127 terms

Botany

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Apical Meristems
Localized regions of cell division at tips of shoots and roots which help sustain growth in length
Multicellular, Dependent Embryos
Zygotes kept within female tissues of a plant. Have placental transfer cells that enhance the transfer of nutrients.
Alternation of Generations
The gametophyte and sporophyte generations are the two multicellular body forms that alternate in the life cycle of land plants.
Embryophytes
Land plants with multicellular, dependent embryos
Gametophytes
Haploid and produce gametes
Sporophytes
Diploid and produces spores
Spores
Reproductive cells that can develop into a new organism without fusing with another cell
Sporopollenin
A very durable organic material which makes the walls of plants spores strong and protects from harsh environments
Sporangia
Found on the sporophyte generation and produce spores
Spore mother cells
Undergo mitosis and generate the haploid spores within a sporangium
Gametangia
Where bryophytes, pteridophytes, and gymnosperms all produce their gametes
Archegonia
Female gametangia with each archegonium producing a single egg cell and retaining it within the base of the organ
Antheridia
Male gametangia which produce many sperm cells that are released to the environment upon maturity and are the home of fertilization.
Cuticle
A layer consisting of polymers called polyesters and waxes which coats the epidermis of leaves and other aerial parts of most land plants in order to conserve water.
Stomata
Pores that allow exchange of gases between the
outside air and leaf interior.
Xylem
Carries water and minerals up
from the roots
Phloem
Distributes nutrients (sugars, amino acids, and other organic products)
throughout the plant.
Protonema
A mass of green, branched, one-cell- thick filaments produced by germinating moss spores
Gametophore
The mature, gamete-producing structure generated by the meristems
Rhizoids
Long, tubular single cells or filaments of cells.
Parts of a moss sporophytes
A foot, an elongated stalk known as a seta, and a spore-producing organ known as the sporangium or capsule.
Calyptras
A protective cap of gametophyte tissue which covers an immature capsule, lost when the capsule is ready to release spores.
Peristome
The upper part of a capsule which is often specialized for gradual spore discharge
Homosporous plant
The sporophytes produce one type of spore
Heterosporous plant
The sporophytes produces megaspores and microspores
Megaspores
Female gametophytes with archegonia
Microspores
Male gametophytes with antherida
Seed
Consists of a sporophyte embryo packaged along with a food supply in a protective coat.
Pollen grains
Develop in the anthers of stamens, and contain immature male gametophytes
Ovules
Develop in the ovary, and contain the female gametophytes
Embryo sac
The female gametophytes
Double fertilization
One sperm fuses with the egg to form diploid zygote and the other sperm fuses with 2 nuclei in the large center cell
Cotyledons
An embryonic leaf in seed-bearing plants, one or more of which are the first leaves to appear from a germinating seed.
Endosperm
A tissue rich in starch and
other food reserves that is made when the triploid nucleus in the center divides repeatedly.
Fibrous root systems
System in monocots that consists of a mass of thin roots that spread out below the
soil surface to extend the plant's exposure to soil, water, and minerals.
Taproot systems
System in dicots consisting of one large, vertical root that produces many smaller lateral roots which firmly anchor the plant in the soil and store food.
Root hairs
These absorb water and minerals in both monocots and dicots near the root tips, which increases the surface area of the root enormously.
Adventitious roots
Roots that rise aboveground from stems and leaves which can help support tall stems
Nodes
Points where leaves are attached
Internodes
The stem segment between nodes
Axillary bud
A structure with the potential to form a vegetative branch formed by each leaf and the stem
Terminal bud
Where growth of a shoot is concentrated
Apical dominance
The inhibition of the growth of the axillary buds partly due to the presence of the terminal bud
Blade
The broad thin part of a leaf apart from the stalk.
Petiole
The stalk in a leaf which joins the leaf to a node of the stem
Dermal tissue/epidermis
A single layer of tightly packed cells that covers and protects all young parts of the plant
Vascular tissue
Continuous throughout the plant and involved in the transport of materials between roots and shoots.
Xylem
Moves water and dissolved minerals from the roots to the shoots
Phloem
Moves sugar from leaves and tubers to "sugar sinks" such as roots and fruits.
Tracheids
Long, thin cells with tapered ends that function in
support as well as water transport.
Pits
Thinner regions of the xylem where only primary walls are present
Vessel Elements
Generally wider, shorter, thinner walled, and less
tapered than tracheids
Xylem vessels
The end walls are perforated, allowing for the free movement of water through them
Sieve-tube members
Cells lacking organelles such as the nucleus, ribosomes, and a distinct vacuole that create tubes which transport sucrose and other compounds in phloem
Sieve plates
The end walls between sieve-tube members in angiosperm which have pores that presumably facilitate the flow of fluid from cell to cell along the sieve tube.
Companion cells
Located next to each sieve-tube
member and the two are connected by the plasmodesmata.
Ground tissue
Tissue that is neither dermal nor vascular and makes up most of the plant which is divided into the pith and the cortex
Pith
Ground tissue internal to the vascular tissue
Cortex
Ground tissue external to the vascular tissue
Parenchyma cells
Least specialized cells which have primary walls that are relatively thin and flexible, and most lack secondary walls. They perform most metabolic
functions in a plant, such as photosynthesis.
Collenchyma cells
Have unevenly thickened primary walls and are used to help support the young parts of the plant shoot.
Sclerenchyma cells
Much more rigid than collenchyma cells, cannot elongate, and are found in regions
of the plant that have stopped growing.
Fibers
Sclerenchyma cells that occur in groups
Sclerids
Shorter than fibers and irregular in shape. Sclereids are responsible for the hardness in nutshells and seed coats.
Root Caps
Physically protects the delicate meristems as the root pushes through the soil in primary growth which covers the root tip.
Zone of cell division
1st stage of primary growth which includes apical meristems and primary meristems
Quiescent center
A population of cells that divide much more slowly than the other meristematic cells and
are relatively resistant to damage from radiation and toxic chemicals.
Protoderm
Produces the dermal tissue of the plant
Procambium
Produces the vascular tissue of the plant
Ground meristem
Produces the ground tissue of the plant
Zone of elongation
2nd stage of primary growth, where cells elongate sometimes to more than ten times their original length.
Zone of maturation
Cells of the root begin specializing in structure and function in the zone of maturation.
Vascular bundles
Where vascular tissue runs the length of the stem in strands in stems
Stomata
Tiny pores which allow gas exchange between the surrounding air and the photosynthetic cells inside the leaf
Guard cells
Specialized epidermal cells that flank the stomata
Mesophyll
Ground tissue of a leaf sandwiched between the upper and lower epidermis, which consists of parenchyma cells specialized for photosynthesis
Secondary plant body
Consists of the tissues produced during this secondary growth in diameter.
Vascular cambium
Produces secondary xylem and secondary phloem
Cork cambium
Produces a tough, thick covering for stems and roots that replaces the epidermis
Ray initials
Cambium cells that produce radial files of parenchyma cells known as xylem rays and phloem rays.
Fusiform initials
The cambium cells within the vascular bundles, which produce new vascular tissue
Periderm
Made up of the layers of cork and the cork cambium
Lenticels
Regions where the periderm splits open, allowing gas exchange for cellular respiration
Bark
All tissues external to the vascular cambium-secondary phloem, cork cambium, and cork
Proton pump
Hydrolyzes ATP and uses the released energy to pump hydrogen ions out of the cell.
Cotransport
A transport protein couples the downhill passage of one solute to the uphill passage of another, which works for both anions and neutral solutes.
Water potential
Affected by
solute concentration and pressure.
Aquaporins
Specific channels for passive traffic of water in the form of transport proteins, whichaffect
the rate at which water diffuses down its water potential gradient.
Symplast
A continuous pathway for transport of certain molecules between cells formed by plasmodesmata
Apoplast
A continuum of cells walls formed as the walls of adjacent plant cells are also in contact,
Bulk flow
The movement of a fluid driven by pressure, which is how water and solutes move through xylem vessels and sieve tubes
Mycorrhizae
Symbiotic structures consisting of the plant's root sand the hyphae of the fungi.
Endodermis
Surrounds the stele and functions as a last checkpoint for the selective passage of minerals from the cortex into the vascular tissue.
Casparian strip
A belt made of suberin
Root pressure
When water flows in from the root cortex and generate a positive pressure.
Guttation
The exudation of water droplets on leaf margins.
Translocation
The transport of food in the plant
Sugar source
A plant organ in which sugar is being produced by either photosynthesis or the
breakdown of starch, with mature leaves being the major sugar sources.
Sugar sink
An organ that is a net consumer or storer of sugar, such as growing roots, shoot tips, stems, and fruit.
Transfer cells
When the companion cells have numerous ingrowths in their walls that increases the cells' surface area, enhancing the transfer of solutes between apoplast and symplast
Mineral nutrients
Essential chemical elements absorbed from the soil in the form of inorganic ions.
Essential nutrients
A particular chemical element needed for a plant to grow from a seed and complete the life cycle, producing another generation of seeds.
Macronutrients
Elements required by plants in relatively large amounts
Microelements
Elements required by plants in small amounts
Alternation of generations
When haploid and diploid generations take turns producing each other.
Sporophyte
A diploid plant which produces haplois spores by meoisis
Gametophytes
Produced by mitosis of spores, develop and produces gametes
Sepals
Enclose and protect the floral
bud before it opens
Petals
Brightly colored to advertise the flower to pollinators.
Stamen
Consists of a stalk called the filament and a terminal structure called the anther; within which the
pollen is produced (in pollen sacs).
Carpels
Has an ovary at its base and a slender neck called the style,
which is topped by a sticky structure called the stigma.
Pollen grains
The male gametophytes which form within the pollen sacs of anthers.
Embryo sacs
The female gametophtyes which form within the oules in ovaries
Megaspores
Formed by meiosis of the megasporocyte which continues to grow and its nucleus divides by mitosis three times, resulting in one large cell with eight haploid nuclei.
Self-incompatibility
The ability of a plant to reject its own pollen and the pollen of closely related individuals.
Double fertilization
One sperm fertilizes the egg to form a diploid zygote. The other sperm combines with two polar
nuclei to form a triploid nucleus that will give rise to the endosperm, a food-storing tissue of the seed.
Endosperm
A food-storing tissue of the seed.
Fruit
Protects the enclosed seeds and aids in their dispersal by wind or animals.
Pericap
The thickened wall of the fruit
Hormones
Chemical signals that coordinate all parts of the organism.
Tropism
Any growth response that results
in curvatures of whole plant organs toward or away from stimuli
(Positive) Phototropism
The growth of a shoot
toward light
Auxin
Any chemical substance that promotes the elongation and growth, which is found in the embryos of seeds, meristems of apical buds, and young leaves.
Cytokinins
Stimulate cell division and differentiation, which are produced in actively growing tissues and work with auxin to stimulate cell division and influence the pathway of differentiation.
Gibberellins
Promote seed and bud germination, stem elongation, and leaf growth, stimulate flowering and development of fruit; affect root growth and differentiation and are found in meristems of apical buds and roots, young leaves, and embryos.
Abscisic acid
Generally slows down growth, keeps seeds dormant, closes stomata during stress conditions
Ethylene
Promotes fruit ripening, results in aging