The biosphere is a. the surface of the Earth, where there is plenty of light and oxygen b. the areas of the Earth where most plants and animals live c. all of the areas on Earth that can sustain life
Microbes that can live in environments without much water, sunlight, or oxygen are called a. eukaryotes b. extremophiles c. eubacteria
The “shadow biosphere” hypothesis suggests that a. life on other planets is probably very similar to life on Earth b. new types of bacteria are evolving very quickly underground c. Earth may contain microbes that have very different chemical structures from us
Discussion/essay questions
Do you believe in life on other planets? Why or why not? Why do you think we haven’t found any?
Transcript
The biosphere is all of the areas on Earth that can sustain life. Most complex plants and animals need lots of water, oxygen, and sunlight to survive. When scientists look for life on other planets, they seek places that have the potential to provide these things. On Earth, however, certain microbes thrive in environments that are low in these essential ingredients. These microbes are called extremophiles. They live in volcanoes, deserts, and Antarctic ice. Some extremophiles survive because they can use unusual chemicals to sustain themselves. It is possible that Earth contains microbes with chemical structures that are very different from our own. This hypothesis is called the “shadow biosphere.” A shadow biosphere would be made up of life that is chemically unrelated to life as we know it. If this type of life exists, there may be more habitable planets than we think.
Fertilizers are very useful for humans. They help us grow enough crops to feed large populations. Do you think that we can prevent eutrophication while continuing to use fertilizers? Why or why not?
Transcript
Eutrophication is a process where a body of water fills up with plant nutrients like nitrogen and phosphorus. This usually happens when rain washes crop fertilizers into a lake. The fertilizers, which use nitrogen to help plants grow, cause excess amounts of algae to grow on the surface of the water. This is called an algal bloom. When the algae die, bacteria use large amounts of oxygen to decompose the plant matter. This process is harmful because it depletes the lake’s oxygen, causing fish at the bottom to suffocate. Eventually, the lack of oxygen can create an aquatic dead zone: a place where little to no aquatic life can survive.
Lake Hillier, a small lake on one of Australia’s , is a famous tourist attraction known for its unusual pink colour. The lake was first discovered in 1802. For years, even scientists were puzzled by the of a pink lake. However, most scientists now agree that the colour is probably caused by an abundance of bacteria. This bacteria doesn’t make the lake – it’s considered to be safe to swim in. In fact, swimming in Lake Hillier would be very effortless. This is because the high concentration of salt in the water would allow a person to easily on the surface. Not many people have been in the lake, though, because it is a protected area, and it’s difficult for the average tourist to access. Most tourists take a helicopter so that they can view the lake from the air.
Comprehension questions
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Discussion/essay questions
A similar lake in Australia, known simply as Pink Lake, was also once a popular tourist attraction. However, it lost its pink colour years ago due to human activities. Do you think this could happen to Lake Hillier? How could this be prevented?
Transcript
Lake Hillier, a small lake on one of Australia’s islands, is a famous tourist attraction known for its unusual pink colour. The lake was first discovered in 1802. For years, even scientists were puzzled by the idea of a pink lake. However, most scientists now agree that the colour is probably caused by an abundance of bacteria. This bacteria doesn’t make the lake unsafe – it’s considered to be safe to swim in. In fact, swimming in Lake Hillier would be very effortless. This is because the high concentration of salt in the water would allow a person to easily float on the surface. Not many people have been in the lake, though, because it is a protected area, and it’s difficult for the average tourist to access. Most tourists take a helicopter tour so that they can view the lake from the air.
Hand washing is one measure you can take to prevent infection from COVID-19. What other precautions are you taking to protect yourself?
Transcript
Washing hands is common practice for maintaining good hygiene and preventing disease. However, studies show that many people still don’t wash their hands properly. Rinsing with water is not enough to eliminate viruses. This is because viruses can adhere to skin, and the friction caused by rubbing hands together is not always enough to remove them. The molecules in hand soap are able to break the virus away from the skin. These molecules can then kill the virus by breaking the bonds that hold it together. It is recommended that people wash their hands for over twenty seconds with soap and water. Drying hands is also important, because wet hands can transfer bacteria to surfaces more easily than dry hands. Some people use hand sanitizer instead of soap to prevent disease. While hand sanitizer can be effective against bacteria and viruses, medical professionals agree that it is not quite as effective as soap and water.
