Which of the following is true about soil color? a. Soil vary in color based on their mineral content. b. Soils do not vary in color based on their minimal content. c. Soils consisting of only a few minerals are always darker. d. Soils is consisting of many different minerals are always darker.

Which statement is true about the cell theory? a) it is well-supported by evidence. b) it is unchangeable and permanent.

Use the phylogenetic tree to the right to determine which statement below is true. organisms a and f are not related. organism e is more closely related to organism b than organism f. organisms c and d are more closely related than organisms a and b. phylogenetic trees

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?