Sexual Reproduction

Sexual Reproduction
Sexual reproduction is characterized by processes that pass a combination of genetic material to offspring, resulting in diversity. The main two processes are: meiosis, involvingthe halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the restoration of the original number of chromosomes. During meiosis, the chromosomes of eachpair usually cross over to achieve homologous recombination.

Asexual Reproduction
Asexual reproduction is reproduction which does not involve meiosis, ploidy reduction, or fertilization. Only oneparent is involved in asexual reproduction. A more stringent definition is agamogenesis which refers to reproduction without the fusion of gametes. Asexual reproduction is the primary form ofreproduction for single-celled organisms such as the archaea, bacteria, and protists.

Body System
Digestive System
The digestive system is made up of the digestive tract—a series of hollow organs joined ina long, twisting tube from the mouth to the anus—and other organs that help the body break down and absorb food. Organs that make up the digestive tract are the mouth, esophagus, stomach, smallintestine, large intestine.

Respiratory and Circulatory System
The respiratory system's function is to allow gas exchange to all parts of the body. The space between the alveoli and the capillaries,the anatomy or structure of the exchange system, and the precise physiological uses of the exchanged gases vary depending on the organism. In humans and other mammals, for example, the anatomicalfeatures of the respiratory system include airways, lungs, and the respiratory muscle.

Nervous System
The nervous system is a network of specialized cells that communicate information about anorganism's surroundings and itself. It processes this information and causes reactions in other parts of the body. It is composed of neurons and other specialized cells called glial cells that aid in the...