Saori T.

asked • 12/13/13

I have a question about a practice test!! Why is the correct answer D? I choose A.

Changes in the weather can trigger the start of the journey south, although birds in the Northern Hemisphere seem to know when it is time to migrate south before the winter. In some species at least, the changes in the length of the day cause glands in the birds' bodies to secrete hormones that produce other changes, which ready the birds for the long flight south. At this time fat starts to accumulate under the skin, and this provides a store of energy for the long flight when they will be expending more calories flying than they can obtain during their brief rest stops.
 
 
According to paragraph 2, what are the results of changes in the weather?

A, The change in the length of the day

B, The secretion of hormones by the birds

C, The expenditure of calories

D, The onset of migration

2 Answers By Expert Tutors

By:

Naina B. answered • 12/14/13

Tutor
4.8 (155)

Naina, a versatile tutor

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