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4.3 Segment Polarity & Hox — Test 1
Q1. Homeotic (selector) genes in Drosophila are responsible for:✓ Giving each segment its identity (what structures it forms)
Q2. A mutation in a homeotic gene typically causes:✓ Replacement of one body part by another
Q3. Deletion of the Ultrabithorax (Ubx) gene in Drosophila gives a fly with:✓ Four wings
Q4. When Ultrabithorax is deleted, the third thoracic segment is transformed into a:✓ Second thoracic segment (giving a four-winged fly)
Q5. A dominant Antennapedia mutation in Drosophila causes:✓ The antenna to be replaced by a leg-like structure
Q6. In a dominant Antennapedia mutant, the Antennapedia gene is ectopically expressed in the:✓ Head region
Q7. Antennapedia protein, besides promoting thoracic structures, also:✓ Represses genes (e.g. homothorax) that specify antenna development
Q8. A mutant in which wings are reduced to haltere-like structures is best explained by:✓ Ectopic Ultrabithorax expression in the second thoracic segment
Q9. Engrailed in Drosophila is expressed in and defines the:✓ Posterior compartment of each segment
Q10. Initial expression of wingless and engrailed in Drosophila is activated by the:✓ Pair-rule genes
Q11. Wingless in Drosophila is a:✓ Secreted protein that binds Frizzled receptors on neighbouring cells
4.3 Segment Polarity & Hox — Test 2
Q12. Hedgehog in the Drosophila segment-polarity network binds which receptor on neighbouring cells?✓ Patched
Q13. Continued expression of engrailed and wingless across the segment boundary is maintained by:✓ A reciprocal signalling loop between the engrailed and wingless cells
Q14. If wingless is knocked down (RNAi) in its expressing cells, the ____ compartment of each future segment is affected:✓ Posterior
Q15. The homologue of beta-catenin in Drosophila is:✓ Armadillo
Q16. Gooseberry in Drosophila is an example of which class of segmentation gene?✓ Segment-polarity gene
Q17. Abdominal-A in Drosophila is an example of which class of gene?✓ Homeotic (selector) gene
Q18. The two clusters of homeotic genes in Drosophila are the Antennapedia complex and the:✓ Bithorax complex
Q19. The order of homeotic genes along the chromosome matches the order of the body regions they pattern. This property is called:✓ Colinearity
Q20. Homeotic genes encode transcription factors that share a conserved DNA-binding motif called the:✓ Homeodomain (from the homeobox)
Q21. The change in the state of specification of an imaginal disc to a different disc type is called:✓ Trans-determination
Q22. Imaginal discs in Drosophila are:✓ Groups of cells set aside in the larva that form adult structures at metamorphosis