Based on the results of the 2000 study, how should the portion of the tree extending from branch point 7 be altered?

Answer : Option B) Mainland brown bear , ABC brown bear and Polar bear.

Explanation : Based o the results of 2000 study, mitochondrial cytochrome gene b of 61 brown bears from two sites in Alaska. Of which one population of brown bears lives on the coastal mainland of Alaska, and a separate population lives on the ABC islands in southeastern Alaska. This states that the brown bear are of same origin but lives in different place.

But the study revealed that both the brown bears have unique genes hence they have a different origin and can be considered as a different species.

when the researchers compared the sequences of the two clades of Alaskan brown bears with 55 polar bears. Many differences were observed between three of them. This clarifies that it can be considered as a different species for all three of the bears.

answer; ///(b) it is composed of four protein chains and four heme groups;