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Lab 21 Notes &amp; Prelab

# Lab 21 Notes &amp; Prelab - Sarah Song BIO 205.33 April...

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Sarah Song April 1, 2008 BIO 205.33 Lab 21 Populations Lab Preparation 3. What was the population of the U.S. in 2003? The population of the U.S. in 2003 was estimated at 294,043,000. 4. What does a negative growth rate of a population imply? A negative growth rate of a population means the population is decreasing. This implies that there are more deaths than there are births over a given time period. What about a growth rate of zero? A growth rate of zero means the population is neither increasing nor decreasing. This implies that the number of deaths is equal to the number of births. There can be either a high birth rate and a high death rate, or a low birth rate and a low death rate. 5. What type of population growth is seen under density independence? Density independence is when population size can change without respect to density if the factor causing the change is not affected by population density. Under density dependence? Density dependence is when regulatory factors increase mortality (or decrease fecundity) with increasing density. 6. What factors could cause variability in the cultures you will grow in Activity 1? The time that one group waits for another group could cause variability. Can you control for these? This could only be controlled for if everyone finishes together. 7. Name two advantages and two disadvantages of using a model to answer an ecological question. Advantages of using a model to answer an ecological question include: giving researchers a pattern to look for where none was visible before by pointing out key components of the system, and simplification. Two disadvantages are that models often do not contain enough reality, and they leave out details that may be important to understand the system. Blackboard Questions 1. What should serve as a blank for the different cells in LB, M9, SOB, SOC? The dilation of XL-1 blue that gives an absorbance of about 0.1 should be used as a blank. 2. Research the ingredients of the 5 types of media (LB, SOB, SOC, TB, and M9 salts) in the Populations lab and their effect on growth of bacteria. Make comparisons of media in a table. State the URL for sources. www.thelabrat.com/protocals.html Media Ingredients Other Effect on Bacteria Growth LB 1. 800 ml H 2 O 2. 10 g Bacto- tryptone 3. 5 g yeast extract 4. NaOH 5. dH 2 O pH 7.5 Promotes growth Nutritious M9 1. 200 ml M9 Salts: 64 g Na 2 HPO 4 - 7H 2 O 15 g 2. 2 ml 1M MgSO 4 3. 20 ml 20% Allows growth

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Sarah Song April 1, 2008 BIO 205.33 Lab 21 Populations KH 2 PO 4 2.5 g NaCl 5.0 g NH 4 Cl Distilled H 2 O glucos e 4. 100 μl 1M CaCl 2 SOB 1. Distilled H 2 O 2. 20 g Bacto- tryptone 3. 5 g Bacto Yeast Extract 4. 2 ml 5M NaCl 5. 2.5 ml 1M KCl 6. 10 ml 1M MgCl 2 7. 10 ml 1M MgSO 4 Inhibits growth TB 1. 12 g Bacto- tryptone 2. 24 g yeast extract 3. 4 ml glycer ol 4. ddH 2 O Allows growth SOC 1. Distilled H 2 O 2. 10 g Bacto
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