A)The organism must have multiple paired appendages along the length of its body

Question

A)The organism must have multiple paired appendages along the length of its body.
B)These genes are fundamental, and are expressed in all cells of the organism.
C)Most of its Hox genes owe their existence to gene fusion events.
D)Its Hox genes cooperate to bring about sexual maturity at the proper stage of development.
E) The organism has the genetic potential to have a relatively complex anatomy.


q2)
Q1) The existence of the phenomenon of exaptation is most closely associated with which of the following observations that natural selection cannot fashion perfect organisms?

A)Adaptations are often compromises.
B)Chance events affect the evolutionary history of populations in environments that can change unpredictably.
C)Evolution is limited by historical constraints.
D)Natural selection and sexual selection can work at cross-purposes to each other.

Explanation / Answer

"1)
A is correct.

B is also correct, although not per definition, most Hox genes are expressed in all cells of the organism.

C is correct.

D is not correct. Hox genes have a lot of functions but sexual maturity is not one of them. Hox genes operate during your development, rarely after that.

E is also correct, though the key-word is potential.

For the second part, everything except D is correct, or highly plausible I would say.


2)
A is wrong because adaptations are irrelevant to natural selection. Adaptations happen in non-germ cells per definition and thus can not be passed on to the next generation. This idea, of evolution being due to selected adaptations, is known today as Lamarckian evolution, which was wrong (as we know, Darwinian evolution was correct).

B is correct, not much to explain here. Take birds as a classic example of exaptation. Feathers were first used to regulate temperature, when this was no longer needed because the environment changed, they could use them to fly (over millions of years off course)

C is not correct. Evolution is in theory unlimited. It may take time and some events are highly implausible but technically, anything within the rules of physics is possible to evolve. However most things that would seem beneficial, like humans with eyes on the back of their head, do not evolve because anything more than the bare limit to make a species survive, is a waist of precious energy in nature.

D is correct but has nothing to do with exaptation.

So for the first part: B"


Source: (Student Biomedical Sciences
http://ph.answers.yahoo.com/question/index?qid=20110320023728AA9hAit)

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