Answer:
B) Na+
Explanation: Na+ molecule is polar, oxygen and carbon dioxide are nonpolar molecules. The cell membrane is a <em>phospholipid bilayer</em> made up of lipid molecules with polar and nonpolar ends. Since it is a bilayer, two phospholipid layers are arranged, one on the other in such a way that one faces the back of the other. The non polar ends are away from outside and inside of the cell, while the polar ends faces towards all the molecules inside and outside the cell.
Since polar-polar molecules repel each other, Na+ can't pass through the cell membrane easily. So it uses the proteins attached the cell membrane inside and outside to transport such molecules by using energy in terms of ATP.
Answer: D. The succession of community is completed.
Explanation:
A succession can be define as a series of gradual changes that occur in the biotic community of the ecosystem with respect to the changes that occur in the abiotic or non-living factors with respect to time until the ecosystem attains stability.
A climax community is the community that develops in the end of the ecological succession. It is the stable community which does not require any further change to occur. With the development of the climax community the succession completes.
Answer:
We learned in biology class that every cell in the body has the same DNA. Whether a heart cell, skin cell or muscle cell—they all read from the same genetic blueprint. Now, scientists are learning there is more to the story.
