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Question 1
Correct
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In RFLP, the DNA fragments are separated by length through a process known as:
Your Answer: Inversion
Explanation:Samples of DNA from individuals are broken into pieces by restriction enzymes and the fragments are separated according to their lengths via gel electrophoresis. Although now largely obsolete due to the rise of inexpensive DNA sequencing technologies, RFLP analysis was the first DNA profiling technique inexpensive enough to see widespread application.
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This question is part of the following fields:
- Genetics
- Physiology
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Question 2
Correct
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Question 3
Correct
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A 36 year old opera singer is admitted for a right thyroid lobectomy. Post operatively, he is unable to sing high notes. Which muscle is likely to demonstrate impaired function?
Your Answer: Cricothyroid
Explanation:Thyroidectomy has been reported as the most frequent cause of external branch of superior laryngeal nerve (EBSLN) injury. Diagnosis of EBSLN injury may be difficult because the symptoms are nonspecific in many cases. However, advanced diagnostic techniques have revealed the incidence to be relatively high, ranging from 5 to 28%. Paralysis of the EBSLN causes difficulty with high pitch phonation and decreased pitch range secondary to failure of cricothyroid muscle stimulation and lack of tension in the vocal cord. This symptom may be extremely serious for professional voice users. EBSLN injury can also cause vocal fatigue, hoarseness, breathy sounding voice, and vocal nodules.
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This question is part of the following fields:
- Head & Neck
- Pathology
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Question 4
Correct
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In meiosis, the period of prophase 1 involves:
Your Answer: Replicated DNA condensing to form visible chromosomes
Explanation:Prophase 1 has been divided into five different stages (laptotene, zygotene, pachytene, diplotene and diakinesis). In prophase 1, chromosomes are going to condense to become visible, each chromosome will contain two chromatids that are joined at the centromere.
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This question is part of the following fields:
- Genetics
- Physiology
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Question 5
Correct
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The initial rapid depolarization in the action potential of cardiac muscle cells is due to:
Your Answer: Opening of voltage-gated Na+ channels
Explanation:The initial depolarization of the action potential in a cardiac muscle cell is due to the sodium current generated by opening of the voltage gated sodium channels leading to an influx of sodium ions into the cell and raising the membrane potential towards threshold.
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 6
Correct
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A man suffers damage to his vagus nerve during surgery on his neck. The vagus nerve is cut near its exit from the skull. The man loses his parasympathetic tone raising his heart rate and blood pressure. What other feature will be likely present with a vagus nerve injury?
Your Answer: Hoarse voice
Explanation:The vagus nerve is a mixed nerve with both autonomic and somatic effects. Its most important somatic effect is the motor supply to the larynx via recurrent laryngeal nerves. If one vagus nerve is damaged, the result will be the same as damage to a single recurrent laryngeal nerve, leading to hoarseness of voice. The vagus exits the skull via the jugular foramen, accompanied by the accessory nerve. Anal tone, erections, and urination are all controlled by the sacral parasympathetic and would not be affected by the loss of the vagus. Parasympathetic controlled pupillary constriction is via the oculomotor nerve and would not be affected by the loss of the vagus.
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This question is part of the following fields:
- Anatomy
- Head & Neck
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Question 7
Correct
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Closure of the tricuspid valve is marked by which of the following features of the jugular venous waveform?
Your Answer: c wave
Explanation:The jugular venous pressure (JVP) classically has three upward deflections and two downward deflections. The upward deflections are the a (atrial contraction), c (ventricular contraction and resulting bulging of tricuspid into the right atrium during isovolumetric systole) and v = venous filling. The downward deflections of the wave are the x (the atrium relaxes and the tricuspid valve moves downward) and the y descent (filling of ventricle after tricuspid opening).
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This question is part of the following fields:
- Cardiovascular
- Physiology
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Question 8
Incorrect
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Which of the following muscles is least likely to be involved in forceful expiration:
Your Answer: Internal intercostal muscles
Correct Answer: External intercostal muscles
Explanation:Forceful expiration is primarily produced by the deeper thoracic muscles (internal and innermost intercostal muscles, subcostals and transversus thoracis) aided by contraction of the abdominal wall muscles which increase intra-abdominal pressure thus further reducing the volume of the thorax.
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This question is part of the following fields:
- Anatomy
- Thorax
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Question 9
Correct
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Regarding bronchial innervation which of the following is correct:
Your Answer: Alpha 1 receptors increase bronchial constriction
Explanation:Stimulation of β2 receptors results in smooth muscle relaxation and bronchodilation. α1 receptors cause smooth muscle contraction in the bronchioles although minor to the β2 effects.
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This question is part of the following fields:
- Physiology
- Respiratory
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Question 10
Correct
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Regarding integrins, which option is false?:
Your Answer: Play no role in cell signalling.
Explanation:Integrins are transmembrane receptors that facilitate cell-extracellular matrix (ECM) adhesion. Upon ligand binding, integrins activate signal transduction pathways that mediate cellular signals such as regulation of the cell cycle, organization of the intracellular cytoskeleton, and movement of new receptors to the cell membrane. Integrins are obligate heterodimers, meaning that they have two subunits: α (alpha) and β (beta). Integrins play an important role in cell signalling by modulating the cell signalling pathways of transmembrane protein kinases such as receptor tyrosine kinases (RTK).
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This question is part of the following fields:
- Cell Biology
- Physiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
