Homework #9

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Didymo Blooms

In the 21 May 2014 online issue of the magazine Science News an article was published proposing two theories about how didymo blooms are formed. Use the password getting2Darticle to read the article jotting down the theories proposed and the data that is given for the formation of didymo blooms.

After reading the article and the accompanying comment, develop an abduction outline, and turn it in as Homework #9. This outline should include everything that has been required in the last few homework assignments plus a paragraph for each theory describing how each theory does or doesn't meet each of the criterion for scientific merit. See the web pages under "Theories" and Homework #3 for a reminder of what is required. A worked out example is on the last page which is under "Advanced Example" in the menu where it has a full abduction outline for the extinction of dinosaurs. The outline starts with the Initial Observation (you don't need to give a story in the abduction outline).


To simplify the abduction evaluation chart, notate your theories A1, A2, etc. and your data D1, D2, etc. and then use A1, A2, etc. across the top and D1, D2, etc. down the side in your abduction evaluation table. The formatting of such a table could be done by using tabs instead of creating tables. I am not worried about how pretty it is. It is okay if everything doesn't exactly line up!

A1A2A3
D1yesyesno
D2noyesno
D3yesnono
D4yesyesyes

The Hummingbird abduction outline is a good specific example, but remember that for this homework you need to specifically show that each theory meets at least half of the criteria for scientific merit.

Initial Observation

An initial observation is that hummingbirds drink.

Preliminary Conditions

There are two theories posed to explain how hummingbirds drink:

A1: Capillary Action Theory. The water is drawn up small capillaries in the tongue due to the attraction of water molecules to each other.
A2: Micropump Theory. The theory says: "Instead, bird bills squash the tongue and its grooves flat. When the tongue tip touches nectar, the grooves spring open, pulling up a column of nectar as they expand."

Write a couple of paragraphs showing that each theory meets at least half of the criteria for a scientific theory. One paragraph would start out with something like "The Capillary Action Theory is coherent and internally (logically) consistent, it is also consistent with fundamental principles, . . ." Each of the eight criterion should be addressed for each of the theories and the number of criterion being satisfied should be more than half.

Also, each of the theories could explain the initial observation (as described above).

Data (From the Science News article.)

D1: Hummingbirds do this tongue dipping fast.
D2: Hummingbird tongues don't have muscles.
D3: Capillary suction is important in drawing nectar up the grooves.
D4: When tongue met nectar, the fluid moved fast — averaging nearly 1 meter per second as it rose up the tongue. Even under ideal conditions, a simple capillary rise would draw in nectar much slower, only about 36 centimeters per second, the new paper reports.
D5: A bird bumped one side of its tongue against a feeding tube and the tongue’s compressed groove opened prematurely before touching the nectar. In this instance, nectar did a typical capillary rise — but moved more slowly than nectar in the groove on the opposite side of the tongue that sprang open later.
D6: Mathematical models agreed with the micropump theory.

Evaluation Chart

 A1A2
D1noyes
D2yesno
D3yesyes
D4noyes
D5noyes
D6noyes

Result

From this data (Capillary Action - 2, Micropump - 5), it would seem that hummingbirds drinking by using micropumps is the best theory!