1st Planning Lab- The effect of testing your variable on brine

shrimp cyst hatching

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I. Introduction p1

A. Purpose - to study the effect of a variable on brine shrimp hatching

B. Background- brine shrimp live in the ocean, they lay eggs that arrest in their development until favorable conditions

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• Cysts hatch better if they are attached to a substrate (we’ll stick them using tape)

• If they start developing- they emerge after 24-48 hours depending on temperature.

C.Hypothesize or predict the result for your variable state why (state reference)

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YOUR Mission:

• With your lab partners decide what environmental condition you will be testing next Wed.

• Write up your prelab (Part I & II of formal lab report)

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II. A. Materials p 2 of lab notebook• Instant Ocean• 2 plastic petri dishes• Scotch double-stick tape• marking pen• Paint brush• brine shrimp dried cysts -- “Artemia

franciscana” • disposable plastic pipet• transparency sheets with multiple 10

mm X 10 mm grid patterns copied on surface

• dissecting microscope with light source

II. B) Method (p 2 of nb)List the steps to do the lab as described.

1. Get materials2. Put double stick tape to grid3. Add 80-100 brine shrimps carefully to grid using dissecting scope

(do not overcrowd eggs or add too many) 4 Record the number of cysts in table.5. Repeat for a second grid6. Label 2 petri dishs (control & exp) w/ name etc on the side of dish7. Tape a second strip of tape on bottom of grid and fasten grid to

bottom8. Add 20 ml of instant ocean to control 9. Add______ to experiment 10. Put dishes into an incubator and observe eggs on Day 2 & 3

II. C Table of variable (2nd page)• Independent Variable- you decide how to

treat experimental group of brine shrimp. – Example The experimental group will be

exposed to instant ocean dissolved in tap water to determine the effect of chlorine.

Table of variable hints• Dependent Variable- What are you

measuring?

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Table of variable hints• Controlled Variable- How are you making

sure the control petri dish is the same except for the independent variable. Use full sentences

Example- Temperature is kept constant between control and experimental plates by placing them next to each other in the same region of classroom

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control

experiment

III. Results put on p 3 • A) Qualitative- note observations

– Day 1 We accidentally crushed the eggs or some cysts floated off the tape when instant ocean was poured into petri dish

– Day 2- Only a few brine shrimp were hatching from the eggs. We noticed some nail polish in the solution.

III. Results put on p 3 B) Quantitative

Title: The effect of __________ on brine shrimp hatching

# of brine shrimp cysts (Day 1)

# of unhatched cysts

(Day 2)

# of unhatched cysts

(Day 3)

Control 80 +/- 1 63 +/-3 45 +/- 6

Exp.- shrimp treated to:

83 +/- 1 80 +/- 4 78 +/- 5

III. B. Data Analysis (new page)• Transformed Data- use some kind of

calculation- put into tables & graphs

• Table II- Brine shrimp hatching percent in instant ocean vs. _________ (independent variable)

% of brine shrimp hatched

Control (instant ocean)

80% +/- 10%

Experimental (treated to:____)

10% +/- 15%

Write out a “Sample Calculation”• Show how you calculated your results• % brine shrimp hatched• = (original # of cyst - unhatched cysts)/ (original number) x100 %

• If you have 100 cyst originally & 20 eggs on your grid then

• = (100-20)/(100) x 100%

• = (80)/100 x 100%

• = 0.80 x 100% = 80%

Uncertainty sample calculation

• If you have 10 brine shrimp eggs that you are not sure hatched out of 100 original eggs, your uncertainty = 10 cysts

• = 10/100 x 100 % = 10% uncertainty• Use this for your error bar on your bar

graph

The effect of microwave radiation on brine shrimp hatching

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Control Experiment

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% hatching rate

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% of brine shrimp hatched

Control 80% +/- 10%

Exp. 10% +/- 15%

The effect of microwave radiation on brine cyst viability

Is there significant difference here between control and exp?

The effect of microwave radiation on brine shrimp hatching

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Control Experiment

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Conclusions (new page in notebook!)

• Paragraph 1- A. What did you do in the experiment? How did you perform the experiment in general? What happened in the experiment?

• P2- B. Did the experimental condition have more or less % hatching than compared to the control? Refer to your Graph! By what %? Is this a significant difference (- look at your error bars)?

Conclusions (new page in notebook!)

• P3 C. What did you predict- restate your hypothesis. Did the results match what you predicted? Does data support or falsify your conclusion- or is your data have so much uncertainty that you can not make a conclusion. Compare your data to other students in the class- is it similar? Compare your data to reports of brine shrimp hatching rates (look up data on web & cite it here!) This also should have been mentioned in your background.

Conclusions (new page in notebook!)• P4 D. What were the errors in this lab

(discuss at least 3!)? What were the limitations of this lab? Were you able to obtain data accurately- if not Why? Could there be a better way?

• P5 E- for every error you wrote above- suggest a realistic way to fix the problem. For every limitation stated in the above paragraph, suggest a better way to perform this experiment.

Bibliography

• See the Biology Lab Report Guidelines • I have extra copies if you lost it- or down load

from Bio ACC assignments & syllabus from web site (teacher web.com).

• Please staple to lab notebook. • Follow the citation examples.

Formal Lab due-see syllabus

• Good Luck!