The insect body plan includes many groups of serially repeated units. For example, there are typically three pairs of legs, one on each of the three segments of the thorax. Which of the following options best describes how these pairs of legs develop and
evolve?
A) A single gene controls the development of all six legs. Thus within a species, all three pairs of legs are identical.
B) The leg pairs all influence each other during development. Gene products move by diffusion from one segment to the other. Therefore, it is impossible to alter the development and form of one pair of legs without causing similar changes in the other two pairs of legs.
C) The body parts develop in a modular fashion. Therefore, a genetic change could alter the development of one pair of limbs without noticeably changing the rest of the insect's body plan.
D) The leg pairs grow under the control of an ancient set of highly conserved genes. Therefore, all insects have more or less identical legs. Other parts of the insect body plan can evolve somewhat more freely.
Answer: C
You might also like to view...
Digesting chromatin with a high concentration of DNAse I would yield fragments of what approximate size?
A. 200 B. 400 C. 600 D. 1100
In vascular plants the ________ is larger than the __________
A. diploid sprorophyte; haploid gametophyte B. diploid gametophyte; haploid sporophyte C. haploid sporophyte; diploid gametophyte D. haploid gametophyte; diploid sporophyte
Character displacement makes competing species less similar, which facilitates __________. Fill in the blank(s) with the appropriate word(s)
The most important advantage of sexual
reproduction is related to
a. increased production of offspring. b. avoiding predators. c. avoiding harmful mutations. d. producing offspring identical to the parents. e. the advantage of having two sexes