Dr. Travis E. Huxman

• CV

ECOL 182 (Spring) Intoductory Biology - 2008 Study Guide Exam Three

I've written this after having completed the questions for the exam, and while looking at the lecture notes - this is a guide for studying, not necessarily a content list that you should memorize.

It will look a lot like the old study guide, but I've carefully changed the components that relate to this year's class.

Evolution of photoautotrophy

The goal of this section was to provide you with 'a modern view' of photosynthesis, including: (1) where did it come from? (2) what is the primary stucture? (3) what does variation in the structure mean? (4) where are physiological processes controlled?, and (5) how does the system integrate into a plant.

We discussed such issues as:

When photosynthesis likely evolved and it's distribution in lifes clades
The likely number of times photosynthesis evolved
Where oxygenation abilities evolved (where means, 'where in the diversity of life')
The universal photosynthetic structure, including important variation on the theme (Halobacteria, etc)
The 'problem' of chlorophyll biosynthesis (relationship between biosynthetic pathways and evolutionary relationships)
The relationship of chloroplasts and mitochondria to prokaryotes and eukaryotes
The relationship between the Calvin Cycle and the Light Reactions (processes in the Universal Photosynthetic Structure), including the concept of "sink" control over rates of photosynthesis.
The energetic requirements in the Calvin Cycle (does Rubisco activity need energy?)
How photosynthesis is regulated at the membrane, chloroplast, cell, leaf and whole plant level.
The nature of carbohydrate feedbacks on photosynthetic rate.

Evolution and diversity in plants (I)

The goal of this section was to introduce you to the initial variation in the most ancient groups of plants and contrast groups as we moved through the evolutionary tree. We started with talking about how plants have special features that maintain or add variation in a population (Fisher's fundamental theorem of evolution by natural selection). We ended by discussing the synapomorphies and important evolutionary innovation through time for different clades.

We discussed such issues as:

What is a plant?
What ways are plants different than animals (traits that they possess and mechanisms they have for introducing genetic variability, etc.)
What is an embryophyte and how is it different from algae?
What is a tracheophyte (versus a non-tracheophyte)?
What is the alteration of generations that is important in embryophytes?
How did the pattern of alteration of generations change in the evolution of plants?
What are characteristics that allow for invasion of the land?
How do ancient plants move resources around their bodies?
When did stomata evolve?
What is the difference between phloem and xylem?

Evolution and diversity in plants (II)

The goal of this section was to continue with the description of the variation in the more derived groups of plants and contrast groups as we moved through the evolutionary tree. Important contrasts here included differences between non-seed and seed plants, and differences between gymnosperms and angiosperms. We also talked about evolutionary trends across all groups (such as the relationship between sporophytes and gametophytes).

We discussed such issues as:

Differences between heterosporous and homosporous plants
What is so cool about a 'seed'? Is a seed just a fancy zygote?
What is double fertilization?
The characteristics (morphological and physiological) associated with the production of secondary growth (e.g., meristem types, etc).
The arrangement of xylem trachieds and sieve tube elements (in gymnosperms)

Plant structure and function (I)

Once we finished talking about the Angiosperms, we started discussing how plants function. Much of this was in the context of the unique characteristics of the Angiosperms (as compared to Gymnosperms and other groups). We spent a whole lot of time talking about how water moves in plants.

We discussed such issues as:

The differences between trachieds and vessel elements
Changes in phloem in Angiosperms
Synapomorphies of Angiosperms (including Monocots and Eudicots)
How water moves in plants as a function of variation in solute and pressure potentials (between cells and within whole plants and to the atmosphere)
The role of stomata in controlling the evaporative loss of water and balancing carbon dioxide uptake.
How when substantial tension develops, a break-down of the continuous stream of water from the roots to the shoots, leaves and atmosphere occurs. This constrains where (what types of environments on earth) plants can grow.

Plant structure and function (II)

In the last lecture I provided, we picked up on the topic of cavitation, and important differences between plants groups (angiosperms, gymnosperms) and plants with different vascular characteristics (trachieds, vessel elements, pit densities). I introduced the concept of 'safety margins', that illustrated how risky plants behave as a function of their environment. We then began a discussion of how plants grow, and what constrains their maximal height. We discussed then, at length, how substances move in the xylem and phloem, before we began discussing nutrients.

We discussed such issues as:

Dessication induced cavitation versus freez-thaw induced cavitation (and their interaction).
The importance of the maintenance of turgor for growth (cells grow by maintaining positive pressure that can expand cell walls)
How gravity influences the components of water potential
What keeps big trees from getting bigger?
The source-sink concept and translocation of materials in the phloem
The pressure flow model of transport (interactions between xylem and phloem)
Where are nutrients located, and where do most come from in terrestrial ecosystems (note! This will be from the notes that we didn't cover......you should remember what I told you in class about those notes.....)