Crossing over is essential for the normal segregation of chromosomes during meiosis. Crossing over also accounts for genetic variation, because due to the swapping of genetic material during crossing over, the chromatids held together by the centromere are no longer identical.
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Serotonin and n<span>orepinephrine.
Serotonin decreases appetite by activating </span>5-HT2C receptors<span> on dopamine-producing cells which will cause dopamine release to stop. Dopamine is responsible for the increase of appetite, therefore, serotonin decreases appetite.
Norepinephrine by increasing the production of glucose it also causes the body to feel satiety and, therefore, decreases the appetite.</span>
The answer is 3
Synthesize enzymes from organic molecules