Formulae Paper 1

Question 1

Magnification (B1)

Answer 1

Magnification = image size / object size

Question 2

Formula to calculate cross-sectional area of bacterial colony. (B1 RP1)

Answer 2

Pi × radius²

Question 3

How is the number of bacteria in a population after a certain time calculated from the mean division time? (B1 RP1)

Answer 3

1. Calculate the number of times the bacteria will divide in the given time period
   from the mean division time.
2. Use the following equation to calculate the number of bacteria:
   Number of bacteria in population at end of time period = number of bacteria at
   the beginning of the time period x 2number of divisions in the time period.

Question 4

How do you calculate the rate of blood flow?

Answer 4

Volume of blood / number of minutes

Question 5

How would you calculate the breathing rate (B2)

Answer 5

Number of breaths / number of minutes