Nonidentical twins occur when a woman produces two separate eggs that are then fertilized by two different sperm cells. The resulting twins sometimes look alike, but have separate genetic identities, like children of the same parents born during different pregnancies. Another name for nonidentical twins is fraternal twins.Know More
Nonidentical twins only form when two eggs release during the same ovulation. In some cases, the eggs release simultaneously. In others, the ovaries initially release one egg. After fertilization that egg begins moving to the uterus to attach. The ovaries then release a second egg, fertilized by a later act of sexual intercourse. This leads to the potential of a woman giving birth to nonidentical twins with two separate fathers. In this case, the genetic identity of the twins is the same as a half-sibling born from separate pregnancies.
The sex of fraternal twins has a chance of differing. Identical twins develop when a single egg fertilized by a single sperm splits to form two different babies. These twins have the same genetic identity. Identical twins are always the same sex.
While some women produce multiple eggs with every ovulation, others begin producing multiple eggs as they grow older. Genetics also plays a role in the chance of conceiving twins. Use of fertility drugs increases the chance of producing more than one egg during each cycle.Learn more about Biology
The exact cause of Siamese twins, more accurately known as conjoined twins, is not entirely known. Since the prevalence of conjoined twins is thought to be higher in southeast Asian and African populations than in Caucasian populations, Sciences 360 suggests that environmental or genetic factors may play some role in the formation of conjoined twins.Full Answer >
Medical professionals use the phrase "gravida 2 para 1" to refer to a woman who has been pregnant a total of two times and carried only one of those pregnancies to the age of viability. Gravida refers to the number of times the woman has been pregnant. Para refers to the number of pregnancies resulting in a birth whether the birth was stillborn or living.Full Answer >
Asthma, diabetes, stroke, cancer, chronic obstructed pulmonary disease and cystic fibrosis are examples of non-infectious diseases, which are commonly known as non-communicable diseases or NCDs. While viral infections, such as the flu, measles and HIV, typically spread from person to person, NCDs aren't contagious and can't be contracted from bacteria. In most cases, NCDs are inherited genetically or develop in response to specific environmental conditions.Full Answer >
A non-living organism is defined as an organism that lacks, or has stopped showing, signs of life. Non-living organisms are inanimate and have stopped displaying capabilities for growth, reproduction, respiration, metabolism and movement. These organisms also lack the ability to respond to stimuli and adapt to their environment. Non-living organisms do not require energy to continue in existence.Full Answer >