Which is not an example of matter and energy cycling through living things? a. trees growing b. plants absorbing carbon dioxide? c. salmon eating shrimp. d. a drop of water falling through the sky?

Body temperature is tightly regulated in mammals for example when external temperatures drop too much the body of a mammal responds by in order to its core temperature?

Which greenhouse gas is emitted when burn fossil fuels for energy? a.nitrogen b.oxygen c.carbon dioxide d.helium

Astudy by solloch and et. al., in 2017, gives the map above which shows the frequency of alleles with a ccr5-delta32 mutations over 87 different countries. this mutation deletes the presence of a co-receptor (ccr5) on the outside of human t-cells (lymphocytes). some viruses, such as the one responsible for the black death and human immunodeficiency virus (hiv), require this receptor for attachment to host cells during the infection process. the black death was an epidemic that passed over northern europe during the 14th century killing nearly 60% of europeans. according to this information, which explanation best explains why northern europeans show a greater immunity for hiv than some other parts of the world?