Q25 - Maternal-Effect Inheritance of Snail Shell Coiling
In snail, the direction of cleavage, and therefore the snail shell coiling, is controlled by a single gene, in which the right-coiling allele, D, is dominant to the left-coiling allele, d. Below table shows the results of a set of mating experiment.
Figure 1.
Using the information and data, determine which of the statements are true or which are false.
A. The direction of cleavage is determined by the genotype of the developing snail.
B. If the egg cytoplasm of a recessive homozygous right-coiling mother is injected into the eggs of the "dd" mother, the resulting embryos coil to the left.
C. Injection of the egg cytoplasm from a heterozygous left-coiling mother into the eggs of the right coiling heterozygous mother, does not affect the right-coiling in the embryos.
D. "DD" or "Dd" mothers place a coiling determinant factor inside the egg cytoplasm.
Question reproduced from IBO 2018, Theoretical Paper 2, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)