Chapter 24 13-03-03 1:59 PM
alternation of generations: the regular alternation of mode of
reproduction in the life cycle of an organism, such as the alternation
between diploid (sporophyte) and haploid (gametophyte) phases in plants.
Sporophyte: an individual of the diploid generation produced through
fertilization in organisms that undergo alternations of generations; it
produces haploid spores.
Gametophyte: an individual of the haploid generation produced when a
spore germinates and grows directly by mitotic divisions in organisms that
under go alternation of generations.
Poikilohydric: having little control over internal water content. P 550
Xylem: the plant vascular tissue that distributes water and nutrients.
Phloem: the food conducting tissue of a vascular plant.
Ovule: in plants, the structure in a carpel in which female gametophyte
develops and fertilization takes place.
Seed: the structure that forms when an ovule matures after a pollen grain
reaches it and a sperm fertilizes the egg
Coevolution: the evolution of genetically based, reciprocal adaptations in
two or more species that interact closely in the same ecological setting
List the defining characteristics of land plants, and how these
characteristics are different from those found in other eukaryotic
They are eukaryotes
Almost all are photoautotrophs
Have cell walls
All are sessile (stationary)
No terrestrial animals are sessile, but some aquatic ones are
Has a very different life cycle than animals (alternation of generations)
Explain the basic pattern of the plant life cycle, and the steps
involved (see Fig 24.1)
1. meiosis produces spores (plant produces haploid seed)
2. spores germinate, it divides by mitosis to produce multicellular haploid
gametophyte (baby haploid plant) 3. gametophytes give rise to haploid gametes (baby plant makes ovule and
4. fertilization of gametes occurs
5. a zygote is produced and develops the plant into a “sporophyte” and the
zygote produces seeds.
7. produces spores through meiosis.
Explain the evidence in support of the hypothesis that land plants
and charophytes shar