Which ecological principle is probably responsible for the lack of reptiles and amphibians in the tundra?

air, water and soil are essential to life
single species systems are more fragile
extremes of conditions determine suitability of a habitat
all organisms must be linked to the food chain

The model illustrates a process by which a substance is taken up by a cell

What is the best conclusion based on this data? the hypothesis was not supported because the data indicated that fertilizing plants does not improve plant growth. the hypothesis was supported; to get the best growth, use 5 milliliters of fertilizer per plant. the hypothesis was not supported; the data indicated that too much fertilizer can inhibit plant growth. the hypothesis was supported; to get the best growth, use 15 milliliters of fertilizer per plant.

The law of thermodynamics states that energy can't be created or destroyed. to natural sources of energy on earth are the