A lake in Minnesota was thriving with black bass and bluegill. These particular fish build nests on the sandy bottom of the lake. Now, ecologists are finding that over time a layer of humus has slowly been covering the pond. The ecologists are noting that the populations of black bass and bluegill are declining, and the fish that are able to make nests in humus are rising in numbers. The ecologists can probably conclude that this event is an example of:
commensalism
parasitism
primary succession
succession

In what for do plants utilize nitrogen? why do they need nitrogen?

Aresearcher designed an investigation to test what effect eating different types of food would have on blood insulin levels. she selected 10 male subjects who were all 25 years of age and in good health. the experiment took place over 3 days. at 8: 00 a.m. on each day, the subjects ate a meal consisting of only 1 type of food. they had their blood insulin levels measured after consuming the meal. on day 1 they ate a high fat diet, on day 2 they ate a high protein diet, and on day 3 they ate a high sugar diel what is the independent variable in this experiment? a the age of the subjects b the blood insulin level c the type of food consumed d the time of day the meal was consumed

Which scientific design has both practical limitations and limitations due to scale? studying the effect of bleach on the growth of mold spores exposing cultures of duckweed to different intensities of light observing the replication of dna molecules with a hand lens using colored marbles to model a cross between two colors of rabbits