A plant anatomist investigates the nutritive seed tissue of a pine tree (gymnosperm) and a sunflower (angiosperm). Which of the following statements accurately compares the origin and ploidy level of the nutritive tissue in their mature seeds?
- The nutritive tissue of the gymnosperm is haploid () and develops from the female gametophyte before fertilization, whereas that of the angiosperm is triploid () and forms after double fertilization.Answer
- BThe nutritive tissue in both gymnosperms and angiosperms is triploid () because both seed plant groups undergo double fertilization inside enclosed ovary walls.
- CThe nutritive tissue of the gymnosperm is diploid () produced by xylem translocation of manufactured sugars, whereas that of the angiosperm is haploid () derived from phloem storage.
- DThe gymnosperm nutritive tissue is triploid () formed as an architectural adaptation for anemophily, whereas the angiosperm nutritive tissue is diploid () formed to attract entomophilous vectors.
Answer
The nutritive tissue of the gymnosperm is haploid () and develops from the female gametophyte before fertilization, whereas that of the angiosperm is triploid () and forms after double fertilization.
In gymnosperms, the nutritive tissue (endosperm) is formed directly from the haploid () female gametophyte prior to fertilization. In angiosperms, double fertilization takes place: one sperm nucleus fertilizes the egg cell to form a diploid () zygote, while the second sperm nucleus () fuses with the two polar nuclei () of the central cell to produce a triploid () primary endosperm nucleus, which develops into triploid endosperm tissue.
Step-by-Step Solution
Key Concept
Differences in seed nutritive tissue ploidy and double fertilization between Gymnosperms and Angiosperms