Answer:
This allele has not been eliminated by natural selection because it may confer an adaptive advantage for particular environmental conditions
Mice and rats are opportunistic species. These species can rapidly adapt to different environmental conditions, while cheetahs are unable to adapt to changing environments.
Explanation:
An allele is a gene variant that may be beneficial, neutral, or deleterious for a particular environment. Different alleles are not eliminated by natural selection against other alleles (even when a priori seem to be deleterious) because they confer a selective advantage in a given environment. For example, the allele for sickle cell anemia is caused by a point mutation which is lethal in homo-zygous individuals, but heterozygous individuals are less likely to die of malaria, thereby this allele has been positively selected in geographic areas where malaria is an endemic disease. Moreover, mice and rats are opportunistic species, i.e., they are species that rapidly adapt to varied living conditions. These species are characterized to have high growth rates and produce many offspring. On the other hand, the cheetah is a highly specialized species that is unable to adapt to changing environments. In consequence, cheetah populations are more prone to become extinct than rat and mice populations.
When neuroscientists employ the term "nucleus", they are usually referring to:_____.
a. a cluster of glial cells in the dorsal-medial CNS.
b. a neural unit composed of anatomically and functionally related neurons.
c. a group of homologous ganglia located either in the cortex or in the cerebellum.
d. cognitively synchronized clusters of apical dendrites anywhere in the PNS.
Answer:
B. A neural unit composed of anatomically and functionally related neurons.
What is the effect of these currents on Earth's temperatures?
Ocean currents act much like a conveyor belt, transporting warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics. Thus, ocean currents regulate global climate, helping to counteract the uneven distribution of solar radiation reaching Earth's surface.
