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6.1 Plant Reproductive Development — Test 1
Q1. Apomixis in plants is best defined as:✓ Seed formation without the union of gametes
Q2. The mature embryo sac (female gametophyte) of a typical angiosperm contains how many cells?✓ Seven cells (with eight nuclei)
Q3. Which structure represents the gametophyte generation in flowering plants?✓ The embryo sac (and pollen grain)
Q4. In double fertilization, one sperm fuses with the egg and the second sperm fuses with the:✓ Central cell (forming the triploid endosperm)
Q5. The product of the central-cell fertilization (the endosperm) is typically:✓ Triploid (3n)
Q6. When the pollen tube enters the embryo sac, the cells that break down to receive the sperm are the:✓ Synergids
Q7. The development of a sporophyte directly from gametophytic tissue without gamete fusion is called:✓ Apogamy
Q8. Autogamy in flowering plants refers to:✓ Self-pollination of a flower
Q9. Dichogamy, a mechanism to avoid self-pollination, is the:✓ Maturation of anthers and stigma at different times
Q10. Herkogamy (e.g. distyly, with two style lengths in a species) avoids selfing by:✓ Spatially separating the anthers and stigma
Q11. In gametophytic self-incompatibility (e.g. in Solanaceae), the female style produces an S-RNase that:✓ Degrades ribosomal RNA in incompatible pollen tubes, arresting their growth
Q12. In sporophytic self-incompatibility (e.g. Brassica), the primary recognition is the interaction between the stigma receptor SRK and the pollen ligand:✓ SCR/SP11
6.1 Plant Reproductive Development — Test 2
Q13. In most angiosperms, the megaspore mother cell undergoes meiosis to form four megaspores, of which:✓ Only one survives and forms the embryo sac
Q14. The female gametophyte (embryo sac) is:✓ Haploid
Q15. After meiosis in angiosperm reproduction, the haploid spores produce gametes by:✓ A few mitotic divisions to build the gametophyte
Q16. In sporophytic apomixis (adventive embryony), the embryo develops from:✓ Somatic nucellar or integument cells, keeping the maternal genotype
Q17. Gametophytic apomixis involves an altered meiosis (apomeiosis) so that the female gametophyte is:✓ Unreduced (diploid), giving a clonal embryo
Q18. In diplospory, the megaspore mother cell:✓ Fails to complete reduction, giving an unreduced gametophyte
Q19. Pseudogamy in apomictic plants refers to the situation where:✓ The endosperm still needs fertilization although the embryo forms without it
Q20. A major reason apomixis is of agricultural interest is that it could:✓ Fix hybrid vigour, maintaining elite genotypes over generations
Q21. During double fertilization, both male gametes are delivered to the embryo sac by:✓ A single pollen tube that ruptures in a degenerated synergid
Q22. The two sperm cells of an angiosperm are produced when the generative cell of the pollen:✓ Divides by mitosis (after the asymmetric pollen division)
Q23. The vegetative (tube) cell of the pollen grain functions to:✓ Form the pollen tube that delivers the sperm
Q24. Self-incompatibility systems are important in plants because they:✓ Promote outcrossing and maintain genetic diversity