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

Answer 1

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⁺] = pK_a = -log K_a

anti (-7.4 ) =  [H⁺] anti (-6.4 ) = K_a

[H⁺] = 3.98 * 10^-8   K_a = 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 .