WINTER SCIENCE A Magazine to explore Science in the news and improve science skills.
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Weird place on Earth Mono Lake in eastern California is where researchers found a type of bacteria that appears to break the rules for how we think life should survive. Credit: NASA image gallery
Like poison for phosphorus You may not know phosphorus when you By Stephen Ornes / December 13, 2010 see it, but your body does. Phosphorus is a sturdy workhorse element. In DNA molecules, phosphorus helps support the Reading for Information whole double helix. Within cells, energy Is an important skill. shows up as ATP — and the “P” stands for phosphorus (specifically, phosphate, a 1. Underline important form of phosphorus). ideas. All life as we know it, in other words, depends on phosphorus. For that reason, 2. Highlight vocabulary scientists around the world were shocked terms. December 2 when a team of scientists announced finding life forms that didn’t 3. Write test questions necessarily depend on this all-important with answers. element. In laboratory tests, the scientists grew bacteria that were able to use 4. Do further research. arsenic — a different element with similar chemistry — in the place of phosphorus. It’s a surprising discovery because living Questions: organisms have never been found without all six of the ingredients crucial to life: 1. carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur (all together known as CHNOPS). Arsenic, though, is a 2. potentially fatal poison. Many scientists say they would like to see more evidence that the research team did 3. in fact observe life forms using arsenic instead of phosphorus. “This is an amazing result, a striking, very 4. important and astonishing result — if true,” Alan Schwartz told Science News. Schwartz researches chemistry at 5. Radboud University Nijmegen in the Netherlands. “I’m even more skeptical than usual, because of the implications. 6. But it is fascinating work.” The bacteria came from Mono Lake, a lake in eastern California that is well 7. known for its unusual population of living organisms, including shrimp and algae. The lake doesn’t drain, so the only way for 8. water to leave is through evaporation. As a result, the lake is much saltier than
the ocean.
Several researchers had been studying a number of tiny organisms that lived in Mono Lake mud. Astrobiologists study life in the universe and want to know how it started, how it has changed, and what will happen to life in the future. They also want to know whether life exists on other planets and if so, what it might look like. Many Astrobiologists study what lives in Earth’s strangest places, such as Mono Lake, as a way to understand the possibilities for life. The study was led by Felisa Wolfe-Simon of NASA’s Astrobiology Institute and the U.S. Geological Survey in Menlo Park, Calif. She and her team removed organisms from the Mono samples and grew those bacteria in the lab. The scientists fed the microbes with sugar and vitamins — but left out phosphate. Then they changed the diet again, and gave the microbes arsenate, which is a form of arsenic. In one type of bacteria, called GFAJ-1, the researchers observed that arsenic wasn’t fatal. The bacteria continued to grow, though not as fast as if they’d had phosphorus. After studying these bacteria, Wolfe-Simon and her team concluded that the organisms had begun to make use of the arsenic the way they usually used phosphorus. The researchers suggest that arsenic was being used as a building block in the bacteria’s DNA. “This microbe, if we are correct, has solved the challenge of being alive in a different way,” WolfeSimon told Science News. If the scientists are right, then “life as we know it” may not include all the life that actually is possible. For astrobiologists, that conclusion suggests that life on other planets may not necessarily look like life on Earth. It’s possible that follow-up studies will show that the researchers were mistaken. Wolfe-Simon and her team could not get rid of all the phosphorus when they were growing the bacteria. Some scientists say minute amounts might be enough to keep the microbes alive. It’s possible that, in the experiment, the bacterium GFAJ-1 was still getting small amounts of phosphate. Can life exist using poison instead of phosphorus? Life of a different type is an exciting prospect, so stay tuned to see how the scientific community reacts. Next up, scientists will want to see how arsenic substitution works.
POWER WORDS arsenic A highly poisonous metallic element having three allotropic forms, yellow, black and gray, of which the brittle, crystalline gray is the most common. Used in insecticides. phosphorus A highly reactive, nonmetallic element occurring naturally in phosphates. DNA A nucleic acid that carries the genetic information in the cell. DNA consists of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the bases. molecule A group of like or of different atoms held together by chemical forces. microbe A minute life form; a microorganism, especially a bacterium that causes disease. bacterium A life form that is a single cell and too small to see without using a microscope. Bacteria (plural of bacterium) live in almost every environment on Earth, including very cold places, very warm places, in all types of water, in the air, even on and in plants and animals. These microorganisms can also cause disease in plants and animals.
Questions: 1. 2. 3. 4. 5. 6.
Name the planets in order. Make a plan: 1. What materials do you need? 2. What is the order of the planets? 3. How are you going to display this information? 4. Make a table of measurements that you need? Object
Sun
Size of object
Distance of object from the sun
Create a scale model of the Solar system. Use cm or mm instead of meters.
Interpreting Charts
Metric Conversions
Science Vocabulary Match the following: 1. Concept ___ 2. Observe ___ 3. Compare ___ 4. Contrast ___ ___ 5. record
a. b. c. d. e.
Science Review Natural gas Coal
Write down or save Find similarities Find differences Idea watch
List each of these under the correct column to indicate which are renewable resources and which are nonrenewable resources.
wind oil hydro electric
Renewable 1. _____________ 2. _____________ 3. _____________
Research List the Main elements In the Earth’s crust.
100 cm = ___ m 1000 m = ___ Km ____mL = 1 L 5000 g = ___ Kg
solar energy geothermal
Nonrenewable 1. ______________ 2. ______________ 3. ______________
Reading Comprehension Zoology is the study of animals. Zoology dates back more than 2.300 years, to ancient Greece. There, the philosopher Aristotle observed and theorized about animal behavior. About 200 years later, Galen, a Greek physician, began dissecting and experimenting with animals. However, there were few advances in zoology until the 1700’s and 1800’s. During this period, the Swedish naturalist Carolus Linnaeus developed a classification system for plants and animals, and British naturalist Charles Darwin published his theory of evolution by natural selection.
Questions to reading: According to the passage, when did major advances in Zoology begin? a. about 2,300 years ago b. about 2,100 years ago c. during the 1700’s and 1800’s d. only during recent history Which of the following is a possible meaning of the word naturalist, as used in the passage? a. a scientist who studies plants and animals b. a scientist who studies animals c. a scientist who studies theory d. a scientist who studies animal behavior 3. Which of the following is the best title for this passage? a. Greek Zoology b. Modern Zoology c. The origins of Zoology d. Zoology in the 1700’s and 1800’s
Standardized Test Practice 1. The steps of scientific methods a. Must all be used in every scientific investigation. b. Must always be used in the same order. c. Often start with a question. d. Always result in the development of a theory. 2. In a controlled experiment, A control group is compared with one or more experimental groups. a. There are at least two variables. b. All factors should be different. c. A variable is not needed. 3. Which of the following tools is best for measuring 100 mL of water? a. 10 mL graduated cylinder b. 150 mL graduated cylinder c. 250 mL beaker d. 500 mL beaker 4. Which of the following is not an SI unit? a. Meter b. foot c. liter d. kilogram 5. A pencil is 14 cm. How many mm long is it? a. 1.4 b. 140 c. 1,400 d. 1,400,000