The mass extinctions that occurred 250 million years ago and 65 million years ago may have been due to gradual process or Catastrophic events.
Answer:
The correct option is: <em>a deficiency of dopamine in the substantia nigra.</em>
Explanation:
The substantia nigra is the principal site involved in the physiopathology of Parkinson´s disease.
Cells from this area degenerate and die progressively causing important degeneration in the central nervous system. The cells that die -with no known reason- are those that produce dopamine and proportionate dopaminergic innervation to the encephalon. In fact, almost all the symptoms exhibited by patients with the disease can be explained by the lack of dopamine in the substantia nigra.
This area uses the neurotransmitter to communicate neurons from the base ganglia. Ganglia are responsible of modulating and modifying movements.
The nigrostriatal system participates in planning and automatic execution of learned movements. When the ganglia activity decreases, so it does the amount and velocity of movements, something typical of the disease.
Answer:
b. behavioral isolation
Explanation:
It is a type of reproductive barrier that can lead to speciation. Behavioral behavior, such as mating rituals as in when two populations of the same species show some difference in behavior, typically in mating rituals
and signals.
Answer:
It's B
Explanation:
Law of independent assortment stated that individual heredity factors assort independently during gamete production. the evidence that Mendel find that supported his law of independent assortment is : different traits are passed on independently of each other
