Q- Which of the following statements correctly describes the volume of distribution of a drug?
A- It is a kinetic parameter that correlates dose with plasma level of a drug at zero time
B- It is the capacity of a drug to attach to plasma protein
C- It is the concentration of the drug in plasma at a certain time
D- It is the rate of diffusion of the drug through the intracellular component
A- It is a kinetic parameter that correlates dose with plasma level of a drug at zero time. Volume of distribution (Vd) is a theoretical value that relates the amount of drug given to the concentration in plasma at time zero. It does not describe protein binding, plasma concentration at a later time, or diffusion rate.
Q- Deficiency of which of the following enzymes is associated with von Gierke’s disease?
A- α-1,4-phosphorylase
B- Glucose-6-phosphatase
C- Hexosaminidase A
D- Phosphofructokinase-1
B- Glucose-6-phosphatase- Von Gierke’s disease (Glycogen storage disease type I) is caused by a deficiency of glucose-6-phosphatase, leading to severe fasting hypoglycemia and glycogen accumulation in the liver and kidneys.
Q- Which of the following differentiates HIV virus from RNA tumor viruses?
A- HIV contains 2 copies of RNA
B- HIV contains the pol gene
C- HIV has a cytolytic activity
D- HIV is a retrovirus
C- HIV virus has a cytolytic activity- HIV is cytolytic, meaning it directly destroys the host CD4⁺ T-cells it infects. This feature distinguishes HIV from RNA tumor viruses, which do not typically cause direct lysis of their host cells. The other statements are not unique to HIV: HIV contains two copies of RNA — so do other retroviruses. HIV contains the pol gene — all retroviruses do. HIV is a retrovirus — RNA tumor viruses are also retroviruses.
