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4.2 Drosophila D–V Axis — Test 1
Q1. The dorsal–ventral axis of the Drosophila embryo is controlled by the nuclear localisation of which protein?✓ Dorsal
Q2. In Drosophila, nuclear Dorsal protein is found on which side of the embryo?✓ The ventral side
Q3. The highest nuclear concentration of Dorsal protein specifies the:✓ Mesoderm (most ventral)
Q4. Although Dorsal protein is present throughout the syncytial blastoderm, it acts as a morphogen because it:✓ Enters nuclei only on the ventral side, forming a nuclear gradient
Q5. Dorsal protein is held in the cytoplasm by which inhibitor until a ventral signal is received?✓ Cactus
Q6. A dorsal mutant (loss of Dorsal protein function) in Drosophila results in:✓ Dorsalization of the ventral side
Q7. In Drosophila D-V patterning, the default fate (where Dorsal stays out of the nucleus) is the:✓ Dorsal fate
Q8. D-V patterning in Drosophila is regulated by preventing the entry into nuclei (on the dorsal side) of which factor?✓ The Dorsal transcription factor
Q9. Gurken protein in the Drosophila oocyte signals the overlying follicle cells to adopt the:✓ Dorsal fate
Q10. Torpedo, the receptor for Gurken, is expressed in the:✓ Follicle cells surrounding the oocyte
Q11. Germ-line chimera experiments showed that the Drosophila D-V axis depends on the ____ contribution of Torpedo:✓ Maternal (ovary/follicle)
Q12. Wild-type Drosophila eggs developing in a Torpedo-deficient ovary produce ____ embryos:✓ Ventralized
Q13. On the ventral side of the embryo, a protease cascade leads ultimately to:✓ Entry of Dorsal into the nuclei of ventral cells
Q14. The Drosophila Toll receptor, activated on the ventral side, ultimately causes:✓ Degradation of Cactus, releasing Dorsal to enter nuclei
Q15. Which best summarises the logic of Drosophila D-V patterning?✓ A ventral signal lets Dorsal enter nuclei, specifying ventral fates by a nuclear gradient