CURRENT CONCEPTS IN BIOLOGY
CURRENT CONCEPTS IN BIOLOGY BIO 380T
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This 2 page Class Notes was uploaded by Ezequiel Orn on Sunday September 6, 2015. The Class Notes belongs to BIO 380T at University of Texas at Austin taught by Staff in Fall. Since its upload, it has received 34 views. For similar materials see /class/181738/bio-380t-university-of-texas-at-austin in Biology at University of Texas at Austin.
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Date Created: 09/06/15
Investigation 24 ENVIRONMENT AND NATALITY Selection by the abiotic environment INTRODUCTION Brine shrimp are small aquatic animals that live in such places as Great Salt Lake Utah Unlike the eggs of most other aquatic animals those of brine shrimp can survive drying Indeed the dried eggs may still hatch after a year or more This fact has made the eggs useful to tropical sh fans for the eggs can be kept easily until needed then hatched and used as food A number of environmental factors in uence the hatching rate natality of brine shrimp eggs Read the following procedure 1 Then state one or more hypotheses concerning the relation of environmental factors to brineshrimp natality MATERIALS per team glassmarking crayon 6 petri dishes graduated cylinder 1 distilled or deionized water sodium chloride solutions 1 2 4 8 16 10 ml of each volume measure medicine dropper with mark 3 mm from tip brineshrimp eggs refrigerator incubator stereomicroscope medicine dropper PROCEDURE 1 Using a glassmarking crayon number 6 petri dishes on the rims of the bottom halves Place your team symbol on each dish Mark a large on the bottom of each dish to divide it into 4 quadrats Number the quadrats from 1 through 4 2 Four 10 ml of distilled or deionized water into Dish 1 3 Into Dish 2 pour 10 ml of 1 sodium chlo ride salt solution 4 Into Dishes 3 through 6 pour 10 ml of 2 4 8 and 16 sodium chloride solutions respectively 5 Using the volume measure measure dry brineshrimp eggs as directed by your teacher Scatter them on the surface of the water in Dish 1 Scatter the same volume in each of the other dishes 6 Cover the dishes and stack them in the place designated by your teacher Some teams dishes will be left at room tempera ture Some will be placed in a refrigerator and some in an incubator at a temperature 100 to 15 C above room temperature 7 Check the temperature at the place where your dishes are to be kept and record it in your data book 8 Recheck and record the temperatures on each of the following 2 days 9 Two days after setting up the cultures use a stereomicroscope to count the hatchlings in each dish You may find that a rough count wilt be satisfactory Or you may use a medicine dropper to remove each young brine shrimp as it is counted The on the bottom of the dish will help you to be sure you check the entire dish Record each number indicating whether an estimate or a count in your data book DISCUSSION Assemble data from all teams on the chalk board For each of the 3 temperature conditions the data for each of the 6 dishes Then calculate an average for each dish Set up your graph with the number of individuals on the vertical aXis and salt concentrations on the horizontal axis Use Os to plot the points for the lowtemperature dishes Use X s for the roomtemperature dishes and s for the hightemperature dishes Connect the D s with l tine the X s with a 2nd line and the s with a 3rd line 2 What conclusion can you make about the effect of temperature on brineshrimp natality 3 About the effect of salt percent age on brineshrimp natality 4 Do your data indicate any interaction of temperature and salt percentages I