STUDY GUIDE A2 (76-108) and 2 (76-111), SELF TEST 3

© Department of Physics, University of Guelph.

Select the problem number or part you wish.

1. Plot a graph of N = 3e-3k. Show the coordinates of at least 3 points.

2. You are working with 2 cell cultures, X and Y. Culture X has a growth constant of 0.0124 day-1, and a present population of 1286. Culture Y has a decay constant of magnitude 0.186 day-1, and a population of 1573.

(a) Plot a graph of the populations of both cultures over the next 5 days, and also over the 5 previous days.
(b) From your graph, estimate when the populations will be equal.
(c) Check your estimate in (b) by calculating when the populations will be equal.
(d) From your graph estimate when there will be twice as many cells in Y as in X.
(e) Calculate when there were twice as many cells in Y as in X.

3. Yet another culture C12, has a growth constant of 0.200 day-1 when supplied with proper nutrients. Without nutrients, the population decays by a factor of 3.50 every 6.00 days. Exactly 1 day ago, culture C12 was provided with enough nutrients for 4.00 days. Its present population is 852.

(a) Plot a graph of population starting with time = 0 at 1 day ago, and ending 11 days from now.
(b) From your graph, estimate when the population will have declined by 40% from its present value.
(c) Calculate when the population will have declined by 40% from its present value.

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