Directions: After reading the articles “Photosynthesis reinvented” and “How plants hunt water,” log in to Science News and use the Search page to answer these questions. Make sure you adjust the filters to include articles written before 1999, if the question requires you to do so.
1. The article about Chong Liu mentions that his research is related to the work of Daniel Nocera. Can you find an earlier article about Daniel Nocera’s research?
Possible student response: The article “Hydrogen made using sunlight, cheap materials,” published 9/16/2014, discusses the electrochemical methods Chong Liu later combined with bacteria in his research. As described in “Hydrogen made using sunlight, cheap materials,” photovoltaic, or solar, cells can absorb energy from sunlight and convert it into electricity to power the chemical reaction of splitting water into hydrogen and oxygen using catalysts composed of Earth-abundant elements. When compared to natural biological photosynthesis, the efficiency of Nocera’s system to split water molecules is approximately 10 times higher. There are several other articles about Nocera’s research too; he has been slowly improving his catalysts and his system over the course of many years.
2. Can you find an article about how photosynthesis in plants can help absorb some of the excess carbon dioxide that is now in our atmosphere?
Possible student response: The article “CO2-loving plants can counter human emissions,” published 11/8/2016, discusses how plants can absorb a sizeable fraction of human-produced CO2. Via photosynthesis, plants convert that CO2 into larger carbon-containing molecules stored in the plants. The photosynthetic process in plants is more efficient when CO2 is abundant. While rising CO2 levels had accelerated from a yearly increase of 0.75 parts per million in 1959 to 1.86 parts per million by 1989, between 2002 and 2014 the rate remained relatively stable at around 1.9 parts per million.
3. The article about José Dinneny explained how plant roots can seek out water. Can you find an article that explains how plant roots can attract helpful bacteria and repel harmful bacteria?
Possible student response: The article “Defense hormones guide plant roots’ mix of microbes,” published 7/16/2015, discusses how plant roots produce hormones such as salicylic acid, jasmonic acid and ethylene. These hormones help to attract beneficial bacteria, such as the bacteria involved in nitrogen fixation, a process that converts atmospheric nitrogen into ammonia that plants can use. The hormones also repel harmful bacteria that might prefer to eat the plants or their roots. Plants that were genetically engineered not to produce the hormones had a different and less healthy mix of bacteria growing around their roots.
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