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6.7 Floral Organ Development — Test 1
Q1. According to the ABC model, the four floral whorls from outside in are specified by:✓ A (sepals), A+B (petals), B+C (stamens), C (carpels)
Q2. A-class activity alone (whorl 1) specifies:✓ Sepals
Q3. The combination of A + B class activity (whorl 2) specifies:✓ Petals
Q4. The combination of B + C class activity (whorl 3) specifies:✓ Stamens
Q5. C-class activity alone (whorl 4) specifies:✓ Carpels
Q6. A-class and C-class genes are mutually antagonistic, meaning that:✓ Each represses the other; loss of one lets the other spread across all whorls
Q7. In an apetala2 (A-class) loss-of-function mutant, C spreads to all whorls, giving the pattern:✓ Carpel-stamen-stamen-carpel
Q8. In an agamous (C-class) loss-of-function mutant, A spreads to all whorls and the flower becomes:✓ Indeterminate, with repeating sepal-petal-petal whorls ('flower within a flower')
Q9. In an apetala3/pistillata (B-class) loss-of-function mutant, the flower has the pattern:✓ Sepal-sepal-carpel-carpel
Q10. Which floral homeotic gene does NOT encode a MADS-box transcription factor?✓ APETALA2 (AP2)
Q11. SEPALLATA (SEP) genes are needed (with ABC genes) to specify:✓ Petals, stamens and carpels (they are the 'E' function)
Q12. The fact that ABCE proteins act together in multi-protein complexes is described by the:✓ Quartet model of floral organ specification
6.7 Floral Organ Development — Test 2
Q13. Organ-identity (homeotic) gene mutations in flowers cause:✓ Organs to form in the wrong positions (one organ replaced by another)
Q14. The C-class gene AGAMOUS has two roles: specifying carpels/stamens and:✓ Conferring determinacy (terminating the floral meristem)
Q15. In the ABC model, B-class genes (AP3/PI) act in which whorls?✓ Whorls 2 and 3 (petals and stamens)
Q16. If a flower shows sepal-sepal-carpel-carpel, the defective gene class is:✓ B-class
Q17. The floral organ-identity genes were originally discovered as:✓ Floral homeotic mutants (organs in wrong positions)
Q18. The 'floral quartet' for petal identity would include A-class, B-class and which other proteins?✓ E-class (SEPALLATA) proteins
Q19. A homeotic transformation in which stamens are replaced by petals would result from:✓ Loss of C-class activity (allowing A to spread into whorl 3)
Q20. In most angiosperms, if the perianth is not differentiated into sepals and petals, the organs are called:✓ Tepals
Q21. The ABC(E) model is a powerful example in plant biology because it shows how:✓ Combinatorial gene expression specifies distinct organ identities
Q22. The floral meristem, unlike the vegetative meristem, is determinate because:✓ AGAMOUS represses WUS, so the meristem is used up making the flower
Q23. Overall, floral organ development demonstrates that homeotic (identity) genes in plants, like those in animals, work by:✓ Assigning identity to a structure according to its position