Fluid mosaic model of membrane structure was proposed by:

 # Fluid mosaic model of membrane structure was proposed by:

A. Watson and Crick

B. Edward H. Angle

C. G.V. Black

D. Singer and Nicolson

The correct answer is D. Singer and Nicolson.

The fluid mosaic model explains various observations regarding the structure of functional cell membranes. According to this biological model, there is a lipid bilayer (two molecules thick layer consisting primarily of amphipathic phospholipids) in which protein molecules are embedded. The phospholipid bilayer gives fluidity and elasticity to the membrane. Small amounts of carbohydrates are also found in the cell membrane. The biological model, which was devised by SJ Singer and G. L. Nicolson in 1972, describes the cell membrane as a two-dimensional liquid that restricts the lateral diffusion of membrane components. 

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Which of the following does not occur in mitochondria?

 # Which of the following does not occur in mitochondria?

A. TCA

B. HMP shunt

C. Urea cycle

D. Beta oxidation of fatty acids

The correct answer is B. HMP shunt.

HMP shunt or hexose monophosphate pathway or pentose phosphate pathway (PPP) or phosphogluconate pathway : for oxidation of glucose as an alternative pathway to glycolysis and TCA cycle. Enzymes for HMO shunt are located in cytosol/cytoplasm.

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Muller’s muscle is seen in:

 # Muller’s muscle is seen in:

A. Nose tip

B. Upper eye lid

C. Lower eye lid

D. Mid canthus

The correct answer is B. Upper eyelid.

Posterior to the levator aponeurosis is the underlying Muller's muscle complex- Orbitalis muscle or the circular fibres of the ciliary muscle, both of which are also known as Muller's muscle. 

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Why is morphine contraindicated in maxillofacial injury or head injury?

 # In patients with maxillofacial injury, narcotics like morphine are contraindicated because:

A. Morphine causes miosis

B. Morphine causes mydriasis

C. Morphine is respiratory irritant

D. Morphine is circulatory depressant

The correct answer is A. Morphine causes miosis.

Miosis masks the neurological signs of cerebral hemorrhage.

  Morphine is a phenanthrene derivative opioid analgesic. It is contraindicated in head injuries due to:

- Retention of carbondioxide leading to increased intracranial pressure

- exaggerated depression of respiration and the potential need to control ventillation of the patient must be considered

- vomitting, miosis (miosis will interrupt in monitoring the eye signs in case of probable head injury in the patients of maxillofacial injury), and altered mental state interfere with assessment of prognosis in patients with head injury

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