You have been tasked to estimate the number of rattlesnakes in the desert by Lone Mountain. You capture 42 rattlesnakes and tag them on the first day. You return to the site one week later and capture 59 rattlesnakes. Of the 59 you caught, 21 are marked from the first sample. How many rattlesnakes are in the population?

How are mutations continually being generated in a population (what are some of the causes of mutatuions? ) explain

Give three examples of plant activities that are affected by circadian rhythms and natural fluctuations in the length of daylight?

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?