g In order to stimulate the renin-angtiotensin-aldosterone system (RAAS), cells in the kidney detect blood pressure which causes to be released from the juxtaglomerular cells.

Macula densa cells, lower and renin.

Explanation:

Macula densa cells in the kidney detect lowers blood pressure which causes renin to be released from the juxtaglomerular cells which is  an enzyme. The arterial cells observe the drop in blood pressure, and the decrease in Na concentration is transfer to them by the macula densa cells. The juxtaglomerular cells then release an enzyme called renin. Renin converts angiotensinogen which is a peptide, or amino acid derivative into angiotensin-1.

1) gene flow

- it is described as the transfer of genes from one population to another population so that frequency of gene is increased.

-a zebra migrates to join a different herd of zebras.

2) natural selection

- a mechanism of evolutionary change in which individuals with advantageous traits survive and reproduce whereas the others ( those that can not adapt) eliminate from the population.

-competition for sunlight leads to taller trees.

3) mutation

- permanent change in the nucleotide sequence of dna ( genetic material) that could have harmful or useful consequences.

-the dna of a snake changes to make its venom stronger.

4) genetic drift - it is a random phenomenon ( that occurs by chance such as fire) that results in change in the gene frequency in a small population.    

-a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

explanation:

oceans

indian ocean

pacific ocean

atlantic ocean

arctic ocean

southern ocean