Download Lecture Notes to Accompany Labs 8 and 9

Lecture Notes to Accompany Labs 8 and 9
The Plant Kingdom Characteristics:
•Nearly all are multi-celled
•Vast majority are photoautotrophs*
–Energy from sun
–Carbon dioxide from air
–Minerals dissolved in water
*Note: I did not mention in class that there are a very few number of plants that do not
photosynthesize but are instead parasites on certain fungi. Even Venus flytraps and other
“carnivorous” plants are primarily photoautrophs. Let me know if you want more information, or
Google mycotrophic plants.
Invading the Land (that is, becoming terrestrial)
•Cyanobacteria were probably the first to spread into and up freshwater streams
•Later, green algae and fungi made the journey together
•Every plant is descended from species of green algae
Adaptations to Land:
•Root systems
•Shoot systems
•Vascular tissues
•Waxy cuticle
•Stomata
Alternation of Generations:
•Sporophyte: Diploid (2N) spore producing body of the plant or algae. Undergoes meiosis to
produce haplod (1N) gametes.
•Gametophyte: The haploid (1N), body in which gametes form during the life cycle via mitosis.
Bryophytes:
•Dominated by gametophyte stage of life cycle
•No vascular tissue
•Has leaf-like, stem-like, and root-like parts
•Usually live in wet habitats
•Flagellated sperm require water to reach eggs
•Only some have cuticle and stomata
•Small – size is limited by lack of vascular system.
Vascular Plants:
•Majority of plants
•Have internal tissues that carry water and solutes
•Two groups
–Seedless vascular plants and seed-bearing vascular plants
Ferns (Pterophyta)
•12,000 species
•Wet, humid habitats; mostly tropical
•Many are “epiphytes”
•Spores on lower surface of fronds
Fungi
•Single or multi-celled eukaryotes
•Heterotrophic
–Decomposers (saprophytes)
–Parasites
Fungal Life Cycle
•No motile stage
•Asexual and sexual spores produced
•Spores germinate after dispersal
•In multi-celled species, spores give rise to a new mycelium
Fungal spores
•Withstand extreme conditions of dryness, heat or cold.
•Disperse by animals, wind or water to distant locations.
•Remain dormant until environmental conditions favor germination
•Fungal classification is based on type of sexual spores
Lichen
•Combination of fungus and photosynthetic algae
•Organisms are symbionts: Fungal mycobiont + photosynthetic photobiont
Fungus composes bulk of the structure
Fungal component usually is ascomycete
Photobiont is cyanobacteria or green algae
Relationship is a mutualism
Ecological Roles of Lichens. Lichens survive in hostile habitats and colonize new habitats.
Absorb mineral ions from substrates Cyanobacteria-containing lichens can fix nitrogen: Convert
atmospheric nitrogen to a form plants can use
Alternation of Generations
Sporophyte: Diploid (2N) spore producing body of the plant or algae. Undergoes meiosis to
produce haplod (1N) gametes.
Gametophyte: The haploid (1N), body in which gametes form during the life cycle via mitosis.
Gymnosperms
 Have Vascular tissue
 No water needed for fertilization
 Have cuticle and stomata
 Plants with “naked seeds”, seeds don’t form inside an ovary
 (No Flower, No Fruit!)
 Four groups (Conifers, Ginkgos, Cycads and Gnetophytes)
Conifer Characteristics
 Widest known, largest number of living species
 Woody trees or shrubs
 Most are evergreen
 Bear seeds on exposed cone scales
 Most produce woody cones
 Conifer Distribution
 Reproduce more slowly than angiosperms so they have a competitive disadvantage in many
habitats
 Still dominate in far north, at higher elevations, and in certain parts of southern hemisphere
Angiosperm Characteristics
•Vascular tissue
•No water needed for fertilization
•Have cuticle and stomata
•Have Flowers; Reproductive edge thanks to pollinators
•Ovules (seeds) are protected inside ovary (fruit)
All of these characteristics allowed for greater species diversity and angiosperms have been the
dominant plant on land for the last 100 million years; 90% of existing plants are flowering plants
About 3,000 species have 200 are now used as crop plants.
Answers to Questions posed in Lab 8 (Fungi & Seedless Plants)
Prelab:
Characteristics
Reproduce with spores
Gametophyte generation
Haploid stage prominent
Have true roots
Photosynthesize
Produce sperm & eggs
Produce pollen
Fungi
X
No
No
Seedless Plants
X
X
X
No
X
X
No
What is the difference between hyphae and mycelium found in the structural make-up of fungi
bodies? Answer: Hyphae are a single strand or chain of cells that make up the greater fungal
mass called a mycelium. Difference is a single unit vs. a complex.
Seedless Plants:
Describe the type of habitat where you would expect to find mosses, liverworts, horsetails and ferns.
Answer: Moist, usually stream side or where there is abundant moisture e.g. near springs.
Ferns and horsetails or more drought tolerant, and all can undergo a more dormant phase in
the year, but all need wet conditions to reproduce.
Explain the difference between the sporophyte and gametophyte generation found in all plants.
Answer: Sporophyte is diploid and makes spores, the gametophyte produces gametes and is
haploid.
In the space below sketch a fern frond and demonstrate where you would expect to find sporangia.
They are found on the underside portion of the leaflets of the greater leaf.
Trophic level
Fungi
Consumer
Plants
Producer
Animals
Consumer
Cell wall material
Chitin
Cellulose
(none)
Digestion
External
(irrelevant)
Internal
Food storage
carbohydrate
Glycogen
Starch
Glycogen
Where on the mushroom drawn below did this tissue originate? Answer: Underside of cap i.e. the
gills
Use the key to determine which group of fungi the Coprinus belongs to. How can you tell?
Answer: Based on the position of the spores and the presence of gills, this appears to be a
member of the Basidiomycetes.
Lichens
Many lichens are very flat and thin, how does this related to the way they get food?
Answer: They absorb nutrients from their substrate via hyphae, but they also have
photosynthesizing algae within them that are maximizing the capture of solar radiation.
List 3 lichens with Green algae symbiots:
Everninprunastri (others are available – large collection).
List 3 lichens with cyanobacteria symbionts:
Parmelia sulcata
Platismatia
(others are available)
Photosynthetic organism that gives Lobaria its bright green color: green algae
Look at the pale underside of the Lobaria.: Cyanobacteria
What special contribution can the second symbiont provide?
It provides supplemental nutrition depending upon resources available due to its ability to fix
nitrogen.
Evernia prunastri (oakmoss).
Sample measurements: Sample #2, Age 5 years, Length: 6 cm. Rate of growth 6/5 cm/yr, or about 1
cm per year.
Usnea: Answer is yes. Go here for information about its antibiotic properties and why it is dangerous
to take internally: http://www.itmonline.org/arts/usnea.htm
Speculate on why this genus of lichen might have allelopathic qualities: In order to outcompete
other lichens that are growing from trees in a very nutrient and water rich environment on
trees, in particular oaks.
Plants (pg 4):
1) Gametophyte
2) Sperm & Eggs (Gametes)
3) Fertilization, Structure is a zygote
4) Differentiation into Sporophyte (2N)
5) Meiosis
6) Germination and then Growth via mitosis
How has the ability to transport water changed moss growth forms, compared to liverworts?
Answer: Mosses are slightly taller than liverworts, meaning that they may be 2-5 cm tall,
whereas liverworts stay low to the ground.
Page 5
Reproduction in Moss
How does Psilotum get water and nutrients from the soil?
Answer: Mycorrhizae/hyphae of fungi
Refer to Chapter 23 in Starr & Taggert
1) Spores
Box – Germination and then Growth
2) Gametophyte
3) Sperm within antheridium
4) Egg within archegonium
Box – Fertilization
5) Zygote
Box – Growth via mitosis
6) Sporophyte (specifically a fern frond)
Box – Meiosis at site of sori
Box – release of spores
How has that affected the fern shape or size, compared to mosses? Answer: They have been
able to get bigger and grow more upright.
Familiar fern plants are sporophtyes. Therefore what reproductive cells do you expect them to
produce? Spores
Comparison chart of mosses and ferns:
Question
Color of gametophyte
(green or non-green)
Color of sporophyte
(green or non-green)
Which stage(s) perform(s) photosynthesis?
(sporophyte and/or gametophyte)
Which stage is larger?
(sporophyte or gametophyte)
Moss
Green
Fern
Green
Brown
Green
G
S&G
G
S
Answers to Questions posed in Lab 9 (Seed Plants)
Pre-lab Solution key (note that some answers may be used more than once):
1. Pine tree.
2. Male cones; female cones (order may be reversed).
3. Pollen grains.
4. Ovules.
5. This sentence has no blanks to be filled in.
6. Meiosis.
7. Eggs; sperm.
8. Pollen grain; fertilizes.
9. Zygote; embryo; seed.
10. Seed coat.
11. Pine tree.
Main lab:
Gymnosperms
Life Cycles: The Starr & Taggart text provides a view of the pine life cycle in Chapter 23. Answers
are:
Structure 1 is a sporophyte.
Female structure in 4 is an ovule.
The cell divisions that are occurring between stages 4 and 5 are meiosis.
The process occurring between 6 and 7 is fertilization.
The structures in 10 are the seeds.
The cell divisions occurring between 11 and 1 are mitosis (growth of the pine tree).
Examination of cones: there were woody female cones and flimsy male Douglas-fir cones, with the
male cones spilling pollen grains. Why the difference in cones?
Answer: the male cones need only last long enough to release the pollen. Female cones are
the where the seed develops and thus must provide a sturdy, long-lived structure.
Pollen grains produce sperm, ovules produce eggs. Gymnosperms are heterosporous.
Angiosperms
Flower structure and life cycles: The S&T text provides an angiosperm life cycle diagram in Chapter
23. However, a better figure of flower parts is in Chapter 30. There is also another angiosperm life
cycle diagram in Chapter 30.
Ripening ovules become seeds, and ripening ovaries become fruits that contain the seeds.
Floral inflorescences:
Which is more likely to attract pollinators, the display produced by a large flower or a small one?
Large flower – detectable over a larger area.
However, large flowers can be disadvantageous: energetically expensive to grow and maintain,
heavy to support, inefficient use of resources, etc.