Which microscope did anton van leeuwenhoek use to observe single-celled organisms?

When the cell concentrates potassium within, against the natural tendency of matter, it is performing a.passive diffusion b.facilitated diffusion c.active transport d.pinocytosis

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?

Apower company wants to build a power plant on the severn river in france. read the following details about the plant and then answer the question that follows: the plant will -provide 10% of the country's energy needs - has a tide amplitude of 11 meters - will be built across a narrow inlet (15 kilometers) -could reduce coal emissions in the area by 3 percent by replacing fossil fuel power - will alter the feeding grounds of local birds. it is unknown how these birds would adapt. fish in the inlet are able to pass through the turbines. occasionally, however, they can get trapped and die do you think this tidal power plant should be built? why or why not?