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1.4 Morphogens — Test 1
Q1. A morphogen is best defined as a:✓ Diffusible signalling molecule that specifies cell fate in a concentration-dependent way
Q2. Proteins or mRNAs that are regionally localised in the unfertilised egg and regulate later development are called:✓ Cytoplasmic determinants
Q3. The 'French flag' model explains how:✓ A morphogen gradient specifies different fates at different concentration thresholds
Q4. Positional information is the idea that a cell:✓ Acquires a 'value' according to its position and differentiates accordingly
Q5. When Drosophila leg cells destined to form the middle segment are placed at the tip of the antenna, by the French-flag logic they:✓ Stay committed as leg cells but form the structure appropriate to the new position (claws)
Q6. Which statement about morphogens is correct?✓ A morphogen can be a paracrine factor produced by one group of cells and acting on another
Q7. Cytoplasmic determinants influence development by being:✓ Unequally distributed to daughter cells during cleavage
Q8. Bicoid protein in the Drosophila embryo acts as a morphogen for the:✓ Anterior–posterior axis
Q9. A threshold response to a morphogen means that:✓ A cell adopts a particular fate only above a certain concentration
Q10. Genomic equivalence implies that pattern formation depends mainly on:✓ Differential gene expression guided by positional cues
Q11. Morphogen gradients are most closely associated with which mode of specification?✓ Conditional specification
Q12. The opposing Bicoid and Nanos gradients in Drosophila together establish the:✓ Anterior–posterior body pattern
Q13. A morphogen differs from a simple signalling molecule because a morphogen:✓ Produces several distinct outcomes depending on its concentration