Researchers manipulated the tail length in male widowbirds and compared female preference for birds with differing tail lengths. Do the results that are reported in the figure below show that male tail length is an hon-est signal of male quality?
a. Yes, females would otherwise not prefer males with longer tails.
b. Yes, the longer the tail the more energy males need to spend on growing it.
c. No, just putting a longer tail on a male does not increase its quality.
d. No, this study did not test whether birds with naturally long tails were of higher quality than birds with naturally short tails.
D
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Suppose you are studying the nitrogen cycling in a pond ecosystem over the course of a month. While you are collecting data, a flock of one hundred Canada geese lands and spends the night during a fall migration
What could you do to eliminate error in your study as a result of this event? A) Find out how much nitrogen is consumed in plant material by a Canada goose over about a twelve-hour period, multiply this number by 100, and add that amount to the total nitrogen in the ecosystem. B) Find out how much nitrogen is eliminated by a Canada goose over about a twelve-hour period, multiply this number by 100, and subtract that amount from the total nitrogen in the ecosystem. C) Find out how much nitrogen is consumed and eliminated by a Canada goose over about a twelve-hour period and multiply this number by 100; enter this +/- value into the nitrogen budget of the ecosystem. D) Do nothing. The Canada geese visitation to the lake would have negligible impact on the nitrogen budget of the pond. E) Put a net over the pond so that no more migrating flocks can land on the pond and alter the nitrogen balance of the pond.
Focusing on an object requires the interaction of the ____ and the ____
a. ciliary muscles; lens b. ciliary muscles; cornea c. ciliary muscles; iris
d. iris; pupil e. cornea; pupil
This illustration shows the mechanism of
a. simple diffusion. b. bulk flow. c. endocytosis. d. facilitated diffusion. e. an active transporter.
The __________ circuit carries blood from the heart
to body tissues, and then returns it to the heart. Fill in the blank(s) with the appropriate word(s).