1 - The LC50 for carbon monoxide alone is 6600 ppm. For a mixture of carbon mono
ID: 986901 • Letter: 1
Question
1 - The LC50 for carbon monoxide alone is 6600 ppm. For a mixture of carbon monoxide and 5% carbon dioxide, the LC50 for CO drops to 3900 ppm. 5% carbon dioxide by itself is not lethal. Which of the following statements is appropriate based on this data?
a)CO2potentiates the effect of CO b)CO2is an antagonist for CO c)CO2exerts a synergistic effect in combination with CO
2 - The specific endocytosis process by which liquids or very small particles are engulfed and transported across the membrane is known as :
a)Phagocytosis b)Pinocytosis c)Exocytosis
3 - At pH 7.4 a weak organic acid with a pKa of 6.4 would be?
a)10% ionized b)40% ionized c)60% ionized d)90% ionized
4 - Which of the following does not occur in a Phase I metabolism of a toxin?
a)Oxidation b)Reduction c)Conjugation d)Hydrolysis
Explanation / Answer
1)
The LC50 for carbon monoxide alone is 6600 ppm. For a mixture of carbon monoxide and 5% carbon dioxide, the LC50 for CO drops to 3900 ppm. 5% carbon dioxide by itself is not lethal. Which of the following statements is appropriate based on this data is
a)CO2 potentiates the effect of CO
2)
The specific endocytosis process by which liquids or very small particles are engulfed and transported across the membrane is known as :Pinocytosis
3) pH 7.4 a weak organic acid
as pH = - log [H+] = pKa = -log Ka
anti (-7.4 ) = [H+] anti (-6.4 ) = Ka
[H+] = 3.98 * 10-8 Ka = 3.98 * 10-7
let organic weak acid be represented by HA
HA -------> H + + A-
let 1 0 0
at equillibrium 1-X X X
the % of ionization=
= 3.98 * 10-7 / 3.98 * 10-8 * 100 = 10 %
correct option is a)10% ionized
4) which does not occur in a Phase I metabolism of a toxin?
correct option is c)Conjugation
as conjugation occur in phase 2 metabolism of a toxin .
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