Substances that cause DNA mutations are known as mutagens, and mutagens that cause cancers are known as carcinogens. Particular substances have been linked to specific types of cancer. Tobacco smoking is associated with many forms of cancer, and causes 90% of lung cancer.
Human diploid cells have 46 chromosomes and human haploid gametes (egg and sperm) have 23 chromosomes. Retroviruses that contain two copies of their RNA genome in each viral particle are also said to be diploid.
The human egg and sperm cells carry 23 chromosomes. These cells are  considered haploid cells containing half of the number of  chromosomes of other human cells.he sperm contains one copy of each of the 22 autosomal chromosomes and either one X or one Y chromosome. After fusion, these pair up to form a diploid cell, so that there are 46 chromosomes-two of each of the 22 autosomal chromosomes, and either two X chromosomes, or one X and one Y chromosome.