What protects the outer layer of all the cells

What are the two causes of density in deep current waters? a. salinity (how much salt) of the water and high temperaturesb. salinity (how much salt) of the water and low temperatures c. oxygen content of the water and high temperatures. d. oxygen content of the water and low temperatures

What type of plant is good for a bioassay and where can i buy it? i only have a month.

Rarefaction is used for which of the following? a. creating a representative sample b. studying how disease impacts populations c. rediscovering species thought to be instinct d. determining which sea creatures live in an area