Vehicle ownership by expats in Saudi. Public transport is almost negligible in Saudi Arabia. As an expatriate, it is really convenient if you have a car of your own. For those of you with your families, it is almost impossible to survive without a vehicle.
Phyla with a true coelom and digestive system are divided into two groups, the protostomes and the deuterostomes. As the hollow sphere of cells known as a blastula develops, an invagination produces an opening called the blastopore. In protostomes, the blastopore becomes the mouth.
Genes are segments of DNA arranged along a chromosome. A single chromosome can have hundreds or even thousands of genes. Most sexually reproducing organisms, like people and pigeons, have two copies of each chromosome, called homologous chromosomes. Humans have 23 chromosome pairs, or 46 chromosomes in all. Homologous chromosomes have the same genes arranged in the same order, but they have slightly different DNA sequences. Different versions of the same gene are called alleles (uh-LEELZ); homologous chromosomes often contain different alleles.