ALAT Formulas and Calculations — Questions and Answers
Question 1: An animal room is maintained at 68°F. What is this temperature in Celsius?
- 18°C
- 20°C (Correct answer)
- 24°C
- 30°C
Correct answer: 20°C
The formula is °C = (°F − 32) × 5/9. So (68 − 32) × 5/9 = 36 × 5/9 = 20°C. The recommended temperature range for most laboratory rodents is 18–26°C (64–79°F).
Question 2: You need to make 100 mL of a 1:10 dilution of a disinfectant in water. How many mL of disinfectant do you use?
- 1 mL
- 5 mL
- 10 mL (Correct answer)
- 50 mL
Correct answer: 10 mL
A 1:10 dilution means 1 part concentrate per 10 parts total solution. For 100 mL total: 100 ÷ 10 = 10 mL of disinfectant, then add 90 mL of water to reach 100 mL.
Question 3: A mouse weighs 25 grams and requires a drug at 10 mg/kg. What dose in mg should the mouse receive?
- 0.025 mg
- 0.25 mg (Correct answer)
- 2.5 mg
- 25 mg
Correct answer: 0.25 mg
First convert grams to kilograms: 25 g = 0.025 kg. Then: 0.025 kg × 10 mg/kg = 0.25 mg. Accurate weight-based dosing is critical for both animal welfare and experimental validity.
Question 4: You need 1 liter of a 2% disinfectant solution. Your stock is 20% concentration. How many mL of stock do you need?
- 10 mL
- 20 mL
- 100 mL (Correct answer)
- 200 mL
Correct answer: 100 mL
Using the dilution formula C1V1 = C2V2: (20%) × V1 = (2%) × 1000 mL, so V1 = 2000 / 20 = 100 mL of stock. Add water to bring the total volume to 1000 mL.
Question 5: A room thermometer reads 30°C. The acceptable range for the species housed is 64–79°F. Is this within range?
- Yes — 30°C equals 72°F, which is within range
- No — 30°C equals 86°F, which is too warm (Correct answer)
- Yes — 30°C equals 79°F, which is at the upper limit
- No — 30°C equals 60°F, which is too cool
Correct answer: No — 30°C equals 86°F, which is too warm
Converting: °F = (30 × 9/5) + 32 = 54 + 32 = 86°F. Since 86°F exceeds the upper limit of 79°F, the temperature is out of range and must be reported immediately as an abnormal environmental parameter.
Question 6: A rat weighs 300 g. Its blood volume is approximately 6% of body weight. IACUC policy limits a single blood draw to 10% of total blood volume. What is the maximum volume that may be drawn?
- 0.18 mL
- 1.8 mL (Correct answer)
- 3.0 mL
- 18 mL
Correct answer: 1.8 mL
Total blood volume = 300 g × 6% = 18 mL. Maximum single draw = 18 mL × 10% = 1.8 mL. This two-step calculation protects the animal by preventing excessive blood loss.
ALAT Formulas and Calculations
An animal room is maintained at 68°F.
What is this temperature in Celsius?