Trypan blue staining can be used to discriminate between viable and dead cells and determine the number of viable cells present in a cell suspension.
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Answer:
1. Because the drought reduced the number of seeds and finches with bigger beaks were able to eat the larger and harder seeds so more of them survived.
2. Summary: Changes in the size and form of the beak have enabled different species to utilize different food resources such as insects, seeds, nectar from cactus flowers as well as blood from iguanas, all driven by Darwinian selection
3. Medium ground finches with larger beaks could take advantage of alternate food
4. three species of Darwin's tree finches have been known to inhabit Floreana but no birds singing that song on Floreana have been heard in many years.
Explanation:
1. Depth: The water level in the Great Salt Lake fluctuates from year to year. Water levels drop and salinity increases when less water flows into the lake than usual. Not only that, but the wetlands dry up and the shoreline recedes. The reason the shoreline shifts so dramatically is because it sits at the bottom of a broad and relatively flat basin. For a visual example, think of pouring water into a plate versus a bowl.
Salinity: This Great Salt Lake has a high mineral content, as most terminal lakes are, which means that it is quite salty. Even the fresh water flowing into the lake contains small amounts of dissolved minerals. As water evaporates from the lake, the minerals stay behind. As a result, these minerals have accumulated to very high levels because they have been left behind for thousands of years. The Great Salt Lake is between 3.5 and 8 times saltier than the ocean. However, the organisms that survive in such saline conditions have adapted to their surroundings through special features.
Temperature: The Great Salt Lake has a very shallow depth, with an average of 14 feet deep and a mere maximum of 33 feet. This means that a lot of the surface area is exposed to the air, and is at the mercy of its seasonal temperature fluctuations. In the summer, rise to more than 80 degrees Fahrenheit while falling to below freezing in the winter.
2. Depth: Salinity drops and lake levels rise during high precipitation years. Wetlands get covered by salt water, and the shoreline expands, sometimes destroying wildlife habitats and killing sensitive vegetation.
Salinity: <span>Changes in lake elevation are accompanied by changes in salinity. The salinity in the lake decreases as incoming fresh water dilutes the salt water. This happens during the wet years. During dry years, however, salinity increases as continued evaporation removes fresh water.
</span>Temperature: Because of the lake's salt high content, the water doesn't usually freeze. However, as the temperature drops during the winter, less saline zones freeze solid, and most of the lake turns into a vivid pea-soup green color. In mid-March, temperatures begin to rise again as brine shrimp begin hatching. By late April, juvenile, and adult brine shrimp fill the water, serving as food for migrating and breeding birds.
3. Brine shrimp are smaller in highly salty water and larger in less salty water. Also, salinity levels also affect the rate of sexual development. Higher salinities produce adults who reach maturity quicker but are shorter in length. As salinity increases, the abdomen becomes longer relative to body length. Low salinity may also cause cysts to crack prematurely, as well as allowing other competitors into the ecosystem. High salinity results in offspring that develop quickly but are smaller and have a relatively longer abdomen. In short, effects of abiotic conditions on brine shrimp are development rate, the rate of sexual maturity, the overall length of the abdomen, amount/type of food available, cyst density and location.
4. One limiting factor of brine shrimp are predators: corixids that consume brine shrimp, grebes that consume brine shrimp and their cysts, and humans that commercially harvest brine shrimp cysts. Another limiting factor for brine shrimp is cooler temperatures. They<span> are much more productive in warmer water and consume more phytoplankton. However, when the lake water temperature is cold, the shrimp population tends to decline. </span>
In a controlled experiment, an independent variable (the cause) is systematically manipulated and the dependent variable (the effect) is measured; any extraneous variables are controlled. The researcher can operationalize (i.e. define) the variables being studied so they can be objectivity measured.
La mitosis se utiliza para el crecimiento y la reparación y produce células diploides idénticas entre sí y a la célula madre. Se necesitan nuevas células a lo largo de la vida. Estos son para el crecimiento y reemplazo de tejido dañado o desgastado. El cuerpo lo obtiene a través del proceso de mitosis.
