Diatoms have cell walls composed of
a. silicon dioxide
b. carbon dioxide
c. chitin

There is a liquid capsule inside a cup full of liquid. the cup full of liquid has salt in it and the liquid capsule has no salt in it. in which direction will the solvent flow? a. the salt does not have to move b. from the capsule to the larger cup c. equally between the capsule and the cup d. from the larger cup to the capsule

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

How do the sperm cells get from the stigma to the ovules?