The right answer is Calcium
99% of the calcium is located in the bone, ensuring the skeletal strength and the hardness of the teeth.
In children and adolescents, it promotes bone growth; in young adults, it participates in the maintenance of bone capital; in the elderly, it contributes to the prevention of osteoporosis.
Beside the bone, calcium has other functions like blood coagulation, muscle contraction, nerve conduction, activation of certain enzymes.
Adequate calcium intake - consistent with the recommended dietary intakes - would have a preventive effect against high blood pressure.
two hydrogen bonds are formed between adenine and thymine
Answer:
la selección natural es el mecanismo principal por el cual la evolución ocurre
Explanation:
Charles Darwin fue un naturalista inglés que propuso la teoría de la evolución o 'descendencia con modificación' mediante el mecanismo de selección natural. Acorde a esta teoría, la selección natural se define como el mecanismo selectivo de reproducción diferencial de los individuos mejor adaptados a su ambiente. La variabilidad es el la materia prima sobre la cual la selección natural actúa, seleccionado aquellos individuos que presentan combinaciones fenotípicas y genotípicas más adaptadas para sobrevivir en un ambiente en particular. Los individuos de una población que son 'superiores adaptativamente' poseen más chances de sobrevivir y reproducirse, y por lo tanto tienen también más probabilidades de transmitir sus genes a la siguiente generación.
Indirect methods like mark and recapture become a strong tool to estimate population size or density in species on which it is impossible to apply a direct methods. <em>Because of their biological and ecological characteristics, the Gypsy moth and the Green lizard populations are good examples for which mark and recapture would work well.</em>
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There are different methods to study population density. There are direct methods and indirect methods. Among these last ones, we might find the Mark-Recapture technique.
The Mark-Recapture technique assumes that
- <em>the population is closed during the sampling season, there is no mortality nor natality, </em>
- <em>marks in the individual last the whole sampling season, and they do not affect the marked individual or their behavior. </em>
- <em>marked individuals are randomly distributed in the population, and </em>
- <em>all the individuals have the same probability of being sampled.</em>
The method consists of capturing a sample of individuals belonging to the population under study. After capturing the individuals, the researcher marks and releases them again. The third step is to sample again: The researcher captures new individuals and counts how many of them are marked. These marked individuals belong to the first sample.
Indirect methods like this become a strong tool to estimate population size or density in species on which it is impossible to apply a direct method such as <em>counting individuals</em>.
For instance, if we need to estimate insects population density (<u><em>Gypsy moth population</em></u>) or reptiles population density (<u><em>Green lizard population</em></u>) because of their biological and ecological characteristics, the best way of doing it is by applying indirect methods. <em>These species characterize as small-sized, fast to escape, they can hide in small inaccessible places, they have nocturnal habits, their reproductive rate is too high, and their distribution rate is wide. </em>Among many other characteristics, their population density can not be estimated by direct methods. Mark-Recapture technique is the most suitable one.
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