Question

Which is the most likely result if the Ubx gene was activated either before or after it normally is activated in the sequence of Hox gene expression?
A. The insect develops slightly shorter or longer abdominal legs.

B. The insect develops normal body parts at either a slower or more rapid rate.

C. The insect develops normal body parts but in an altered time sequence.

D. The insect develops legs in other parts of its body.

Answer 1

Answer:

D. The insect develops legs in other parts of its body.

Explanation:

HOX genes, also known as homeotic genes, are evolutionarily conserved genes (containing homeobox sequences) that encode master regulators of embryonic development in animals. Hox genes modulate the body plan of an embryo along the head-tail axis. In general, these genes are arranged in the same order as they are transcriptionally expressed along the anteroposterior body axis. Moreover, Ultrabithorax (Ubx) is a Hox gene that is responsible for the proper development of the third thoracic segment in insects. In Drosophila, it has been shown that different segments of the leg regulate their size in response to Ubx expression.