Why does loss of telomerase activity in humans lead to severe phenotypes in the first generation, while loss of telomerase activity in laboratory mice takes several generations to exhibit any sort of phenotype?

Which mantle is under the crust the upper mantle or the lower mantle i think it's upper let me know if i'm right

Aresearcher has developed two stains for use with seed plants. one stains sporophyte tissue blue; the other stains gametophyte tissue red. if the researcher exposes pollen grains to both stains, and then rinses away the excess stain, what should occur? a) the pollen grains will be pure red.b) the pollen grains will be pure blue.c) the pollen grains will have red interiors and blue exteriors.d) the pollen grains will have blue interiors and red exteriors.

Are the earth's ocean floor and continents the same age geologically? why or why not?