Biology - Plants
13.1 - Plants as Valuable Bioresources
- The Biosphere Depends on Plants * photosynthesis: a series of chemical reactions that converts energy from sunlight into chemical energy stored in molecules * cellulose: a large carbohydrate molecule
- Plants as a Source of Food * agriculture: farming or forestry practices that produce food and goods
- Food Security * food security: the state where all people, at all times, have access to enough safe and nutritious food to meet their dietary needs and preferences and allow them to lead an active and healthy life * sustainable agriculture: an approach to agricultural production that integrates economics, the environment, and society in meeting the nutritional needs of the world
- Plants as a Source of Fibres and Building Materials * textile: a fabric, flexible material, or related product made from natural or synthetic fibres, threads or yarns * timber: trees in their natural state or wood that has been prepared for use as a building material
- Plants as a Source of Biochemicals * medicinal uses
- Plants as a Source of Fuel biofuels a fuel that is produced from renewable biological sources
- Plants and Erosion Control
- Plants, Recreational and Ecotourism

13.2 - The Vascular Plant Body
- Plant Classification : Vascular vs. Non Vascular
- Vascular Plant Systems : Shoot System (above ground): the stems and leaves of a plant; stems: bear structural support and, in some cases perform photosynthesis leaves: specialized for photosynthesis Root System (below ground): the roots of a plant roots: anchors the plant and absorbs the water and mineral nutrients the plant needs
- Anatomy of Plant Cell: *chloroplast*vacuole*cell wall
- Plant Cells 1. Parenchyma (mature=alive): - spherical shape - cell walls flatten when packed together - felxible thin walled - wide range function - storage, photosynthesis, gas exchange, protection, tissue repair/replacement - leaves/stems: contain many chloroplasts to make glucose - roots/fruits: large central vacuoles for storage 2. Collenchymas (mature=alive) - elongated long strands - provide support - uneven thickness of cell wall - gives flexibility - bend without breaking - tissue repair & replacement 3. Sclerenchyma - thick secondary cell walls containing lignin (strong substance makes cell tough & hard) - primary function = support for mature plants - @ maturity: - most die after development - lack cytoplasm & other living components - thick rigid cell walls remain - gritty texture of pears, hard covering of seedcoat - 2 types 1) sclereids: gritty pears 2) fibres: thick cell walls when stacked end to end
4 Main Types of Tissues 1. meristematic tissue - new tissue is produced through mitosis - present in all vascular plants - present in difference regions of a plant - embryonic tissue - make up "meristems"- areas of rapidly dividing cells - as they mature, meristematic cells specialize into other cell types - primary growth (tall) - apical meristem - tips of stems & roots - intercalary meristem - stems and @ base of leaf blades - secondary growth (fat) - lateral maeristem - increase in root & stem circumference; adds vascular tissue, strengthens stems, support for plant as it grows - vascular combium- thin layer length of root & stem: new vascular tissue - cork cambium - cells for cell walls; protective layer on outside of stems & roots; makes up outer bark 2. dermal tissue - epidermis - single layer to protect non-woody plants - periderm - replaces epidermis to form cork in woody stems & plants - specialized epidermal tissue - guard cells (controls stomata size) - stomata = pores - used in cellular respiration (co2 in, o2 out) - trichomes - tiny growth on leaves and stems - fuzzy leaves - function: cool & reduce evaporation - root hairs - covers roots increase surface area 3. ground tissue - forms most of the inside tissue of a plant - wide range of functions *photosynthesis * storage: starch & oils *support

4. vascular tissue - internal system of tubes running lengthwise throughout the stem of aplant - connects roots and leaves to stem - transport water and nutrients - two types: XYLEM PHLOEM - organized in "vascular bundles"

XYLEM - transports water & minerals - roots leaves - in gymnosperms: consists of "tracheids" - in angiosperms: consists of "tracheids" & vessel elemnts - cells are dead @ maturity - fluids tranport from on tracheid or vessel element to the next via pores called "pits"
PHLOEM
- transports nutrients such as sugars - to areas needing energy for growth & metabolism - to roots for storage - "food conducting" tissue - two types: - sieve tube elements & companion cells - both types are alive @ maturity - tube cells have "sieve" like holes between them to allow for transport of nutrients

13.3 (see other paper)

Transport In Plants * Transport in the Xylem
- carries water from root to leaves UPWARDS * diffusion: net movement of particles from an area of high concentration to an area of low concentration until the concentrations between the two areas are balanced * transpiration: the process in which water evaporates from the inside of a leaf to the outside through the stomata * root pressure: the mechanism by which positive pressure in the roots moves water upward in a plant * cohesion: force of attraction between water molecules in each narrow xylem tube proves a force that keeps the water column unbroken while it is being pulled up under tension * adhesion: causes the water molecules to stick to the xylem walls and helps keep the water column from breaking as it is pulled upward * Transport in the Phloem
- carries nutrients in all direction
- linked by sieve plates * translocation: the transport of sucrose and other organic molecules through the phloem of a plant * pressure-flow model explains how translocation moves organic molecules from a source, where they are entering the phloem, to a sink, where they are being used to or stored. * turgor pressure the movement of sugar in plants
Plant Growth and Development
- hormone: a chemical compound produced in one part of the plant that controls growth activity in another part of that plant Hormone | Selected Key Functions | Where Produced or Found in Plants | Stimulatory Hormones | Auxins | - stimulate cell division and elongation in stems and roots- regulate cell expansion in plant responses to light and gravity | - developing leaves and seeds- shoot tips | Cytokinins | - stimulate cell division- prevent ageing of leaves | - root tips | Gibberellins | - stimulate cell elongation- stimulate seed germination | - young shoots- developing seeds | Inhibitory Hormones | Ethylene | - promotes ripening of fruit | - all parts, especially when under stress, ageing or ripening | Abscisic Acid | - induces and maintains seed dormancy- inhibits shoot growth- closes stomata | - mature leaves- plants under stress | additional information: auxins: - apical dominance: a condition of a plant stem in which growth is mainly upward, with little growth laterally from side branches

Plant Responses to Environmental Stimuli
- nastic response: a plant's movement in response to a stimulus that is not associated with the direction of the stimulus.
TROPIC RESPONSES
- tropism a plant's growth response to external stimulation coming from one direction in the environment
- phototropism a plant's growth response to light
- gravitropism a plant's growth response to gravity
- thigmotropism a plant's growth response to touch or contact

Other Factros that Affect Plant Growth
- Nutrients
- Soil pH

Succession & Sustainability
Plants as Ecosystem Pioneers * ecological succession the change in an ecosystem that happens when one community replaces another; it results from changes in abiotic and biotic factors

- Primary Succession the establishment of a community to an area of exposed rock that does not have any topsoil - Pioneer Species the first organisms to appear in primary succession - Climax Community the final stage of ecological succession
- Secondary Succession the changes that take place in an ecosystem that has been damaged, or in communities that have been destroyed but the soil has remained intact
- Frequency of Ecological Disturbances *more frequent than before