Complete question:
In a separate study, 68 rock pocket mice were collected from four different, widely separated areas of dark lava rock. One collecting site was in Sonora, Mexico. The other three were in Chihuahua, Mexico. Dr. Nachman and colleagues observed no significant differences in the color of the rocks in the four locations sampled. However, the dark-colored mice from the three Chihuahua locations were slightly darker than the dark-colored mice from the Sonora population. The entire Mc1r gene was sequenced in all 68 of the mice collected. The mutations responsible for the dark fur color in the Sonora mice were absent from the three different populations of Chihuahua mice. No Mc1r mutations were associated with dark fur color in the Chihuahua populations. These findings suggest that adaptive dark coloration has occurred at least twice in the rock pocket mouse and that these similar phenotypic changes have different genetic bases.
How does this study support the concept that natural selection is not random?
Answer:
The study supports the concept that natural selection is not random because in different areas with the same or very similar environmental characteristics, the same phenotype was produced by different types of mutations.
Explanation:
All of the sampled animals are inhabiting dark substrate. Probably animals needed to camouflage to survive. Natural selection must have driven them to produce dark color, similar to the substrate color. So animals from the different regions suffered different mutations that drove them to have almost the same dark fur color. The environmental condition is favoring the same phenotype.
The point at which the sun crosses the <span>equator to make night and day the same length during the second time of the year is an equinox.</span>
Blood flows through an artery that is partially blocked. as the blood moves from the wider region into the narrow region, alternately increases and then decreases.
<h3>What is the purpose of blood flow in heart?</h3>
The removal of positive charge by electrochemical gradients causes the membrane potential of the cell to shift more strongly in the direction of the equilibrium potential for potassium.
The membrane would become more negative as potassium permeability through the membrane increased. Given that potassium is a positively-charged ion and that the intracellular environment has a net negative charge, enhancing the membrane's permeability would result in a more negative membrane.
For instance, the amplitude of the potassium concentration gradient across the myocyte decreases as the external potassium level rises, lowering the resting membrane potential.
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Answer:
In biology, a gene is a basic unit of heredity and a sequence of nucleotides in DNA or RNA that encodes the synthesis of a gene product, either RNA or protein. During gene expression, the DNA is first copied into RNA.
Euchromatin is a lightly packed form of chromatin that is enriched in genes, and is often under active transcription. Euchromatin comprises the most active portion of the genome within the cell nucleus. 92% of the human genome is euchromatic.
The genes present in heterochromatin are usually inactive. The genes present in euchromatin are either already active or will be active during growth. Heterochromatin is transcriptionally-inactive. Euchromatin is transcriptionally. (This one here is the difference)
