Over the past several decades, NASA has been sending missions into outer space t
ID: 69236 • Letter: O
Question
Over the past several decades, NASA has been sending missions into outer space to explore our solar system, and to assess the habitability of nearby planets. In 1976, the NASA Viking Mars landers discovered that the soil on Mars contain carbon-based chemical building blocks. These organic compounds could have come from non-biological or biological sources. What if these Mars landers discover life on Mars? Would we be able to recognize it as life? The landers can perform several small scale experiments on the isolated specimen. Analyze the results on page 1 of your handout. In your small groups you will interpret the experimental results and draw your own conclusions. The lander inoculated several sterile culture dishes with Martian soil. A white-film soon formed on the surface of each culture dish. The while-film resembles a dry crust and can be scraped off and transferred into a new sterile culture dish. Once transferred, the white-film quickly coats the new dish. The specimens were exposed to a variety of stress tests. Extreme temperature shifts (between -60C to 20C) had little to no impact on growth rate (white-film production). However, extreme heat (above the temperature ranges found on the surface of Mars) significantly inhibited growth. Radiation exposure caused specimen growth to completely cease. Under the microscope, specimens appear round (coccoid) in shape, with an average diameter between 0.2-0.5 mm. In your lab groups fill out the Table 1 below, including what can (and cannot) be concluded from each experiment (What do the resulst of each experiment mean relative to the hypothesis?). Finally, conclude whether all the evidence support, or contradict the hypothesis that the specimens are indeed biotic. Based on the accumulated evidence, do you think the hypothesis-the specimens are biotic-is supported? Then formulate an argument to support your conclusion.Explanation / Answer
1. White film production: Since the martian soil produced this white film we can assume that some organisms are making this white film. Since, it is reproducible in other culture dishes, we can say that it is a living organism.
2. Heat Resistance: The film production is a sign of the growth of the organism. When exposed to excess heat above the conditions seen on Mars, the growth was inhibited.This shows that these organisms have a wide growth range. So since it is inhibited above the growth range, we can say it is living.
3. Radiation: Radiation is usually used for sterilization. So if growth is inhibited in the presence of radiation, then it means that the organism is living.
4. Appearance: The appearance looks like bacterial cocci. So we can say that the organism is living and showing similar characteristics to bacteria.
Yes, these organisms are living as they show characterisitcs of living organisms:
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