Question

Use the following information to answer the question 50 and the Extra Credit Question Suzanne Simard and colleagues knew that the same mycorrhizal fungal species could colonize multiple types of trees. They wondered if the same fungal individual would colonize different trees, forming an underground network that potentially could transport carbon and nutrients from one tree to another (S. Simard et al. 1997. Net transfer of carbon between mycorrhizal tree species in the field. Nature 388:579-82). "co, Birch Douglas Firy Pots containing seedlings of three different tree species were set up and grown under natural conditions for three years (Fig. A). Two of the three species (Douglas fir, birch) could form ectomycorrhizal connections with the same fungal species, but the third species (cedar) could not form an ectomycorrhizal connection with the fungal species. In some of the pots, the researchers placed airtight bags over the Douglas fir and birch seedlings and injected carbon dioxide made from carbon-13 Into the bags with the Douglas fir and carbon dioxide made from carbon-14 into the bags with the birch. (13C and 14C are different isotopes of carbon that can be detected and measured by researchers.) As the he Ectomycorrhizo into sugars that could be tracked and measured by the researchers. The researchers measured whether the sugars in each plant contained only the carbon isotope that was in the air of their plastic bag or also the carbon isotope from the air around the other plant. SO) Which of the following results would support Simard et al.'s (1997) hypothesis that fungi can move carbon from one plant to another? (Hypothesis: Sugars made by one plant during through a mycorrhizal fungus and be incorporated into the tissues of another plant.) A) Carbon-14 is found in the birch seedling's tissues and carbon-13 in the Douglas fir. B) Carbon-14 is found in the Douglas fir seedling's tissues and carbon-13 in the birch. C) Either carbon-13 or carbon-14 is found in the fungal tissues. D) Either carbon-13 or carbon-14 is found in the cedar seedling's tissues. 51) EXTRA CREDIT - Referring to Simard et al. (1997), which design element is the control in this experiment and why? A) the bags over the seedlings to contain the different types of carbon dioxide B) the fact that all the seedlings are different species C) the cedar seedling, because it is not bagged D) the cedar seedling, because it does not form ectomycorrhizal connections with the tested fungus

Answer 1

50) Carbon-14 is found in the Douglas fir seedlings tissues and carbon-13 in the birch.

The above experiment was done to prove exchange of carbon between plants through mycorrhizal connections by same species and for this when two different plants were grown with different carbon source Carbon 13 for Douglas fir plants and carbon 14 for birch plants and due to exchange of carbon between plants carbon 13 was seen in birch plants and carbon 14 was seen in Douglas fir plants. This clearly indicates that a clear exchange of carbon happened between two different plants by mycorrhizal connections.

51) the cedar seeding because it does not form ectomycorrhizal connections with tested fungus

The cedar plant acted as control of experiments to differentiate from plants where ectomycorrhizal connections were seen to the plant were no ectomycorrhizal was seen.