Question

Microbiology Labs Practice Problems 1. You have 1 ml sample of a patient's serum and you need to make a 1:10 dilutions of it in saline. How much saline you would add to your sample to accomplish that? A. 10 ml B. 9 ml C. 9.9 ml D. 0.9 ml E. 0.99 ml 2. You have 0.5 ml sample of a patient's serum and you need to make a 1:10 dilutions of it in saline. How much saline you would add to your sample to accomplish that? A. 1 ml B. 4 mi C. 4.5 ml D. 4.9 ml E. 4.99 ml 3. You have 0.5 ml of a patient's serum and you need to make a 1:100 dilutions of it in saline. How much saline you would add to your sample to accomplish that? A. 0.5 ml B. 4.5 ml C. 4 ml D. 49 ml E. 49.5 ml 4. You have a vial of Vancomycin with concentration of 1 mg per ml of saline. You need to administer 1 microgram per kilogram of patient's body weight. If the patient weights 50 kilograms, what volume of the drug you need to administer to the patient? A. 10 u B. 20 ul C. 50 ul D. 100 ml E. 1 mi 5. You have vial of Penicillin with concentration of 10 mg per ml. You are asked to administer 2 ml of 1:100 dilution of the drug to your patient. How much of the drug is your patient getting? A. 100 g B. 200 mg C. 500 mg D. 1 mg E. 2 mg

Answer 1

Answer:

1. A. 10 ml

Reason: Ratio = 1:10

Blood sample= 1ml, so saline = 10 ml

2. E. 4.99

Reason: Ratio = 1: 10

Blood sample = 0.5ml

Saline = 4.99 ml (~ 5ml)

3. E. 49.5 ml

Reason: Ratio = 1:100

Blood sample = 0.5ml

Saline = 49.5 ml

4.c. 50 microliter

Reason: Concentration = 1mg /ml = 100 micrograms/ml

Patient weight = 50 kg

Volume to be administered = 1 micrograms ×50 = 50 micrograms

= 50 micrograms in 50 microliter

5. B. 200 micrograms

Reason: concentration = 10 mg / ml

2ml = 20 mg

Dilution ratio = 1:100

= 20÷ 100 = 0.2 mg = 200 micrograms