Animal Physiology

A consequence of proportion (10 pts)

 

Animal boxeus: -Leg strength (10 pts)

  1. You are provided with two ‘animals’ of the genus boxeus. They should be of the same relative, but not exact, shape. They are filled with a material about the density of an animal (e.g. water) (don’t poke the box or over manipulate or you will get wet).
  2. Measure the dimensional lengths of the big and small animal boxeus . Determine the dimensionality ratio (it should be close to 10 times). Calculate the corresponding surface areas. Weigh the big box relative to the small box. Calculate the densities. Put all of this information in a neat computerized table.(see For your report below for the desired format of your report.) Also include in your table the leg sizes (see below) and if they successfully "held" or not. Also include a column in your table of the factor by which each factor increased in going from the small boxeus to the large boxeus. Make sure to include in your discussion what your expectations should be (and the basis for those expectations) and if the data supported those expectations.
  3. Construct four legs out of clay for the small animal boxeus with dimensions of 10 mm in length and 2 mm in diameter. Support the animal with these four legs.
  4. Construct four legs out of clay for the large animal boxeus with dimensions of a larger size of the dimensionality ratio that you measured above (e.g., if the dimensionality ratio is 10 then the legs should be 100 mm in length by 20 mm in diameter). Try to support the large animal boxeus with these legs. Record your observation into your table above. As part of your discussion, calculate and report the diameter the legs would have to be for large boxeus to have the same support strength as small boxeus (hint strength of supports or a hanging object, such as a rope, is proportional to the cross sectional area. Does this make sense?) Optional: you may go ahead and try making the larger legs to see if they work.
  5. We expect that boxeus should follow the relationship of

    6. Mass = constant (length)3.

  6. In your discussion, for each boxeus calculate this constant (and its units) (for "length" use the longest dimension.)

MINNOWS(10 pts): Mass relative to length and log-log plots.

1. Accurately measure the mass and length of at least 15 available fish (generically being called minnows.) going from smallest to largest.

2. Make a computerized a linear plot of length (x-axis) versus mass (y-axis). (On Excel use Scatter with a smooth connecting line; you may need to have Excel sort your data first). Take the log base 10 of all of your data (Excel can do this) Make a log-log plot of the length (x-axis) versus mass (y-axis) of minnows. Do a least squares best fit straight line to the log data. Have Excel place the slope, intercept and R2 value of your line onto your chart. Do the same, except make a log-log plot of the mass (x-axis) versus length (y-axis). Discuss why the first plot should be curved and why the last two should be linear . Discuss if this slope, intercept and R2 values for the last two plots are what you expected (within experimental error). What does the slope and intercept mean?

EGGS(10 pts): Consequences of dimensions.
  1. Acquire a chicken egg. Try to have it be significantly different in size to your partner's egg. Read the Scientific American Article "How Eggs Breathe" (Feb. 79)
  2. Weigh the egg and record the mass.
  3. Measure its length and width.
  4. Measure the volume of the egg.
  5. Determine the density of the egg (extra credit if you also innovate an accurate way of actually measuring (rather than just calculating from volume and mass) the density directly).
  6. Measure or determine the surface area of the egg.
  7. Carefully break the egg and separate the yolk, white and shell.
  8. Weigh separately the shell, yolk and white.
  9. Measure the thickness of the eggshell using the available micrometer.
  10. Put your actual measurements in the left column below.
  11. Indicate how you made each measurement and what assumptions you may have had to make.
  12. Find another person who has done similar measurements and put their data in the table below under actual measurements of "partner’s egg"
  13. Using a) your actual measurement for each criterion, b) the length of your partner’s egg as related to the length of your egg, and c) exponential or proportional predictions (as appropriate) THEN calculate a predicted value for your partner’s egg for each criterion. (For example the width is just a proportionality of the width while the predicted mass equals your mass times your partner’s egg’s length cubed divided by your length cubed.) Show example calculations. For your report you will compare the predictions to the actual measurements. Put the predictions in the below table.
  14. Assume the length of a dinosaur egg is 20 cm. Again using a) your actual measurement for a certain criterion, b) the assumed length of a dinosaur egg of 20 cm, and c) exponential prediction THEN calculate a predicted value for the dinosaur egg for that criterion. Put the predictions in the below table (or one like it).
    15.
     

    Actual Measurements

    Predictions

    criteria

    your egg

    partner’s egg

    partner’s egg

    dinosaur

    Length (cm)

    		    

    ----

    20

    Width (cm)

    		        

    Mass (g)

    		        

    Volume (ml)

    		        

    Density (g/ml)

    		        

    Surface area (cm2)

    		        

    Shell mass (g)

    		       

    Yolk mass (g)

    		        

    White mass (g).

    		        

    Shell thickness (mm)

    		        
  15. Discuss if your predictions for your partner’s egg match the actual measurements for your partner’s egg within experimental error?
  16. Having read the article and looking at their numerical relations, discuss what physiological considerations need to be considered regarding the shell thickness of an egg?
  17. Having read the article, considering the values you determined for the dinosaur egg, and the answers to the previous question, discuss if you think there is a physiological limit of how large an egg can be and still survive.

FOR YOUR REPORT:

Do this report in a lab report format as indicated below. Many hints and requirements are given above as to some things that are minimally expected.

Purpose: A one to two sentence statement as to the goal of the experiment.

Materials/Methods: Include how you did the experiment so that another person could reproduce it. You may refer back to the handout given to you, but you will need to state how you did things not specified in the handout (e.g., dried minnows?, How did you determine density? …). Do NOT include results or discussion in the methods section.

Results: Tables and graphs generated by a computer (with appropriate legends and titles) (refer back to cell bio handout on making good graphs and tables. http://www.morris.umn.edu/~goochv/graphing.html). It is not uncommon that the graphs and tables cover all of your results and additional words may not be needed.

Discussion: In a discussion you want to discuss your hypotheses/expectations, the basis for those hypotheses/expectations, and did your results match those hypotheses/expectations. You also generally want to discuss experimental error, possible problems encountered during the experiment, and ways to improve the experiment if it were redone. Many hints are gi

Always feel free to talk to me if you need help on any aspect of your lab reports.