A student is observing a sample of pond water and provides the following description in her observations.“I see euglena and paramecium swimming around in the drop of water. A daphnia is feeding on a clump of algae. I see air bubbles around the small clump of algae.”Would you describe what the student saw as a community or an ecosystem? Explain what clue(s) helped you decide.

What kind of crystalline solid is graphite? o a. molecular solid b. metallic solid o c. network solid d. ionic solid

The concept of keystone species is controversial among ecologists because most organisms are highly interdependent. if each of the trophic levels is dependant on all others how can we say one is most important

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.