Question

chickens do not have teeth, but they do have the genetic code for teeth buried in their dna. scientists studying genetics have been able to create chicken embryos with developing tooth buds. these incipient tooth buds are comparable to those found in crocodiles at a similar stage in embryo development. which of the following most likely enabled scientists to grow these toothed - chickens? a the genes regulating the development in tooth buds can be turned on artificially in a laboratory. b tooth buds from crocodile embryos can be removed and successfully grafted into the mouths of chicken embryos. c the genes for the development of tooth buds can be removed and inserted into chicken dna. d tooth buds often grow in chicken embryos naturally and then are reabsorbed at the embryo develops.

Explanation:

The problem states that chickens have the genetic code for teeth in their DNA. Option A makes sense because if the genes regulating tooth - bud development can be artificially turned on in a lab (using genetic manipulation techniques), it would explain how scientists created chicken embryos with developing tooth buds. Option B is about grafting crocodile tooth buds, but the text emphasizes the chicken's own genetic code. Option C is incorrect as the text says the genes are already in chicken DNA (not inserted from another source). Option D is wrong because the text implies that the tooth - bud development in the experiment was an artificial manipulation, not a natural process that is usually reabsorbed.

Answer:

A. The genes regulating the development in tooth buds can be turned on artificially in a laboratory.