The correct answer is: desertification.
Desertification is a process in which a land which was not a desert before, becomes one. This process can include drying out- through for example loss of water source, such as river diversion- and the loss of vegetation.
Occurrence: Spermatogenesis occurs inside the seminiferous tubules of a testis whereas oogenesis occurs inside the ovary. The product form in spermatogenesis is sperm which is flagellated i.e. motile and the product form in an Oogonium is ovum which is non-motile.
The theory of evolution proposed that a series of catastrophes or mass extinctions followed by repopulation could explain why species change over time
When using the forced-choice procedure in measuring odor detection thresholds, the experimenter should separate trial by about 30 second Forced force method an experimental methods which help to obtain threshold.For a single interval and forced choice method there they are at least three procedure for collecting data.