Life 103- week 5
Life 103- week 5 LIFE 103
Popular in Biology of Organisms-Animals and Plants
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This 5 page Class Notes was uploaded by Alexis Darling on Friday February 19, 2016. The Class Notes belongs to LIFE 103 at Colorado State University taught by Jennifer L Neuwald; Tanya Anne Dewey in Fall 2016. Since its upload, it has received 19 views. For similar materials see Biology of Organisms-Animals and Plants in Biology at Colorado State University.
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Date Created: 02/19/16
Finishing up Angiosperms… Vocab: cotyledon initial ‘leaves’ for energy purposes; thicker than normal leaves, not specialized for photosynthesis ~Monocots ○ more than 70,000 species ● One cotyledon ● parallel veins on leaves, flowers, etc ● vascular tissue placed randomly through the stem ● fibrous roots (no main root) ● pollen grain has only 1 opening ● petals and other floral organs in multiples of 3 (3,6,9, etc) ❖ Includes: orchids, palms, grasses (grasses too have flowers, just tiny and slightly hidden) ~Eudicots (“Eu”=true, “di”=two, “cots”=cotyledons) includes most dicots ○ more than 170,000 species ● Two cotyledons ● branching veins through leaves, flowers, etc ● organized vascular tissue; makes a ring if you look at a cross section of a stem ● taproot/ main root ● pollen grain has 3 openings ● petals and other floral organs in multiples of 4 or 5 ❖ Includes: legumes, roses, most flowering trees ~Basal Angiosperms ○ 100 species ❖ Amborella ❖ Water Lillies ❖ Star Anise ~Magnoliids ○ 8,000 species ❖ Magnolias ❖ Laurels *Seed plants are crucial for humans by providing a great part of our food, fuel, wood, and medicine. Always remember the 5 key traits derived by seed plants: ★ smaller gametophytes as reduced part of life cycle ★ heterosporous have two types of spores, which develop into either male OR female; ★ ovules (the female gametophyte) ★ pollen (the male gametophyte) ★ seeds formed after fertilization Plant Structure Summary Two main systems: Shoot system, made up of leaves and stem, and Root system, made up of roots. All leaves, stems, and roots are made up of dermal, vascular, and ground tissue. All tissues are made up of parenchyma, collenchyma, and sclerenchyma cells. ~Roots : Purposes hold plant firmly in ground absorb water and minerals from underground storage for carbohydrates/sugars Parts taproot (mainly eudicots have this system) main root which extends deeply vertically; can tap into deep water sources lateral roots extend off of tap root like branches improve security in the ground, site of most water absorption root hairs grow off of lateral roots, fine/thin for maximum surface area Types of root systems Taproot allows plant to grow tall easier to pull up but stronger to support altitude of the plant Fibrous adventitious roots form network directly off of stem once the radicle dies *holds plant in to survive grazing animals, but plant does not grow tall Evolutionary adaptations prop roots splay out to support top heavy plants storage roots hold a ton of carbohydrates pneumatophores aerial roots that can absorb oxygen when above water at low tide ~Stems : Purpose elongate shoot and grow it taller to achieve best photosynthesis Parts nodes spots where leaves grow off of main stem internodes stem segments between nodes apical buds shoot tips at growing ends axillary buds like axillary buds but located between the stem and where the leaf grows out(node); grow if apical bud is taken off, results in bushy growth, not long like from apical buds Rhizome modified stem that grows horizontally underground and starts new shoots (asexual reproduction) Stolon modified stem which grows horizontally above ground and each node forms a new plant (asexual reproduction) tubers stems underground which store carbohydrates and also grow new plants out of ~Leaves: Purpose intercept light exchange gases release heat defend against herbivores and pathogens Parts flattened blade petiole stalk which connects leaf to main stem Types simple leaf single blade attaches at one node with one axillary bud complex leaf multiple blades (all connected by petiole) attach at one node with one axillary bud spines ex; on a cactus reproductive leaves storage leaves ex; onion layers tendrils looks like a vine; grows to extend and hold onto other structures All parts of plants (roots, stems, leaves) are made up of 3 types of tissues: ~Dermal Tissue outer covering, like skin, defense mechanism Parts epidermis outermost layer of cells cuticle waxy coat over epidermis cells to prevent dessication *roots hair is an extended epidermal cell ~Vascular Tissue transport food and water and provide structural support Parts Xylem for water and minerals; moves from roots to shoots (only up) ● Tracheids (die at maturity) ● Vessel elements (die at maturity) Phloem for sugars; moves from shoots (photosynthetic leaves) to roots (storage) or from storage to where needed (goes both directions) ● Sieve plates the cell walls between the cells that make up phloem have pores to allow flowing of fluid; all together make up; ● Sieve tube organellelacking cells yet stay alive with companion cells that provide necessary proteins ~Ground Tissue storage and support pretty much everything that’s not dermal or vascular Parts pith inside vascular tissue cortex outside of vascular tissue All tissues made of different proportions of 3 types of cells: ~Parenchyma cells ● Thin walls, therefore flexible to allow further growth ● Least specialized yet complete most metabolic functions ● Can still differentiate and grow ○ ex: cells containing chloroplasts, cells storing starch ~Collenchyma cells ● Thicker walls than parenchyma to support, yet still flexible to not inhibit growth ● Grouped in strands ~Sclerenchyma cells ● Very thick secondary walls to provide rigid support (LIGNIN) ● Only found in mature parts; no more growth ● Once they have formed to proper function they die at maturity *Often alongside xylem Plant Growth Plants typically haveindeterminate growth, meaning they continuously grow until death. Certain plant parts follow determinate growth, meaning they grow until they reach a certain size and then stop (leaves, flowers). Meristems allow for indeterminate growth as they are always embryonic tissue. 2 types of meristems: ● Apical meristems for primary growth (elongation), located on root and shoot tips ● Lateral meristems for secondary growth (growth in diameter), 2 types; ○ Vascular cambium ○ Cork cambium Primary growth of Roots: (From root tip going back) ❖ Root cap covers apical meristem to protect the dividing and growing cells as they push through the rough soil ❖ Zone of cell division meristem area; site of mitosis to create more cells ❖ Zone of elongation area where cells lengthen by filling central vacuole with water (allowing fast growth); this is what is responsible for the increase in root size, pushing it further through the soil ➢ Cellulose microfibrils wrap the cells like a slinky to direct elongation ❖ Zone of differentiation here cells have differentiated to each have a specific function Other parts and traits ● Endodermis inside layer of the cortex; permits only certain substances to pass into the vascular cylinder (keeps toxins in soil out) ● Pericycle outer layer of vascular cylinder; from where lateral roots begin ● Eudicots have their xylem and phloem arranged like a + or star in their roots. ● Monocots have them arranged in a ring in their roots. (different in stems…) Primary growth of Shoots: ❖ Apical meristem ❖ Leaf primordia embryonic tissues which develop into leaves; located around the sides of the apical meristem ❖ Axillary buds develop out of meristematic cells; at the bases of leaf primordia ● Apical dominance the closer an axillary bud is to the apical meristem, the less it can grow because hormones inhibit it; if the apical bud is removed or shaded then the axillary bud can branch out Tissue Organization of Stems: Vascular tissue is arranged into bundles. Most eudicots have their vascular bundles arranged into a ring pattern. Most monocots have their vascular bundles scattered throughout their ground tissue.
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