46. Self-incompatibility in flowering plants is a biochemical recognition and rejection process that
prevents both self-fertilization and self-pollination.
prevents self-pollination and occasionally prevents self-fertilization.
prevents self-fertilization but not self-pollination.
prevents self-pollination but not self-fertilization.
prevents self-fertilization and occasionally prevents self-pollination.
47. When pollen from one species lands on the stigma of a flower from another species
the pollen tube typically does not develop.
the pollen tube typically forms, but the sperm cannot penetrate the egg.
the pollen tube typically forms and grows to the ovary, but then stops.
the pollen tube typically forms, but the sperm are killed.
the pollen tube typically forms and the egg is usually fertilized, but the embryo rarely
grows.
48. Chemical cues that help guide a developing pollen tube toward an ovule are released by the
49. For a typical flowering plant, the first cell of the triploid (3n) endosperm is formed from
one sperm fused with two antipodal cells.
two sperm fused with the egg.
one sperm fused with the central cell.
one sperm fused with the egg.
two sperm fused with a synergid.
50. Unique to flowering plants, the making of an embryo-nourishing ____ is an outcome of double
fertilization.