Tutor profile: Megan M.

What characteristics cause deep water in the ocean to circulate?

Deep ocean water circulates through 1.) salt and 2.) heat. This is called thermohaline circulation (thermo-meaning temperature) and (haline - referring to salt). Differences in saltiness of the water and heat of water determine where it will be in the water column. Salty, cold water is more dense and therefore sinks to the bottom whereas fresher, warmer water is less dense and moves to the top. This is how ocean circulation occurs and this affects Earth's climate! There are some really cool videos online that show this process using water tanks.

What is the difference between r and k selected organisms?

R selected organisms have lots of offspring that do not require a lot of energy to produce. K selected organisms tend to have few offspring that are energy intensive. Examples of R selected organisms are mice, bacteria, weeds, and insects whereas K selected are elephants, humans, and whales.

Why do antibiotics not work for viruses?

Antibiotics do not work for viruses because of structural differences between bacteria and viruses. Antibiotics work by targeting structures within bacteria (usually the cell wall, cell structures that make DNA and RNA, or structures that make proteins). This is how antibiotics can stop the bacteria from growing or kill the bacteria. However, viruses have different structures from bacteria. Viruses have only DNA or RNA and a protein coat, which is different than the structures bacteria has. Because of those differences, the targets antibiotics use aren't available and can't stop or kill the virus. This is why if you have the flu, you shouldn't take antibiotics!