3- Considera os seguintes isótopos radioativos e os respetivos tempos de semivida: Isótopo pai Isótopo filho Semivida (anos)
40K 40Ar 1,4x109
235U 207Pb 0,7x109

3.1.1- Foi feita a análise da desintegração de átomos de 40K contidos em minerais de uma amostra de rocha, tendo-se verificado que a desintegração se iniciou há 2,8x109 anos. Indica, justificando com todos os cálculos, a percentagem de átomos de 40Ar existentes nessa amostra de rocha.

How does the molecular clock work? a. it analyzes the brain functionality of two different species.b. it examines and compares the physical characteristics of two different species.c. it illustrates relationships between two different species.d. it compares the number of mutations that exist in the dna of two different species.

Humans are believed to have evolved in coastal regions in east africa. the region had an abundant supply of fish for early humanoids to eat. when scientists analyze the fads gene they see an interesting pattern. people whose families have lived in this area of east africa for generation show a high level of diversity in alleles for the fads gene. conversely, people whose families had migrated inland a moderate distance from sources of fish showed a much lower diversity for fads gene alleles. additionally, the fads alleles found in people whose family has lived inland for generation are almost all gene alleles which produce fads proteins with a high level of function and activity. how do anthropologists explain this?

Explain how organisms could be harmed by high levels of salt from roadways?