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Populations and sustainability

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Question 8

A student is studying the population growth of a yeast culture.

a.

The student prepared a starter culture by adding 2.5 × 10-5 g of dried yeast cells to 1 dm3 of nutrient broth. The average dry mass of a single yeast cell is 2.5 × 10-11 g. Calculate the initial number of yeast cells in this starter culture. Give your answer in standard form.

[2]
b.

Under ideal conditions, the population of this yeast doubles every 45 minutes45\text{ minutes}45 minutes. Using a starter culture containing 1.0 × 106 cells, the student plots the log-transformed population size, log⁡10(number of cells)\log_{10}(\text{number of cells})log10​(number of cells), against time ttt (in hours) over the first 15 hours15\text{ hours}15 hours. Determine: * The coordinates of the starting point of the growth curve at t=0 ht = 0\text{ h}t=0 h. * The coordinates of the ending point of the growth curve at t=15 ht = 15\text{ h}t=15 h, using the standard biological approximation 210≈1032^{10} \approx 10^3210≈103. * Description of the shape of the growth curve under these ideal conditions.

[5]

Populations and sustainability Questions

  1. A Level
  2. /Biology
  3. /Populations and sustainability