Which of these is not a chordate characteristic across all its phylum?

Which organelle is found uniquely in autotrophic, eukaryotic cells and not heterotrophic, eukaryotic cells? 

The periodic table provides us with:

In humans, blood returning to the heart from the lungs enters which chamber of the heart?

 This map illustrates the number of amphibian species across the globe.   A similar pattern is observed for most taxonomic groups. Using the color coded key, what trend do you see?   

The relative energy in trophic levels in the Silver Springs, Florida, ecosystem is shown.  Refer to the diagram below:   

Which of these levels of ecological study involves an interaction between abiotic and biotic components?

Which of these levels of ecological study involves an interaction between abiotic and biotic components?

Fluctuations in population growth can correlate to changes in:

Living organisms on Earth share many common characteristics. Concerning all living things, which statements  are True or False: