In your primary post, please write a response of at least 125 wordsto one (1) of the following three (3) bulleted options, using your ownwords. In addition, please make a substantive reply to a fellow studenton any topic.

Discussion Topic 1. The phytoplankton that brought Earth to life.Review the video (Johnson, 2014) about the "phytoplankton that broughtEarth to life" from the link given below, or from the link in theInstructor's Insights area. In this clip, which is under 5 minutes inlength, Penny Chisholm discusses a tiny phytoplankton calledProchlorococcus. Based on that video, please address the following:

• (a) What is the importance of Prochlorococcus for life on the planet Earth, both historically and in the present day?
• (b) Explain what the known geographic variations inProchlorococcus tell us about relationships between organisms and theirenvironments.

Discussion Topic 2. Characteristics of ATP.If you choose this topic for your primary post, you must base your poston the instructor's video about ATP (Cox, 2015). The video can be foundin the Instructor Insights area.

• (a) Describe at least three specific points that the video makes about ATP.
• (b) Explain how this fits with this week’s lessons.
• Please note that I am looking for specific points that are covered in the video, so material gleaned from Wikipedia or other sources may not meet the requirements.

Discussion Topic 3. Chemosynthesis in the Giant Tubeworm. The Giant Tubeworm (Riftia pachyptila)is an animal that lives on the floor of the ocean, near hydrothermalvents that release very hot, chemical-rich water. The adult form of thetubeworm is sessile, which means that it plants itself in oneplace, and doesn’t have any locomotion. Riftia pachyptila has a uniqueway of getting the energy that it needs to stay alive (Deep MarineSciences, 2015; JKM12988, 2016; Kusek, 2007).

• (a) Describe how Riftia pachyptila get its energy.
• (b) Discuss how this relates to this week’s lessons.

References

Cox, J. F. (2015). Four minutes about ATP. . Please see "Instructor's Insights" area for Week 3.

Deep Marine Scenes. (2013). Facts: Giant Tube Worms. [Video]. Retrieved from https://www.youtube.com/watch? v=IddCPTnmj4Q

JKM12988. (2016, December 5). Giant Tube Worms and symbiotic bacteria. [Video]. Retrieved from

Johnson,R. (2014, March 5) The phytoplankton that brought Earth to life. PBSNewshour. Public Broadcasting System. Retrieved from http://video.pbs.org/video/2365193451/

Kusek, K. M. (2007, January 12). Deep-sea tubeworms get versatile 'inside' help. Oceanus Magazine. Retrieved from http://www.whoi.edu/oceanus/feature/deep-sea-tubew…