Q44 — Macromutations and Morphogenesis — A1/A2/M Gene Model
One possible genetic cause of changes in morphogenesis is macromutations, which alter gene expression. In the hypothesis diagrammed below: A1 and A2 are independent genes that, through synthesis of substances 1 and 2, control morphogenetic processes 11 and 22 respectively; M is a modifying gene, and A2 is only active when gene M is expressed.
Using the information and diagram, determine whether the following statements are true or false:
A. If the expression of the A2 gene in the phenotype is not possible, only the 11 morphogenetic process will take place.
B. Product 1 can determine if 11 and 22 morphogenetic reactions take place and determine the diversity of morphogenetic processes by interacting with product 2.
C. In the case of a loss-of-function mutation in the modifier gene M, reactions 11 and 22 can occur simultaneously, in which case intermediate morphogenetic processes will take place.
D. Mutation of a modifying gene can regulate the course of morphogenesis and can be considered a molecular-genetic mechanism of speciation.
Question reproduced from IBO 2022, Theoretical Paper 1, licensed under CC BY-NC-SA 4.0 — attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)