Plant Diversity- Seed Plants

Gymosperms and angiosperms are the "seed plants".

Readings From Textbook

pages 618 - 635.

Gymnosperms

Expected Learning Outcomes

By the end of this course a fully engaged student should be able to

- defne and contrast homospory and heterospory
- discuss the evolutionary advantage of heterosporty over homospory
- identify the parts of a seed and discuss why reproducing by seeds is an advantaged compared to reproducing by spores
- discuss the life cycle of a pine
- discuss the characteristics of pines that are advanced relative to the ferns and those that are primitive relative to the angiosperms

Angiosperms

Expected Learning Outcomes

At the end of the course a fully engaged student should be able to

- discuss the parts of a flower
- discuss the evolutionary advantage of reproducing by flowers rather than by cones
- discuss the life cycle of an angiosperm
- discuss the characteristics of angiosperms that are advanced relative to the pines and those that are primitive relative to the angiosperms
- discuss why angiosperms are the most successful of all plant groups

Plant Diversity- Ferns

Ferns are examples of the first vascular plants.

Readings From Textbook

pages 610 - 617

Expected Learning Outcomes

By the end of this course a fully engaged student should be able to

- discuss the components of the vascular system
- discuss the advantage of a having a vascular system
- diagram the life cycle of a fern
- discuss the morphological and physiological characteristics of ferns
- discuss the characteristics of ferns that makes them considered to be advanced relative to mosses but primitive relative to the gumnosperms
- discuss how the morphological and life history characteristics limits their size and geographic distrubution

Plant Diversity- Algae and Mosses

Plants are interesting to me because they are so different from us and the organisms that we are most familiar with (mostly animals). At first these differences will cause unfamiliarity, but eventually you will not be so bogged down by learning new vocabulary and you will hopefully come to realize that plants are more interesting than you might have thought (and besides, no plants means no dorritos, french fries, or beer?).

Readings From Textbook

pages 600 - 610.

Further Viewing

1) Here is the slideshow that I will use in class for the final three lectures.

http://www.slideshare.net/secret/DBv71wnKTH1YBN

2) Here is a powerpoint presentation from a group called "world of teaching" that covers plant diversity? There are many "quiz questions" that should be helpful to look at.

http://www.worldofteaching.com/powerpoints/biology/Plant%20Divisions.ppt

Primitive Plants

Expected Learning Outcomes

A the end of this course a fully engaged student should be able to

- functionally define a plant
- discuss the characteristics of a primitive plant such as Chlamydomonas
- diagram a life cycle of a human
- diagram the life cycle of Chlamydomonas
- distinguish between oogamy and isogamy
- discuss the evolutionary advantage of multicellularity, diploid dominance, and oogamy

Transition to Land

Expected Learning Outcomes

By the end of this course a fully engaged student should be able to

- discuss the problems plants face when moving to the land
- discuss the characteristics of the ancestor of land plants
- diagram the life cycle of a moss
- discuss the morphological and physiological characteristics of mosses
- discuss the characteristics of mosses that makes them considered to be advanced relative to primitive plants but primitive relative to the ferns
- discuss how the morphological and life history characteristics of mosses limits their growth and geographic distribution

Carbon Fixation

Technically, carbon fixation is defined as the first chemical reaction that incorporates carbon dioxide into an organic molecule (a molecule with more than one carbon atom).

In C3 photosynthesis the following step is considered to be carbon fixation-

carbon dioxide + RuBP ==> PGA

In CAM photosynthesis the following is considered to be carbon fixation-

carbon dioxide ===> malate

Note: CAM plants also have the reaction- carbon dioxide + RuBP ===> PGA, but in this case this step is not considered to be carbon fixation.

Sometimes people will loosely use the term carbon fixation to mean the production of glucose by photosynthesis. Be sure that you are aware of how different authors are using the term and you should attempt to use the term as precisely as possible in your own work.

Expected Learning Outcomes

By the end of this course a fully engaged student should be able to

- define carbon fixation
- identify carbon fixation in C3 and CAM photosynthesis

Factors Influencing the Rate of Photosynthesis

The rate of photosynthesis can be limited by a variety of environmental factors including

1) light
2) concentration of carbon dioxide
3) water
4) soil nutrients

Which factor most limits photosynthesis varies between environments.

Light- Can directly limit the rate of photosythesis by limiting the rate at which ATP and NADPH are produced

Carbon dioxide- can directly limit the rate of photosynthesis by limiting the rate at which the Calvin Cyle takes place

Water- can indirectly limit the rate of photosynthesis. When plants are water stressed they close their stomata (long before the concentration of water in the cell becomes too low for water to supply electrons to P680). Thus, the rate of photosynthesis is water stressed plants is directly limited by the amount of carbon dioxide in the leaf.

Soil Nutrients- Sometimes the rate limiting step in photosynthesis is the rate at which carbon dioxide + RuBP ==> PGA. This reaction is catalyzed by the enzyme RuBP carboxylase. Increasing the amount of RuBP carboxlyase in the cell can increase the rate at which this reaction occurs. Fertilizing plants with nitrogen will increase the amount of RuBP Carboxylase produced by the plant.

Expected Learning Outcomes

By the end of this class a fully engaged student should be able to

- discuss the factors that can directly or indirectly limit the rates of photosynthesis
- discuss how the most limiting factors should vary between environments
- discuss how the activities of farmers such as irrigation and fertilization can increase photosynthetic rates
- interpret the graph at the top of the post (irradiance measures light intensity and the three lines represent different concentrations of carbon dioxide)
- explain what why the graph shows that shape

Cellular Respiration

Cellular respiration converts chemical energy in glucos to chemical energy in ATP which is the ultimate source of energy used to do "biological work".

Readings From Textbook

Pages 163 - 183

Powerpoint Presentation

http://www.slideshare.net/MarkMcGinley/cellular-respiration-11758578

Expected Learning Outcomes

By the end of this course a fully engaged student should be able to

- discus glycolysis, anaerobic respiration, alcohol fermentation, lactic acid fermentation, aerobic respiration, the Kreb's Cycle, and electron transport
- compare and contrast aerobic respiration with anaerobic respiration
- discus why the breakdown of glucose to produce ATP is so much more efficient when oxygen is present
- describe where in the cell the different parts of cellular respiration take place

Why Are Plants Green? or Why Aren't Plants Black?

If I was hired as an engineer to design a machine whose job was to convert light energy into chemical energy I probably would not choose to use a green pigment. Instead, I would choose to use a black pigment because black pigments would absorb more energy because they would absorb all wavelengths of light. If you look at a field of plants you will notice that they are green (OK this doesn't work too well around Lubbock in the winter)and we have learned that chlorophyll, a green pigment, is the dominant photosynthetic pigment. What is going on?

Here is one theory about why chlorophyll is the dominant photosynthetic pigment in plants today. Early on there were photosynthetic bacteria with purple pigments (purple is a combination of red and violet). These aquatic bacteria had a very simple sort of cyclic electron flow that was able to convert light energy into energy in ATP (they didn't have non-cyclic flow or the Calvin Cycle).

Origin of chlorophyll- The purple pigment absorbed all wavelengths of light except for the reds and violets. Thus, any bacteria using purple pigments that lived deeper in the water than the purple bacteria on the surface would have no light to use because it had all been absorbed by the surface bacteris (exploitative competition). Because red and violet wavelengths pass through to deeper water, bacteria that contained a pigment that was able to absorb these wavelengths would be able to coexist with the purple bacteria. This was the origin of chlorophyll.

Competition purple and green photosynthetic pigments. Over time there was competition between organisms with purple photosynthetic pigments and green photosynthetic pigments. Obviously, the green photosynthetic pigments won this competition because chlorophyll is the dominant photosynthetic pigment today (there are still examples of photosynthetic bacteria with purple pigments, but they are limited to very harsh environments). Interestingly, chlorophyll came to dominate, not because it was a better at absorbing light energy, but rather because the cyclic flow machinery associated with chlorophyll was more efficient at producing ATP than the machinery associated with the purple pigment was. Thus, it is an evolutionary accident that modern plants are green.

Black Plants

It would be possible for modern plants to be black if they had enough accessory pigments to allow them to absorb all wavelengths of light. In fact, some red algae that live deep below the surface where light levels are low are basically black. Because the amount of light is not the factor that limits the rate of photosynthesis in most terrestrial plants, it is not worth the cost of producing extra accessory pigments. However, deep in the ocean where light levels are low, plants benefit from being able to absorb all wavelengths of light so deep marine algae have invested in extra accessory pigments.

Expected Learning Outcomes

By the end of this course a fully engaged student should be able to

- discuss why terrestrial plants to not invest in the accessory pigments required to make them black