The purpose of this assignment is to understand the processes of mitosis and meiosis and the importance of the endocrine system in reproduction.

After completing the Unit 5 Lab on Connect (above), apply critical thinking to answer the following:

1. DDE and Eggshell Thickness: In 1980, there was a major spill of DDT (a persistent chlorinated insecticide) into Florida’s Lake Apopka that caused high rates of mortality in much of the wildlife there. A metabolite of DDT called DDE causes eggshell thinning in birds that eat fish. Role of Calcium in Maintaining Human Bones These birds are affected more than others because they at the top of the food chain and therefore accumulate higher levels of persistent chemicals like DDE. DDE affects calcium movement in the eggshell glands of the birds.

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ANSWER THE FOLLOWING QUESTIONS:

• Describe the role of calcium in maintaining human bones and teeth. Based on this, how do you think a lack of calcium may affect the shells of these birds?

• Predict what will happen when parent birds incubate the eggs.

• Look at the graph attached. Describe how eggshell thickness is related to DDE concentration.

2. Effects of DDE on the Endocrine System: The American alligators (Alligator mississippiensis) that survived the initial spill were found to have high concentrations of DDE in their tissues. Decades later, the alligators in the lake still have DDE in their tissues and their populations do not seem to have recovered to pre-spill conditions. Many juvenile male alligators have low levels of testosterone.

ANSWER THE FOLLOWING QUESTIONS:

• How would low levels of testosterone affect the American alligator population?

• Based on your reading of the materials in this unit, how do environmental factors affect fertility in humans?