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.
<span>The formation of the fertilization envelope (slow-block to polyspermy) requires an increase in the availability of </span>calcium ions.
Slow-block to polyspermy is also called cortical reaction. In this reaction, the sperm will be permanently blocked by cortical granules. The release of calcium ion will trigger this reaction.
Dominance involves one allele masking another at the same locus whereas epistasis involves one locus masking a different locus.
Explanation:
Epistasis is a type of gene interaction in which one gene masks or modifies the expression of another gene at a distinct locus.
Dominance refers to the gene interaction in which one allele of a given gene masks the expression of another alllele of same gene.
The comparison of dominance and epistasis give the following information:
- Dominance involves allelic suppression while epistasis involves non-allelic suppression.
- Dominance involves a single pair of alleles while epistasis involves two pairs of allele.
- In dominance, the expression of recessive allele is suppressed while in epistasis, either recessive or dominant non allele is suppressed.
- The effect of dominance is due to the dominant allele while epistasis may be due to dominant or recessive allele.
Both parents must be carriers, which means they have the heterozygous gene (one uppercase letter & one lower case letter). They will still carry that mutated gene (because they have a lower case letter), and their offspring will have a 25% chance of getting a recessive disorder. The percentage is low but still possible.
<span>Independent variable: Time plants are watered (ex. 8am, 12pm, 4pm, 8pm, 12am)
Dependent variable: growth of the plant
Controlled variable: 1. same type plants, 2. same amount of sunlight, 3. same type of dirt, 4. same type of water, 5. same amount of water (each are self explanatory of how to control)</span>
