STUDY GUIDE FOR MIDTERM EXAM #2
The following study guide should provide you with a fairly comprehensive overview of what to focus on for the exam. Note, however, that this is not a comprehensive or exclusive study guide. Anything that appeared in the lectures is fair game on the exam. This will help guide your studying but cannot replace your review of the lecture handouts and your own notes. Also, please consult the glossary that is already on-line for you. This study guide will not repeat those definitions, and you will be expected to know them.
The exam will cover everything that has been covered in lecture since the first midterm examination. The exam will cover material presented in lecture. Material presented in the textbook but NOT in lecture will not be covered on the examination. However, the background reading may help you understand, or reinforce your understanding of lecture material. The chapters covered in this exam are 29 (introduction to plants and early plant evolution), 30 (the evolution of seed plants), 35 (plant structure and function), 36 (transport in plants), and 38 (the angiosperm life cycle). Note that we will cover plant control and plant hormones (chapter 39) in midterm #3.
You can see examples of last year's examination here.
- The evolution of plants began largely with the colonization of land 475mya in the Ordovician and is largely a story of adaptations to terrestriality. Understand these adaptations and challenges. Be able to contrast the challenges with the advantages of moving onto land.
- Understand the evidence for the charophyte green algae being the sister taxon to plants, also understand the unique characteristics that differentiate plants from charophytes.
- Understand the evolutionary shifts that came with the evolution of plants:
- Life history:
- Alternation of generations:
- Heteromorphic gametophyte/sporophyte generations
- Shift of dominance from gametophyte to sporophyte
- Replacement of flagellated sperm by pollen
- Vascular tissue
- Angiosperm: fruit and flower
- In the context of the phylogeny, recognize the evolutionary sequence of adaptations that permitted increased terrestriality and how each of these adaptations serve as a synapomorphy to define nested clades. You should know these adaptations and the clades that they define:
- Recognize that there are competing hypotheses as to whether or not these form a monophyletic group.
- Recognize the defining characters and why they live in the environments that they do.
- Understand the common characteristics and know what the following terms apply to: gametophyte, antheridium, archegonium, zygote, embryo, sporophyte.
- Know the three different taxa (and defining characters) and a stereotyped life cycle:
Seedless vascular plants: Lycophytes & Pterophytes
- Know the key points of their evolution and their general macroevolutionary history.
- Understand why these are true vascular plants.
- Recognize what heterospory is and know what megaspores and microspores are.
- Know that these are NOT a monophyletic group. Lycophytes are the sister taxon of Pterophytes + Spermatophytes.
Lycophyta: Know some of the fossil history of this group and that sporangia are born on sporophylls.
Pterophyta: This is the sister taxon to Spermatophyta. This clade (Pterophyta + Spermatophyta) have the synapomorphy of megaphyll leaves and roots that can branch.
- Recognize defining traits of horsetails, true ferns, and whiskferns. Know the generalized life cycle:
- Increasing dominance of sporophyte, but gametophyte still free-living.
- Dominance during the Carboniferous
Seed plants ( = Spermatophyta) composed of two clades: Gymnosperms + Angiosperms
- Gametophyte highly reduced and dependent on sporophyte.
- Fertilization by pollen, not mobile sperm.
Recognize how these play out in the gymnosperm life cycle:
Understand the macroevolutionary history and how these evolutionary trends relate to increasing aridity.
Know the four divisions of gymnosperms:
- Cycads: know defining traits and insect pollination (convergent with angiosperms)
- Gingkos: know defining traits, fossil relict status
- Gnetophytes: know defining traits, three living lineages, possession of vessel elements. For the latter, be able to consider what the implications are for the evolution of vessel elements if vessel elements are homologous or homoplasious with angiosperm vessel elements. Consider this whether the above phylogeny is correct or if perhaps gnetophytes are sister to angiosperms...
- Conifers: know defining traits, overview of diversity
The flower and the fruit--why are they so important in the success of the angiosperms?
Know the general aspects:
- refined vascular tissue
- vessel elements
- fleshy ovary protecting the seed
Two interdependent systems: roots & shoots
- Know the different kinds of roots and some of the structural adaptations
- Know the general terms for describing the shoot system, including what apical dominance is
- Know what the different modified stems are
- Know the parts of the leaf and know how they differ:
- arrangement: alternate, opposite, whorled
- margins: entire, lobate, serrate
- venation: palmate, parallel, pinnate
- division: simple, compound, bicompound
- modifications: tendrils, defense, storage, asexual reproduction, bracts, insectivory
- Know the different parts of the flower and their origins as leaves
- Distinguish between perfect and imperfect flowers, and monoecious and dioecious plants
Know the evolutionary trends in floral evolution:
- reduction in parts
- radial to bilateral symmetry
- superior to inferior ovary
Be able to contrast monocots and dicots. Know the differences. Including the fact that monocots are monophyletic and the traits that define them are therefore apomorphies for the clade. Know that "dicots" are paraphyletic and therefore the traits that define them are plesiomorphic for the different clades that make up "dicots".
Know why indetermine growth and developmental plasticity are so important for a plant. Know the different kinds of life forms that are found amongst the plants
- herbaceous vs woody
The Angiosperm Life Cycle
Understand the development of the female gametophyte, including the formation of the embryo sac, the distribution of haploid nuclei in the embryo sac, and the egg cell, synergid cells, antipodal cells, and polar nuclei.
Understand the development of the male gametophyte (pollen grain).
Know what biotic and abiotic pollination are. Know mechanisms for avoiding self-pollination.
Understand DOUBLE FERTILIZATION and why it is adaptive.
Understand seed development, how this relates to double fertilization, and how three generations contribute to the seed structure.
Why are fruits adaptive? How is fruit ripening and color change related to this? What are adaptations for fruit dispersal?
Know the difference between simple, aggregate, and multiple fruits.
Understand the basic mechanics of seed germination.
Asexual reproduction: be able to contrast fragmentation and apomixis. Do not confuse these with self-fertilization.
Plant tissues & growth
Know the different plant cell types, where they are found, and their unique characteristics: parenchyma; collenchyma; sclerenchyma, tracheids & vessel elements; sieve-tube members & companion cells.
Know how these are organized into three tissue systems and that these are continuous throughout the entire plant: dermal tissue, ground tissue, vascular tissue.
Know that indeterminate growth occurs in meristematic tissue: apical meristems generate primary growth (length); lateral meristems (vascular cambium & cork cambium) generate secondary growth (girth).
Know the basics of primary growth in both roots and shoots. How are they interconnected? How are they similar? How do they differ?
Know the basics of secondary growth
Transport in plants
Know the basic three levels of plant transport:
- Individual cells via passive diffusion and active transport
- Short distance via apoplastic, symplastic, and transmembrane routes
- Long distance via xylem and phloem
Have a strong understanding of how water moves upward via uptake in the roots, transport in the xylem, and transpiration out of the stomata. Understand how water flows to more negative water potential gradients and how this relates to the transpiration-cohesion-tension theory of water movement in xylem.
Have a good understanding of stomata regulation and different adaptations that plants have due to the transpiration/photosynthesis tradeoff.
Have a strong understanding of how solutes move in phloem via the bulk flow hypothesis
Examples from last year's examination
The following questions are from last year's second examination that covered this material. Answers are intentionally NOT included for you. You will need to be confident enough in your understanding of the material to be confident in your answer.
I. Evolution of terrestriality in plants:
A. What are three challenges that the ancestors of plants faced in colonizing the terrestrial environment? You may want to read part B below before answering this question.
B. What is an adaptation that allowed plants to face each of the three challenges that you list above? This can be a major feature found throughout plant evolution (i.e. it does not necessarily have to be a synapomorphy for land plants).
C. What are three advantages that the earliest ancestors of plants would have had by colonizing land?
D. Approximately when did plants first colonize land (you can give an approximate date or a geological time period)?
II. Use the phylogeny below to answer this section
Which taxa are indicated by the letters in the above phylogeny?
Insert the following key features in the evolution of plants in the phylogeny above (you need only insert the number). If a trait has evolved twice, make sure that you include both. Two characters are given for you.
3. Insect pollination
4. Gametophyte generation entirely dependent on sporophyte generation
5. Phragmoplastic cytokinesis
6. Heteromorphic haploid/diploid generations
7. Vessel elements (non-moss)
10. Roots that can branch
11. Cellulose in cell wall
13. Sporangia encased in sori
14. True vascular tissue
15. Single cotyledon
III. Compare and contrast:
A. Heterosporous vs. Homosporous
B. Monoecious vs. Dioecious
IV. Spermatophyte Life Cycles: For the following questions, match the various structures of seed plants with the proper sex and generation (A—D) that most directly produces them. (7 points)
A) male gametophyte
B) female gametophyte
C) male sporophyte
D) female sporophyte
1. Scale of ovulate (ovule-bearing) pinecone ____________
2. Integument of pine seed ____________
3. Egg cell in the embryo sac ____________
4. Fruit ____________
5. Pollen tube ____________
6. Microspores of pollen cones ____________
7. Megasporangium of pine ovules ____________
V. Water flows through a plant quite differently than how sap flows through a plant. Please read all of the following before beginning to answer. Do not repeat your answers between questions.
A. Contrast the mechanism by which water and sap flow through a plant.
B. The mechanisms above create fundamental differences in the direction that water and sap flow through the plant. In terms of seasons, one it one of these fundamental differences?
VI. Multiple Choice:
1. The following are all true about the life cycle of mosses except
- external water is required for fertilization.
- flagellated sperm are produced.
- antheridia and archegonia are produced by gametophytes.
- the gametophyte generation is dominant.
- the growing embryo gives rise to the gametophyte.
2. You are hiking in a forest and happen upon a plant featuring a central stemlike structure from which sprout many, tiny, leaflike structures. Which of these would be the most certain means of distinguishing whether it was a true moss, or a club moss (Phylum Lycophyta)?
- its color
- its height
- if seeds are present
- if conducting tissues are present
- the appearance of its spore-producing structures
3. A botanist discovers a new species of land plant with a dominant sporophyte, chlorophylls a and b, and cell walls made of cellulose. In assigning this plant to a phylum, which of the following, if present, would be least useful?
- sperm that lack flagella
4. How have fruits contributed to the success of angiosperms?
- by nourishing the plants that make them
- by facilitating dispersal of seeds
- by attracting insects to the pollen inside
- by producing sperm and eggs inside a protective coat
- by producing triploid cells via double fertilization
5. Which of the following correctly describes a perfect flower?
- It has no sepals.
- It has fused carpels.
- It is on a dioecious plant.
- It has no endosperm.
- It has both stamens and carpels.