Bio 202: Exam #2

What is sporopollenin? Why is it important? {Ans: A layer of a durable polymer that prevents exposed zygotes from drying out. This adaptation allowed Charophytes to survive outside of watery environments, furthering the potential for a move onto land}What are some key traits of Red Algae? {Ans: Reddish due to photosynthetic pigment phycoerythrin, can absorb deeply penetrating blue and green light, and reproduce sexually with no flagellated gametes}What are extreme halophiles? {Ans: Archaea that live in highly saline environments, some simply tolerate while others require it}What are companion cells? {Ans: Non-conducting cells connected to sieve tube elements that have all the necessary organelles to carry out metabolic functions that help serve sieve tube members and overall function}Nitrogen is essential for production of amino acids in all organisms, however, most nitrogen occurs naturally in forms that are unusable to most organisms. What process solves this dilemma and what are a few ways in which it is carried out? {Ans: Nitrogen fixation is the conversion of atmospheric nitrogen, N2, (or other unusable forms) to Ammonia, NH3 (or other useable forms). Some bacteria actively convert nitrogen, and will therefore form symbiotic relationships with other organisms}What causes phylogenetic trees