Final answer:
In the hot geysers of Yellowstone National Park, thermophiles and hyperthermophiles, which can grow at nearly boiling temperatures, are expected to be found. Archaea and photosynthetic bacteria are examples of extremophiles thriving in these conditions.
Step-by-step explanation:
In hot geysers like those found in Yellowstone National Park, one would expect to find extremophiles known as thermophiles and hyperthermophiles. These types of organisms are adapted to living in extremely hot environments such as hot springs, geysers, and the areas near volcanoes. Thermophiles can thrive in temperatures that are close to 100°C, which is the boiling point of water. Particularly in the Grand Prismatic Spring, a variety of microbial life is supported at high temperatures, including mats of photosynthetic bacteria that give the spring its distinctive colors due to their sunlight-absorbing abilities.
The discovery of archaea in the 1970s shed light on organisms capable of growing in such scorching conditions. In Yellowstone's hot springs, bacteria can also harness chemical energy, combining hydrogen with other chemicals and oxygen to sustain life even at temperatures approaching boiling. Some of the thermophiles in these environments are even capable of surviving at temperatures as high as 122°C, under pressures where water does not boil.