DNA. Deoxyribonucleic acid (DNA<span>) is a nucleic acid that contains the genetic instructions for the development and function of </span>living things<span>. All known cellular life and some viruses contain </span>DNA<span>. The main role of </span>DNA<span> in the cell is the long-term storage of information.</span>
All the populations living and interacting within a particular geographic area make up a biological (or biotic) community. The living organisms in a community together with their nonliving or abiotic environment make up an ecosystem.
The alveoli. These little air sacs are found on the end of the bronchioles and are the place where oxygen enters the blood and the carbon dioxide leaves.
<span>The answer is a certain required chemicals must be actively
transported. Blood brain barrier is a
selective membrane that separates blood circulating from the brain and the
fluid of extracellular in the central nervous system. This is also called a
filtering mechanism, the capillaries that carry blood to the brain and spinal
cord tissue blocking the path way of the certain substance.</span>
Answer:
d. eon, era, period, epoch
Explanation:
The geological time scale has been made so that the scientists can have a practical system about the classification of geological time, thus everything that has happened throughout it. The geological time unites have been defined in accordance with important events that have happened, thus marking their end or beginning. These events can be mass extinctions, catastrophes, climate patterns, domination of certain species etc. The longest of these time units is the eon, lasting for more than half a billion years, and up to 2 billion years. The era comes as the second longest time unit, lasting for several hundred million years. The period lasts for several tens of million years, and the epoch is the smallest unit, lasting for few million years, or several hundred thousand years.
