25. en qué etapa los cromosomas se hacen visibles al microscopio

Any sound above what db can cause hearing loss in human beings

Ivan is looking at a cross section of a stem taken from a vascular plant. he sees two different types of vascular tissue: the xylem, which is closer to the center of the stem, and the phloem, located around the xylem, closer to the outside of the stem. how do these two structures work together in a living plant?

Natural selection changes allele frequencies because some survive and reproduce more successfully than others.