In humans, red blood cells are the only cells that eject their nuclei as they develop. By emptying themselves of nuclei, these cells are able to do which of the following?
replace themselves quickly when more cells are needed
transport greater amounts of oxygen and waste throughout the body
transmit electrical impulses quickly
attack bacterial pathogens more effectively

Recent research by marine biologists suggests that bottlenose dolphins have names for themselves. scientists played sounds they had identified as the names of particular dolphins, putting them through a synthesizer so that they did not sound like the voices of particular dolphins. the researchers found that dolphins would respond to the names of other dolphins that they were related to or associated with, but they ignored the names of strangers. this discovery suggests a much greater degree of self-awareness in aquatic mammals than was previously suspected. if this research holds up, what does it suggest about dolphins?

What would be the result if crossing over did not happen during meiosis in humans? a. there would be less genetic variation in humans. b. parents would be more likely to look like their children. c. the human population could not reproduce. d. children would have more chromosomes.

What are the doorways into and out of cells, attached to the membrane, and built in the rough er.