1. Arteries : Carry's blood away from the heart.
2. Veins : Carry's blood back to the heart.
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3. Capillaries : exchange of materials and gases between the cell and vessel takes place here.</span>
Advantage: Dichotomous keys are very useful because they allow non-expert users to identify organisms by directing them to look at the known, important organisms. Disadvantage: Disadvantage of dichotomous keys is that if a single wrong decision is made at any juncture, a wrong identification will result. Sometimes it becomes obvious that an error has been made, and you can retrace your steps until you get back on the right track, but this is not always the case
<span>a.
identifying several solutions to a problem
b.
questioning source information
c.
implementing the first solution to a problem identified
d.
verifying source information</span>
The natural rate of extinction as assumed by science is about 5 species per year. Currently scientists estimate we are losing species at 1000-10000 times that rate, with multiple species disappearing every day. A note on this idea is that the average extinction rate gives an unrealistic depiction of nature when we consider the catastrophic extinction events that ended the dinosaurs and shaped the ice age.
