Unlike adults, infants alternate between short waking periods and short naps. what can we infer about their neurotransmitters?

During the first one to two months of life, infants are incapable of deep sleep (they do not have trouble falling asleep but they do not generally stay asleep for very long stretches). This happens because infants can’t make the difference between night and day - they do not yet have a circadian rhythm. Around six weeks, the hormone melatonin is produced (pineal gland) and it helps establish a normal sleep-wake cycle.

Explanation:

The internal clock system in a newly born baby is not synchronized  with the 24 hour clock system of the real world and thus most of the newly born babies hardly sleep more than  4 hour at a time. The Circadian rhythms of  a fetus is synchronized with the mother's  heart rate and breathing when he/she is in womb. After birth a child has to develop its own circadian rhythms when exposed to sunlight and night frequently but this process takes time.

many phylogenetic trees have a single lineage at the base representing a common ancestor. a lineage that evolved early from the root and remains unbranched is called basal taxon. when two lineages stem from the same branch point, they are called sister taxa.

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explanation:

sex cells are usually half's then they find another half and make a fertilize egg