How does tobacco smoke affect the body? a. it blocks hemoglobin from binding to carbon dioxide, thus affecting gas exchange in the lungs. b. it paralyzes cilia in the bronchi allowing inhaled particles to enter the lungs. c. it causes an increase in heart rate and blood pressure. d. all of the above

How do you transfer mrna into codons ? i'm so confused : (

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?

A. describe the scientific method, using pasteur's swan-necked flask experiment as an example.