❤a tree is planted in a meadow. after 20 years it has grown into a big tree, weighing 250kg more than it was planted. where does the extra 250kg come from? explain fully and scientifically

In natural selection, what is actually “selected? ” a) alleles are directly selected b) genotypes are directly selected c) phenotypes are directly selected d) entire populations are directly selected

Atypical human cell is approximately 12.00 μm in diameter and enclosed by a membrane that is 5.000 nm thick. (a) what is the volume of the cell including the membrane? (b) what is the volume of the cell membrane? (c) what percent of the total volume does its membrane occupy? to simplify the calculations, model the cell as a sphere. enter your answers using four significant figures.

Apopulation of black bears depends on salmon from a stream for food. if a drought causes the stream to run dry one year, how will this likely impact the black bear population?