This occurs because REM sleep may provide at least part of the stimulation necessary to correctly develope the immature brain of infants.
REM sleep provides the electrical activity necessary to establish neural connections that include the development of synapses in the brain. These neurological process enables development of sensory, motor, learning and memory system.
Animal cells do not have a cell wall or chloroplasts but plant cells do. This is just one example there are several ways. <span />
The best answers for this question would be:
The songs will become more similar to each other.
<span>The frogs have most likely sync their songs with each other, since the female cannot determine the range of the song of the male frog given the environment that they are living in.</span>
Out of the options I would have to say Penetrating Keratoplasty, I am not sure