Basically we can divide the whole cycle into 6 phrase. menstruation, repair phrase, ovulation, receptive phrase, and pre menstrual phrase, all in this order. usually a cycle takes around 28 days, but it can sometimes be longer or shorter depending on different women. for around the first 5 days (again, it's not exact days) it's menstruation, uterus lining is shed out from the vagina. this only occurs if fertilisation and implantation does not take place. then for the next few days, it's the repair phrase, oestrogen helps repair the lining of uterus, to thicken it up, to prepare for fertilisation and implantation, a place for the fetus to develope. next 3 days will be ovulation, where the ovary will release one mature egg (but sometimes 2 or none) into the oviduct, the egg can only survive for a few days so if fertilisation doesn't occur during this phrase, menstruation will occur that cycle. next will be receptive phrase, where the lining keeps on thickening, and the thickness is maintained by progesterone, another female hormone. at last it's the pre menstrual phrase, lining will start to degenerate unless implantation ocured. hope this helps
When placed into an hypertonic solution, animal cells will shrivel up, while plant cells will stay firm thanks to their air-filled vacuole. In a hypotonic solution, the cells will take on water and appear more plump. In an isotonic solution, they'll stay the same.
In incomplete dominance, neither of the alleles in an heterozygous condition is dominant, thing the organism will show a form of phenotype in which the physical trait expressed is a combination of the two alleles.
Various concept like morphology species concept, ecological species concept was introduced by the scientists to explain the biological species. The biological species concept is accepted today.
The biological species concept explains that the group of interbreeding population that has the ability to reproductively isolated from the other such group.
