Answer: A. The wave carries molecules of air away from the source of the sound .
Explanation:
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:
A Mutation is when a DNA gene is damaged or changed in a way that changes the genetic message carried by that gene.
Explanation:Mutations are sometimes good and sometimes bad it can also cause genetic variation which increases the survival of a species
Answer:
Option (e).
Explanation:
Meiosis may be defined as the process of cell division in which a single parent cell divides into four daughter cells. The chromosome number reduces to half in meiosis.
Crossing over is the process of exchange of genetic material between the homologous chromosomes of the non-sister chromatids. Crossing over will bring variation in the gametes. Hence, the absence of crossing over results in the formation of gametes with less genetic variation.
Thus, the correct answer is option (e).
Answer:
The reactants for photosynthesis are light energy, water, carbon dioxide and chlorophyll, while the products are glucose (sugar), oxygen and water.
Explanation:
Water and carbon dioxide are reactants for photosynthesis. Chlorophyll captures sun's light energy and then plants chemically combine this with water and carbon dioxide to make glucose (sugar) and oxygen.
