Answer:
silica
Explanation:
Diatoms are microscopic organisms. they have shell that is made from organic compounds and silica.Diatoms contain silica in their cell walls. This material is used industrially in the production of toothpastes, silver polishes, and swimming pool filters. Silica is used to remove stains and debris.
99% of calcium is found inside the cells of the body.
One reason is because the short days and long nights prevent the earth from warming up, another reason could be because the sun's rays in winter are more spread out thus minimizing the amount of energy
It is true that rivers and streams are biodiverse ecosystems that are sensitive to change. Details about rivers and streams can be found below.
<h3>What is river and stream?</h3>
A river is a large and often winding stream which drains a land mass, carrying water down from higher areas to a lower point, oftentimes ending in another body of water, such as an ocean or in an inland sea.
On the other hand, a stream is a small river or a body of moving water confined by banks.
Rivers and streams are both freshwater ecosystems, hence, tend to respond to changes in their environment caused by anthropogenic activities.
Therefore, it is true that rivers and streams are biodiverse ecosystems that are sensitive to change.
Learn more about rivers and streams at: brainly.com/question/10904801
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The correct choice is velocity=distance/time of v=d/t
