The annelid worm Glycera dibranchiata has an oxygen binding protein with the same folding pattern as myoglobin. Myoglobins and hemoglobins occur sporadically among invertebrate phyla. It is hard to see a clear, common line of decent from a single ancestor for these species let alone annelids, insects, and vertebrates. No other known protein form has oxygen binding capability. How might these observations best be explained.

Apopulation of black bears depends on salmon from a stream for food. if a drought causes the stream to run dry one year, how will this likely impact the black bear population?

Which statements best describe the differences or similarities between a comparative investigation and an experimental investigation? check all that apply. experimental investigations are best for showing cause-and-effect relationships, while comparative investigations do not necessarily show this type of relationship. comparative investigations are often impractical and unrealistic, while experimental investigations are the most practical and realistic kinds of investigations. comparative investigations allow for the use of a wide range of variables but do not have a control group, while experimental investigations involve variables that can be controlled. both experimental investigations and comparative investigations are designed to answer scientific questions. both experimental investigations and comparative investigations focus on making observations rather than collecting new data.

Which of the following types of stars are dim but can have high surface temperatures? giants main sequence stars supergiants dwarfs