A stem cell is a cell that has layers of bacteria that helps protect the water that follows through it.
I think it is keystone. If they were not there the population of urchins would go up and the kelp would go down.
Answer:
Epistasis
Explanation:
In epistasis, the interaction between genes is inimical, such that one gene masks or interferes with the expression of another. “Epistasis” is a word coined of Greek roots that mean “standing upon.” The alleles that are being masked or silenced are said to be hypostatic to the epistatic alleles that are doing the masking. The cause of the biochemical basis of epistasis is a genetic pathway in which the expression of one gene is dependent on the function of a gene that precedes or follows it in the pathway.
The example of epistasis given is the pigmentation of mice. we were told that "if a mouse has two recessive alleles for coat color, it is always albino no matter what the genotype of other genes involved in coat color"
Let say recessive allele (rr), it is always albino irrespective of other type of other genes, this is true in the stance that epistasis can be reciprocal such that either gene, when present in the dominant (or recessive) form, expresses the same genotype.
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:
Aggregate fruit is a fruit that develops from several ovaries forming one flower. An example of an aggregate fruit is a raspberry. Multiple fruit is fruit that develops from a cluster of flowers, and each flower produces a fruit, which turns into a mass of a singular fruit. An example of multiple fruit is a pineapple. Each "cube" of a pineapple is a separate fruit formed from a single flower, yet the pineapple as a whole is one mass of pineapple.
