The fossil record of Antarctica shows the presence of tropical plants, such as one particular species related to the present day breadfruit. Most plants cannot survive in prolonged temperatures of less than 6 degrees Celsius. Antarctica is freezing all year round and could only have supported tropical and sub tropical plants if it was once much closer to the equator.
The presence of fresh water species also suggest that the continent was closer to the equator. Antarctica is frozen solid with a thick ice sheet.....rivers would be frozen solid all year round or would be limited to water movement under glaciers that melt as a result of pressure and friction. This environment is not suitable to support large fresh water organisms.
Answer:
If the mitral valve doesn't close properly, systemic circulation will be affected.
Explanation:
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.
A macrophage is a large phagocytic cell that engulfs foreign particles and pathogens. So Macrophage.
Hope this help! :)
