Biology, Eighth Edition (Raven)

Chapter 25: Evolution of Development

Post Test

Signalling pathways are essential for cell-to-cell communication. If as a result of a mutation, a receptor is produced in a different cell type what would you expect to happen? (p. 491)
A)This may result in homeosis.
B)Nothing would happen.
C)A homeotic phenotype may appear.
D)none of the above
A stop codon appears in the middle of the coding sequence of the CAL gene in Brassica oleracea. Phylogenetic analysis and CAL gene sequence analysis suggests that the stop codon appeared after the ancestors of broccoli and cauliflower diverged from the other subspecies but before broccoli and cauliflower diverged from each other. What would you predict the phenotype of broccoli to be if the stop codon had only appeared in cauliflower? (p. 492)
A)cannot tell
B)no different
C)It would have fewer, simple flowers.
D)It would have no flowers.
E)It would grow to be very large.
The transcription factor Tbx5, found in humans and birds, is involved in forelimb development. What would occur if you were able to substitute Tbx5 from birds into a developing human embryo? (p. 494)
A)The human would develop wings.
B)No forelimbs would develop.
C)The human would develop short arms.
D)The human would develop arms as normal.
E)none of the above
The CYC gene in snapdragons and other plants is responsible for bilateral symmetry of the flower. How do you account for plants that have the CYC gene and a bilaterally symmetrical ancestor, but have radial symmetry? (p. 495 - 496)
A)Other genes are involved that "override" the CYC gene.
B)This is a mutant form of the gene that now causes radial symmetry.
C)The CYC gene has lost its function.
D)none of the above
Transgenic plants were used to test the hypothesis that the AP3 gene plays an important role in petal formation. Various forms of the AP3 gene were added to ap3 mutant Arabidopsis. What did this experiment conclude? (p. 497)
A)AP3 does not play an important role in petal development.
B)The 3' end of the gene has a sequence that is crucial for petal formation.
C)The 5' end of the gene has a sequence that is crucial for petal formation.
D)The central part of the gene has a sequence that is crucial for petal formation.
Why is it not possible to infer the function of a gene if it has an almost identical sequence to one with a known function in another species? (p. 497)
A)It is possible.
B)There may be interaction with other genes.
C)It may be have become an inactive pseudogene.
D)a and b
E)none of the above
The eyes of a vertebrate, an insect, a Mollusc and a Planarian are very different in construction. This morphological evidence suggests that the eye evolved independently at least twenty times. However, molecular analysis has shown that a gene homologous to the Pax6 gene in the mouse is found almost universally in the animal kingdom and plays a role in lens formation in taxa from ribbon worms to fish. This suggests that the initiation of the eye may have evolved only once. Why is the molecular evidence more compelling than the morphological evidence? (p. 500)
A)it is not; eyes did evolve independently
B)it has great similarity in DNA sequence among widely different organisms
C)it functions in the same role in each case
D)transgenic experiments have shown that the Pax6 gene from different organisms are functionally equivalent
E)b, c & d
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