Drosophila Mutations Such as Bcd, If Homozygous in the Mother

question 43

Multiple Choice

Drosophila mutations such as bcd, if homozygous in the mother, produce offspring with lethal defects, no matter what the genotype of the offspring. For some other genes, the mutant phenotype can be "rescued" by introducing a wild- type allele into the embryo. What is the reason for these different outcomes?

• A) Non- rescuable mutations are of paternal origin.
• B) bcd is a Hox gene.
• C) Rescuable mutations act as dominants.
• D) Rescue requires recombination between the maternal and introduced alleles.
• E) bcd is a maternal effect mutation.

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Definitions:

Hornworts

A group of non-vascular plants belonging to the division Anthocerotophyta, characterized by a horn-like structure which is the sporophyte growing from a flat, green thallus.

Alternation of Generations

A type of life cycle characteristic of plants and a few algae and fungi in which they spend part of their life in a multicellular n gametophyte stage and part in a multicellular 2n sporophyte stage.

Gametophyte

The reproductive stage in the life cycle of plants and algae where gametes, the cells responsible for reproduction, are created.

Sporophyte

The diploid multicellular stage in the life cycle of plants and algae that produces spores through meiotic division.