The mechanisms of reproductive isolation prevent the reproduction of two individuals from different species. The prezygotic mechanisms disrupt the stages of reproduction before the forming of the zygote or prevent the mating at the start, and the postzygotic mechanisms affect the stages of reproduction after the forming of the zygote.
So, the first and the third example (the urchins and the grasshoppers) show the prezygotic mechanism, as the two individuals are not able to mate or form a zygote.
The second and the fourth example ( zonkey and the death of a zygote) show the working of the postzygotic mechanisms, as the zygote is formed, but it seems to be inviable, and the zonkeys are sterile, preventing the individual to reproduce.
I’m not entirely sure but I think it’s eyes to the brain
Auroras normally occur in the Earth's thermosphere.
A compound is organic if it contains carbon covalently bonded to other atoms. Most often, the other atoms include hydrogen, oxygen, and/or nitrogen. A few carbon compounds, such as simple oxides (e.g. CO2) and cyanides (e.g. KCN) are excluded arbitrarily.
I don’t know sorry, I hope the person above me is correct. If they’re not sorry I can’t help :(
