Answer and Explanation :
When we begin to move, the brain first sends a signal to the spinal cord, then nerve cells in the spinal cord control the precise coordination of the muscles. The results also indicate that each part of the brainstem controls a certain aspect of moving—either running or walking.
<span>a. an element is a substance that cannot be broken down</span>
One of the reasons why the fish population remains approximately the same from one generation to the next is because not all the eggs laid will survive to adulthood. There are several factors which bring about elimination of the the newly hatched eggs. Examples of these are predators and diseases which eliminate the young offsprings at different stages before they develop into adulthood.
Secondly, production of many eggs by the different fish species leads to competition for survival. Resources such as water, food, oxygen and shelter have to be fought for and its only the fittests that will be able to survive till the reproduction stage.
Answer:
Oxygen levels stay above 15 percent starting 200 million years ago
Explanation:
Atmospheric oxygen levels are related to the evolution on Earth and changes in geochemical cycles that involve climate variations.
The presence of O
2 and evolution of oxygen gave new opportunities to the life on Earth. Oxygen levels in atmosphere have fluctuated between 15% and 35% of atmospheric volume, since the start of the Cambrian period.
So, form the starting 200 million years ago, oxygen level stay above 15 percent and the correct option is "B".
Answer:
Movement.
Reproduction.
Respiration.
Responsiveness.
Excretion.
Adaptation.
All organisms have nucleic acid as the hereditary molecule.
All organisms show adaptation, which occurs at the individual level and is tightly related to homeostasis.
