked out of 1.00 Flag question The process whereby the content of synaptic vesicles is released into the synaptic cleft/gap is called: Select one:

    • none of the above
    • pinocytosis.
    • phagocytosis.
    • endocytosis.
    • exocytosis.

    Answer: none of the above

40. Q40. Complete Marked out of 1.00 Flag question The sweat glands and piloerector muscles of hairy skin are innervated by which of the following fiber types? Select one:

    • Cholinergic postganglionic parasympathetic fibers
    • Cholinergic postganglionic sympathetic fibers
    • Adrenergic preganglionic parasympathetic fibers
    • Adrenergic preganglionic sympathetic fibers
    • Adrenergic postganglionic sympathetic fibers

    Answer: Cholinergic postganglionic parasympathetic fibers