2ND EXAM CH 5 Flashcards
Which grasses studied so far are C3 (cool season).
Avena Fatua L (Wild Oats)
Bromus Diandrus (Ripgut Brome)
Bromus Tectorum L (Cheatgrass)
Dactylis Glomerata L (Orchard Grass)
Festuca Idahoensis Elmer (Idaho Fescue)
Poa Pratensis L (Kentucky Bluegrass)
Poa Secunda Presl (Sandberg Bluegrass)
Hesperostipa Comata (Needleandthread)
Stipa Hymenoides (Indian Ricegrass)
Agropyron Cristatum (Crested Wheatgrass)
Elymus Smithii (Western Wheatgrass)
Elymus Spicatus (Bluebunch Wheatgrass)
Taeniatherum Caput-Medusae (Medusahead Rye)
Which grasses studied so far are C4 (Warm season) plants?
Andropogon Gerardii (Big Bluestem)
Schizachyrium Scoparium (Littlen Bluestem)
Bouteloua Curtipendula (Sideoats Grama)
Bouteloua Eriopoda (Black Grama)
Bouteloua Gracilis (Blue Grama)
Buchloe Dactyloides (Buffalograss)
Hilaria Belangeri (Curly Mesquite)
Tobosa Multica (Tobosa)
Sporobolus Cryptandrus (Sand Dropseed)
Explain at least three physiological consequences of differences (science and implications) between C3 and C4 plants. (READ Additional Readings found on Moodle: Warm vs Cool season Plants).
C3 and C4 plants differ in the leaf anatomy and Enzymes used photosynthesis.
C4 have something inside the stomata to keep CO2 away from them.
C4 plants have developed a specailized leaf anatomy and a aditional metabolic pathway to upateke more CO2 at lower temperatures.
C3 more palatable to herbivors.
Why are these plants called C3 and C4 plants? What are the differences in terms of photosynthetic pathways? What does this mean in terms of “Range Management” of these plants?
C3 plants are cold weather, they reduce (fix) CO2 directly by enzyme ribulouse biosphosphate. More palatable to herbivors.
C4 plants are warm weathered plants.
A wild horse comes along and bites off the entire panicles (inflorescences) of Sandberg bluegrass and Kentucky bluegrass in the early summer. Foliage near the base of these two plants remains intact. Consult “North American Wildland Plants.” Which of these two plants is more drought tolerant? Which is likely to continue growing by means of rhizomes? Which is a bunchgrass?
Sandberg Bluegrass is tolerant to drought, reproduces ussing seeds and tillers. Survive drought. Bunchgrass?
Kentucky Bluegrass is not drought tolenrant and reproduces from rhyzomes, tillers and seeds. Survive grazing.
What is the difference between structural and non-structural carbohydrates?
Structural carbohydrates form portions of the cell and the cell wall and are complex compounds such as celluloses, hemicelluloses, and lignin. They are not reutilized by the plant in other metabolic reactions.
Nonstructural carbohydrates, also called total available carbohydrates, are translocated within the plant and used for growth, respiration, and so on. These carbohydrates in clude sucrose, fructosans, starch, and dextrins.
Name factors that are associated with increased grazing resistance in each of the following groups: grasses, forbs and shrubs.
Grasses: Higher propoetion of culmless(stemless) shoots tan species with low resistence. Greater delay in elevation of the apical buds than species with low resistance. Sprout more freely from basal buds after defoliation than species with low resistance. Higher ratio of vegetative to reproductive stems than species with low resistance.
Forbs: Produce a large number of variables seeds. Delayed elevation of growing points. Poison and chemical compounds reduce palatability.
Shrubs: Spines and thorns discourage browsing. Volatile oils and tannis reduce palatability. Branches make removal of inner leaves difficult. Only current year’s growth of most shrub species is palatable and nutritious. Removal of apical meristem may stimulate axillary bud development.
Most grasses respond similarly to defoliation. Explain.
False
Defoliation: the dormant period is the least critical for leaf removal.
What are some of the factors that determine the rate of photosynthesis?
Extra leaf area may reduce photosinthesis dude to shading of new leaves.
Briefly discuss several ways that “secondary compounds” interact with herbivory? What
happens? What is the cost to the plant?
Plant secondary compounds are recognized deterrents and toxins to a variety of herbivores. Secondary compounds could potentially cause a decrease in an animal’s ability to maintain water balance.
Give examples of photosynthetic compounds.
C3: First product of photosynthesis is a three-carbon compound called glyceraldehyde 3-phosphate. Almost immediately, two of these join to form a glucose molecule.
C4: These plants have a special enzyme that can work better, even at very low CO2 levels, to grab CO2 and turn it first into oxaloacetate, which contains four carbons.
Name and describe the least critical, moderately critical, and most critical periods for foliage removal.
Least critical period for foliage removal is within the dominant period because the plant is photosynthetically inactive.
Moderately critical is during a time of intermediate relative to defoliation response.
Most critical period for foliage removal for many plant species is from floral initiation through seed development.
Which factor in controlling grazing animals is most important?
A wide range of studies has consistently shown that “ Grazing Intensity” is most important.
From the perspective of large herbivore nutrition, why are we as human managers interested in removal of old plant growth and stimulation of new plant growth?
.
Why is removal of old growth easier to accomplish on smaller pastures compared to larger pastures, with the same number of grazing animals?
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