Week 5 Study Guide
Big-picture topic —
Explain the sequential adaptations to life on dry land illustrated in the rise of plants, and
culminating in the most successful group, the angiosperms.
(A) Discuss traits important to survival of the adult stage, including transport tissues and
organs, adaptations that allow gas exchange while preventing water loss, and the
switch to a dominant and independent sporophyte stage in the life cycle.
(B) Discuss traits involved in reproduction, including (a) the feature that freed plants
from their early dependency on environmental water for fertilization;
(b) heterospory; (c) seeds; (d) double fertilization and nourishment of the developing
embryo; (e) flowers and fruit, and how they allow symbiosis with animals that
improves pollen transfer and seed dispersal
Gymnosperms —
Understand the following themes in plant evolution (be able to provide examples):
- progressive reduction of gametophyte and dominance of sporophyte
- improved vascular tissues allowing growth to greater heights above ground
- greater protection of reproductive parts
- pollen (immature male gametophyte) replaces swimming sperm
Understand how the seed develops from the ovule, and be able to define these terms
Know the basic life cycle of the pine tree. Where does meiosis occur? What is the
multicellular haploid stage(s)?
Understand adaptations that that enable conifers to survive in drought (= dry conditions),
including tough needle-like leaves with dense tissues, thick cuticles, recessed stomata
What is inefficient about the way most gymnosperms transfer their pollen to the female cones
of other plants?
What is a sporophyll? What part of a gymnosperm is the sporophyll? What part on an
angiosperm is the sporophyll?
Angiosperms —
Know that angiosperms replaced gymnosperms as the dominant land plant group around 65
million years ago at the end of the Mesozoic Era, following a mass extinction event.
Explain the key differences between angiosperms and gymnosperms, including:
- flowers vs. cones
- naked seeds vs. seeds enclosed in fruit
- improved transport tissues (e.g. xylem with vessel elements)
- role of animals in pollination and seed dispersal
Be able to define flower and fruit and understand their basic parts, and where they fit in the
life cycle.
Understand the angiosperm life cycle; be able to explain double fertilization
Be able to provide examples of heterotrophic (parasitic or carnivorous) angiosperms
Understand the concepts of symbiosis and coevolution as they apply to angiosperms,
animals, and fungi. In particular, understand that many angiosperms have mutualistic
relationships with (1) mycorrhizal fungi, and (2) animal pollinators and fruit dispersers.
Be able to give examples of pollination syndromes that illustrate (1) mutualism between
plant and animal, (2) exploitation of the animal partner by the plant.
How do angiosperms protect themselves from competitors and from herbivores?
How does coevolution contribute to biodiversity -- meaning why does it tend to increase the
overall number of species present in an ecosystem over time?
Be able to explain the economic and ecological importance of angiosperms, and the human
uses for plant defensive chemicals
Terms to know -Angiosperm
Flower
Fruit
Pericarp
Ovule
Seed
Tracheid
Vessel elements
Pollination syndromes
Double fertilization
Pollen
Sporophyll