Sarah is finishing a model drawing of a cell. She adds a membrane to the nucleus on her model. The nucleus of a cell has a membrane that isolates material inside of it from the rest of the cell. Why does the nucleus need a membrane?
A.
The membrane helps the nucleus to create energy for the cell.
B.
The membrane helps the nucleus to create proteins for the cell.
C.
The membranes helps the nucleus to remove waste from the cell.
D.
The membrane helps the nucleus protect genetic material for the cell.

For the strategies below, decide whether they are best described as demand-side solutions or supply-side solutions to meeting human needs for fresh water. remember that a demand-side solution reduces demand for fresh water, whereas a supply-side solution increases the supply of fresh water. (a) damming a river to create a reservoir (b) desalinating seawater (c) a nation invading a neighboring country to access their rivers (d) raising water prices for consumers and businesses (e) providing tax breaks for companies that use less water (f) replacing inefficient irrigation with more-efficient drip irrigation to grow crops (g) requiring low-flow showerheads in all new homes