Answer:
An adaptation can be viewed as a trait that emerged and developed for a certain condition so as to increases the organism changes of survival or fitness.
For a trait to be called adaptive, it must have had a positive influence but not majorly a trait that develops in reaction to a certain selection pressure.
Categorically, a trait is seen as adaptation if it is the aftermath of selection, and adaptive if it is of favourable influence at the existing time.
If the sperm cell fertilises the ovum, and implantation does not occur, then the corpus luteum degenerates and it turns into corpus albicans, stopping progesterone secretion. If fertilisation occurs and implantation also, the syncytiotrophoblast, the "root part" of the blastocyst (one of the early structures originated from the zygote), produces a hormone that is called <span>human chorionic gonadotropin (hCG). The hCG is what makes the corpus luteum keep secreting progesterone and maintain itself. The progesterone will then help keep the endometrium and, therefore, allow the development of the embryo to happen.</span>
<span>It is process through which plants and other photoautotrophs generate carbohydrate and oxygen from carbon dioxide, water and light energy in chloroplast. It is two stage reaction-
1.Light dependent reaction- in this sunlight is absorbed by chlorophyll and converted into chemical energy and stored in the form of NADPH and ATP. It takes place in thylakoid membrane in chloroplast.
2.Light Independent Reaction- in this energized electrons from the light dependent reaction provides the energy to form carbohydrate from carbon dioxide molecules. It is known as Calvin cycle.</span>
