Expert: Florence M Rollwagen - 9/29/2008

Question
I am a 37 year old college student who needs assistance with 3 questions.

Here are my questions.  

1. Imagine that you have been chosen as the biologist for the design team implementing a self-contained space station to be assembled in orbit.  It will be stocked with organisms you choose, creating an ecosystem that will support you and five other people for two years.  Describe the main functions you expect the organisms to perform.  List the types of organisms you would select, and explain why you chose them.

2. Biologists in the United States are concerned that populations of many migratory songbirds, such as warblers, are declining.  Evidence suggests that some of these birds might be victims of pesticides.  Most of the pesticides implicated in songbird mortality have not been used in the United States since the 1970's.  Suggest a hypothesis to explain the current decline in songbird numbers.  Design an experiment that could test your hypothisis.

3. Birds and mammals have a four-chambered heart, with two ventricles and two atria, but other modern reptiles have a three-chambered heart, with just one ventricle.  Paleontologists debate whether dinosaurs had a typical "reptile-like" heart or a "birdlike" heart. Long-necked sauropod dinosaurs could have had unusual circulatory demands because their head may have been raised far above their heart.  The farther the head is above the heart, the greater the systolic pressure need to be for blood to reach the brain. For example, the long-necked dinosaur Brachiosaurus may have carried its head as much as 6m (20ft) about its heart.  Is is estimated that such an anatomy demanded a systolic blood pressure of 500 mm of mercury for blood to reach the brain!  Some paleontologists consider this to be evidence that dinosaurs must have had a four-chambered heart that supported a dual circulatory system similar to that of birds and mammals, rather than the three-chambered heart of nonbird reptiles.  Can you explain why?


Answer
Hi Alicia:  I'd like to help you, but these questions are very detailed and obviously homework problems.

Why don't you look them up on the internet to get some ideas?  There are probably answers to these questions in your textbook.  Your teacher wants you to figure out the answers for yourself, not just ask someone.

FM Rollwagen, PhD