Generally, the valence electrons determine most of an atom's chemical properties
when changes in a protein appear to accumulate at a constant rate over time is called option (c) i.e, Molecular clock.
<h3>What does molecular clock mean?</h3>
The term "molecular clock" refers to a method that estimates the time in prehistory when two or more life forms diverged by analyzing the mutation rate of biomolecules. Typically, nucleotide sequences for DNA, RNA, or amino acid sequences for proteins serve as the biomolecular data for these calculations.
Hedges, a biology professor at Penn State, claims that the molecular clock counts the mutations that accumulate through time in the gene sequences of various species rather than counting seconds, minutes, and hours.
Mutation and recombination, the two fundamental biological processes that give rise to all heritable variations, are the foundation of molecular clocks. Mutations are modifications to the genetic code of DNA, for as when the nucleotide Guanine (G) turns to Thymine (T).
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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