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Gram Stains
Microscopy
Anatomy, Shape, Arrangements

Worksheet – Bacterial growth

Section 1

Indicate whether the following statements are True or False.

1. Bacterial growth is measured by following increase in cell size over time.

2. Bacterial growth is followed as exponential population changes over time.

3. The sequence 1-2-4-8-16-32-64 would be considered logarithmic

4. The sequence 1-2-4-8-16-32-64 would be considered logarithmic.

5. Environmental bacteria grow better at 37 C than they do at 25 C.

6. Bacteria have been found growing in ice and in boiling water.

7. Long generation times are expected when optimum growth conditions are provided.

8. The steeper the growth curve slope, the longer it will take to double a bacterial population.

9. Generation time is the time it takes for the population to double in number.

10. Generation time is shorter when there is a higher growth rate.

11. For pathogenic bacteria, incubators lengthen growth rates while refrigerators shorten growth rates.

12. Environmental factors impacting growth rates include temperature, available water, and pH.

13. The amount of Available Water for cells is reduced by adding salt or sugars to a food.

14. The amount of Available Water for cells is reduced by adding acids to a food.

15. The amount of Available Water for cells is reduced by freezing a food.

16. The growth curve for a bacterium in the incubator is steeper than the one for the refrigerator.

17. The growth curve for bacteria in a refrigerator is flatter than for growth on the kitchen counter.

18. When preserving foods, it is unwise to mix strategies for modifying growth conditions for bacteria.

19. The most common approaches to food preservation are addition of salt, sugar, and acids.

20. No matter the strategy used, foods must be refrigerated after opening to prevent spoilage.

21. Our bodies produce unfavorable growth conditions for pathogens by running a fever.

22. Food spoils in our refrigerator because some bacteria are naturally adapted to thrive in the cold.

Section 2

Line G (blue) represents growth of a normal microbe at room temperature. Indicate whether each statement is True or False.

23. Y-axis (A) is a logarithmic scale.

24. X-axis (B) shows elapsed time.

25. Line D’s doubling time is shorter than Line C.

26. Line D’s generation time is longer than Line C.

27. For pathogens, line C would be growth in the body, while G would be growth in an incubator.

28. G represents growth of average-sized bacteria, C is larger bacteria and D is smaller bacteria.

29. Moving the microbe to a refrigerator would change the growth curve from G to look like C.

30. Adding salt to the medium would change the growth curve from G to look like D.

31. Adding acids to the medium would change the growth curve from G to look like D.

32. Curve C shows growth with more Available Water than represented in curve G.