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24 Cards in this Set
- Front
- Back
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Plant ground tissue
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Parenchyma- most common, have thin walls and function in storage, photosynthesis, and secretion
Collenchyma- have thick but flexible cell walls and serve mechanical support functions Sclerenchyma- thickest walls and provide mechanical support functions |
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Dermal tissue
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Consists of epidermis cells that cover the outside of plant parts, guard cells that surround stomata, and various specialized surface cells such as hair cells, stinging cells, and glandular cells. Also responsible for forming the cuticle.
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Vascular tissue
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Xylem- Conduction of water and minerals and provides mechanical support. Xylem cells have a secondary cell wall that gives additional strength. Most xylem cells are dead at maturity. Two types: tracheids and vessel elements
Phloem- Functions in the conduction of sugars. Made of sieve-tube members and are alive at maturity. |
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The seed
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Consists of an embryo, seed coat, and some kind of storage material (endosperms or cotyledons)
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Embryo
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Consists of epicotyl (becomes the shoot tip), plumule (young leaves), hypocotyl (young shoot), radicle (root), sometimes a coleoptile (protects the epicotyl)
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Germination
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After a seed reaches maturity, it remains dormant until specific environmental cues (water, also temperature, light, or seed coat damage) are encountered. Germination begins with the imbibition of water which initiates activity of various enzymes so that biochemical reactions can start. The water also causes the seed to swell and the seed coat to crack.
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Apical meristem
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Where primary growth occurs in young seedlings. This area contains meristematic cells.
Behind is the zone of cell division and then there is the zone of elongation and the zone of maturation. |
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Primary growth vs. secondary growth
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Primary growth is experienced in many plants and is when actively dividing cells occur only at the apical meristem and increase the shoot length. Forms primary tissues.
Other plants (conifers and woody dicots) also undergo secondary growth. This increases girth and is the origin of woody plant tissues. Occurs at the vascular cambium and the cork cambium (gives rise to periderm, the protective material that lines the outside of woody plants). |
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Structure of roots
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Epidermis- lines the outside of roots, root hairs are produced to increase absorption
Cortex- makes up the bulk of the root, storage of starch Endodermis- ring of tightly packed cells at the innermost portion of the cortex and where the Casparian strip is found Stele- makes up the tissue inside the endodermis |
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Structure of stems
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Epidermis- contains the epidermal cells covered in waxy cutin (forms the cuticle)
Cortex- various ground tissues that lie between the epidermis and the vascular cylinder (contains chloroplasts) Vascular cylinder- consists of xylem, phloem, and pith. Arrangement can vary. |
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Vascular cambium
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Originates between the xylem and phloem and is the site of secondary growth. Inside cells become secondary xylem whereas cells on the outside become secondary phloem. Secondary xylem accumulates and increases the girth of the stem and root. Also, new secondary phloem is added yearly.
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Cork cambium
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Produces new cells to replace the shed epidermis. On the outside, a layer of protective cork cells is produced. On the inside, phelloderm may be produced.
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Leaf structure
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Epidermis- protective covering of one or more cells, covered by cuticle.
Palisade mesophyll- parenchyma cells equipped with numerous chloroplasts for photosynthesis. Spongy mesophyll- consists of loosely arranged mesophyll and intercellular spaces that hold CO2 Guard cells- specialized epidermal cells that control the opening and closing of the stomata (allow gas exchange to occur) Vascular bundles- consist of xylem and phloem tissue |
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Apoplast vs. symplast
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Both describe water movement in plants; apoplast is water that moves through cell walls and intercellular without ever entering the cells (consists of nonliving portions of cells). Symplast is when water moves from one cell to another through the symplast, or living portion of the cell. Moves through plasmodesmata (small tubes)
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Water movement in plants
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1. Osmosis by root pressure (guttation)
2. Capillary action 3. Cohesion-tension theory- transpiration, cohesion, and bulk flow |
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Auxin
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Promotes plant growth by facilitating the elongation of developing cells. This is done by increasing the H+ concentration in primary cell walls. Then enzymes are activated to loosen cellulose fibers (increase in wall plasticity).
Produced at the tips of shoots and roots where it also influences responses to light and gravity. |
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Gibberellins
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Hormones that promote cell growth. Synthesized in young leaves, roots and seeds and are transported to other parts of the plant. Involved in the promotion of fruit development and of seed germination and in the inhibition of aging leaves. High concentrations cause rapid elongation of stems (called bolting)
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Cytokinins
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Group of hormones that stimulate cytokinesis and are produced in the root and then transported elsewhere. They have many effects that change with the presence of auxin. Involved in organogenesis and weaken apical dominance.
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Ethylene
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Gas that promotes the ripening of fruit by enzymatic breakdown of cell walls. Also involved in flower production. Inhibits the elongation of roots, stems, and leaves and influences the aging of leaves.
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ABA
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A growth inhibitor that causes the formation of scales in preparation for overwintering. Also involved in maintaining dormancy.
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Phototropism
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Response to light, achieved by the actions of auxin.
Auxin is produced by the apical meristem, moves downward by active transport into the ZOE and generations growth. Equal illumination results in equal growth and unequal illumination results in increased concentrations of auxin in shady sections of the stem (which then grows more than the sunny side) |
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Gravitropism
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Response to gravity. Both auxin and gibberellins are involved and action depends on their concentrations and the target organ.
If a stem is horizontal, auxin accumulates on its lower side and stimulates cell elongation, causing the stem to bend upward. |
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Thigmotropism
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Response to touch
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Photoperiodism
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Response of plants to changes in the photoperiod, or length of daylight and night. Plants maintain a circadian rhythm, a clock that measures the length of daylight and night.
Phytochrome is involved. |
