community that has 4 trophic levels, what biomass of primary producers is necessary to maintain a tertiary consumer biomass of 1.78 kg/m^2? *

Many cultures and religions have customs which deal with the way they use the land. For example, in Judaism, it is required that a field be left fallow (unplanted) every seventh year. What is one beneficial effect of customs like this?  A) They prevent the land from being overused. B) They cause less competition among farmers. C) They make the land more valuable to farmers. D) They force people to farm more recklessly at other times. (Not Graded)

In 2016, Costa Rica had a doubling time of 70 years. Calculate the growth rate. Doubling time = 70/growth rate A. 4% В. 1% С. 5% D. 2%

1) How could your eco-column be used to model the greenhouse effect? 2) Describe how your eco-column is used to model the nitrogen cycle. 3) Describe at least 3 transformations of nitrogen occuring in your eco-column and the organisms assisting in the transformation of nitrogen.

Why do some species tend to grow exponentially while others tend to follow a logistic growth model?

3)"Ecosystem engineers" are a special group of keystone species a)True b)False

Why is the change in human footprint relatively low for the most agriculturally suitable land? a) Very little of the land is highly suitable for agriculture b) Cities put little pressure on the environment, and tend to be in very agriculturally suitable areas c) Pressure was already high there

Which of these is not an abiotic factor that effects population dynamics? a) dispersal b) disturbance c) dissolved oxygen d) nutrients e) energy

Which of the following would be considered a bad predictor of environmental conditions that a) dry and wet seasons b) average yearly rainfall c) flooding d) seasonal changes in day length

Please help with explanation