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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.
both alleles in the heterozygous
genotype are exhibit in the phenotypes. Allele
is completely dominant over the other, and it is the phenotype is a blend of the two
homozygous phenotypes, there are more than two forms of the same gene, and
there maybe one more superior form and several different phenotypes
The uterus relaxes is muscles after being stretched open. When the baby is about to be pushed out, the uterus contracts many times until the baby is out of the female's body.
The answer is letter a. loop
