Distinguish the roles of the soma and the germ line in the life cycle of a typical multicellularorganism. Explain why mammalian gametes are haploid and somatic cells are diploid.

In a typical multicellular organism, the soma and the germ line play distinct roles in the life cycle.

1. Soma: The soma refers to all the cells in the body of an organism that are not involved in reproduction. These are also known as somatic cells. They perform various functions depending on their specific type (e.g., muscle cells, nerve cells, skin cells). Somatic cells are diploid, meaning they contain two sets of chromosomes, one from each parent. This is important because it allows for genetic diversity and the potential for genetic recombination during the process of mitosis, which is how somatic cells divide and replicate.

2. Germ Line: The germ line refers to the cells that are set aside from the soma at an early stage of development and are destined to become the gametes (sperm and eggs). These cells are involved in reproduction. Germ cells undergo a special type of cell division called meiosis, which results in the production of gametes.

Mammalian gametes (sperm and eggs) are haploid, meaning they contain only one set of chromosomes. This is crucial for sexual reproduction because when a sperm fertilizes an egg, the two haploid sets of chromosomes combine to form a diploid zygote. This zygote then undergoes mitosis to form a new organism, starting the cycle again.

In summary, the soma and the germ line have different roles in the life cycle of a multicellular organism. The soma is involved in the growth, development, and day-to-day functions of the organism, while the germ line is involved in reproduction. The difference in ploidy between somatic cells and gametes ensures the correct number of chromosomes is maintained from generation to generation.