A diploid organism receives two forms of gene called ALLELE, one from each parent. These genes are passed on by parents to their offsprings as chromosomes on long strands of DNA.
According to Mendel's law of segregation, these alleles get separated into gametes during meiosis. Meiosis a cell division that results in daughter cells (gametes) that has half the number of chromosomes as the parent cell.
During meiosis I, homologous chromosomes i.e. similar but non-identical chromosomes received from each parent pair up. These chromosomes (homologous) contains the same genes coding for the same trait but may be in different forms (alleles). The chromosomes containing these alleles get randomly separated into individual cells (gametes) during anaphase of meiosis.
Hence, a gamete receives one allele for each trait.
During exhalation, the diaphragm also relaxes, moving higher into the thoracic cavity. This increases the pressure within the thoracic cavity relative to the environment. Air rushes out of the lungs due to the pressure gradient between the thoracic cavity and the atmosphere.
