An ecologist wanted to know how many plants lived in a particular prairie. Instead of counting all the plants, the ecologist used a sample area. The ecologist placed a grid that was ten meters by ten meters in a random location in the prairie and counted the number of individual plants of the various species. Data were collected and recorded. Answer these:
Describe an observation from the prairie sample study.

Describe an inference from the prairie sample study.

Describe a difference between any observations and any inference

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?