36 Plants Flashcards
Plants general
Autotrophic organisms which are able to synthesize all required organic compounds from inorganic substances using sunlight. Multicelled and eukaryotic. Beta glucose linkage
Vascular plants
Specialized tissue : xylem and phloem
Xylem
Conducts water and minerals from roots to the rest of the plant in one direction. Support. Xylem transports UP. Xylem makes up wood, xylem rings.
Phloem
Carries sugar from leaves to the rest of the plant. Main conducting cells are called sieve tub members. Sugars that are made by photosynthetic leaves are loaded into the tube members with the help of companion cells.
Phloem can transport up or down.
Cuticle
Waxy coating, hydrophobic. impermeable to CO2, stomata allow CO2 to diffuse through.
Transpiration
H2O evaporation in plants
In most plants, stomata stay ____ during the daylight
Open, when photosynthesis occurs. CO2 can enter, H2O is lost.
At night, stomata closed, CO2 accumulates and water is conserved.
Guard cells
When water builds up, they become swollen and open up to allow water vapor loss and CO2 entry in the leaf.
Soil suited for plant growth characteristics
Aeration and H2O holding capacity
Roots
All begin with a primary root then differentiates into smaller secondary roots. Root surface area is increased by root hairs. Root tip = meristem
Root structures
Epidermis: outermost layer includes root hairs
Cortex: stores starch: contains parenchymal cells
Endodermis: innermost layer of cortex, with a waxy tissue band called casparian strip. Involved in controlling the uptake of water and dissolved nutrients.
Stele/Vascular cylinder: Layer of cells inside the epidermis contain xylem and phloem. Cambium tissue lies between xylem and phloem, to thicken the root. Pericycle is the outer layer of the stele which can initiate development of secondary roots
On roots of legumes we see swelling called root __
nodules. Contain nitrogen fixing bacteria which convert atmospheric N2 to NO3- and NH4+.
Nitrification
Break down of dead organisms to release NH4+ to be oxidized into NO3-
Denitrification
Form N2 and a small amount of N2O as NO3- and NO2- are converted into these products. Nitrogen Cycle
3 types of ground tissue which differ in cell wall structure
Parenchyma, Collenchyma, Scelrenchyma
Parenchyma cells
Most abundant, thin walls in roots, stem, leaves
Storage, secretion, and photosynthesis
Collenchyma
Cell walls are thick, but flexible support for growing stem
Scelerenchyma Cells
Very thick cell walls, contain lignin (2nd most abundant natural polymer in the world) Lignin and cellulose work as a team to provide strength.
Stems
Root system usually beneath the ground, while a shoot system is above the ground.
Stem function
a) Support shoot system structure
b) Transport substances between roots and the leaves
c) Store food
Angiosperms (seed plants)
Flowering plants, pears, strawberry, cherries, raspberries, apples. 90% of plants are angiosperms, most diverse and produces seeds.
As seeds develop from ___ after fertilization
Ovules, the ovary becomes the fruit.
Cotyledon
A seed leave of a plant embryo
Monocots
1 Cotyledon, leaf veins are parallel, scattered vascular bundles, cambium absent, flowers in multiples of three
Dicots
2 cotyledons, leaf veins are netlike, ringlike vascular bundles, cambium present, flowers in multiples of 4,5
Male flowering part
Stamen:
a) Anther: chamber where pollen grains develop
b) Filament: stalk
Female flowering part
Carpel:
a) Ovary: eggs develop, fertilization occurs, and seeds mature
b) Style: a connecting stalk
c) Stigma: sticky part to catch pollen
Sepal
Protection to the flower, collectively the sepals are called the calyx.
Ovule
Stalked structure that develops on the ovary wall. It consists of egg and surrounding tissue. The ovule becomes the seed.
Plant fertilization
Stigma catches the pollen, it travels down the pollen tube and finds a receptive ovule inside the ovary. Embryonic seed is formed.
What is unique to angiosperms?
Fruits, flowers, and double fertilization.
What is double fertilization?
The egg fuses with one sperm and a zygote (2N) is made. The other sperm fuses with two polar nuclei cells to make a 3N cell which gives rise to the nutritive tissue. AFter the ovule becomes the seed and the ovary becomes the fruit.
Gymnosperm
Plants with naked seeds, came before angiosperm. Nonflowering plants, seeds are not enclosed in a chamber but exposed on modified leaves that form cones.
Conifers, Fir, Pine, Cedar, and Spruc, Cyads
Megaspore and microspore
Megaspores develop in the ovule into female gametophytes.
Microspores develop in the anther into the pollen grains which develop into male gametophytes which give rise to sperm cells.
Self pollination
Pollen grains are transferred from the anther to the stigma of the same flower or at the ovule in the case of a non flowering plant like a gymnosperm.
Cross pollination
Transfer pollen from the anther of a flower of one plant to the stigma of a flower on another plant.
Some plants can not self fertizilies
Mechanism to limit or prevent self fertilization
Dioecious species
Plants with distinctly male or female structures.
Plants are asexually reproduce
Resulting plants are clones.
Plants and meiosis
Meiosis produces spores which are haploid. Spores do not undergo fertilization. Spores divide by mitosis to produce a multicellular haploid plant. Development of haploid spores into haploid bodies needs two forms: Haploid and diploid body, that alternates. Alternation of generations
All plants display alternation of generations
Haploid and diploid body forms.
Bryophytes
Non vascular, oldest land plant, no xylem or phloem tissue. Need water for fertilization.
Moss, liverworts, and hornworts
Waxy cuticles to control H2O loss
Rhizoids = root like absorptive structures. Life cycles are dominanted by gametophytes.
Bryophytes male and female gamete gametangia
Achegonia : female gametangia
Antheridia: Male gametangia
Ferns
Seedless vascular plants, largest group
Leaves are called fronds.
Sori found on the lower surface of many fern fronds. These are sporangia (containing spores) clusters that are yellow. Have a vascular tissue which allow them to grow taller than bryophtes.
Sporophyte dominates the fern life cycle. Meiosis in the sporangia, making haploid spores.
Ferns are unique, they use spores and not seeds. Ferns have no flowers.
Plant hormones
Auxin, Cytokines, Gibberellins, Abscisic acid, Ethylene
Auxins
Promote stem elongation, fruit development
Apical meristems and leaves show most abundance
Cytokines in plants
Stim cell division, delays leaf aging, abundant in roots
Gibberellins
Like auxins, promotes stem elongation, pollen development, fruit development
Works with auxins and involved in flowering process
Abscisic Acid
Inhibit plant growth, seeds from germinating
Causes stomates to close during draught
Ethylene
Gas that stims green fruit to ripening. Allows bananas, melons to ripen quicker.
What is a tropism? In plants
Growth response to environmental factor
Gravitropism, phototropism, thigmotropism
Gravitropism
Direction growth in response to gravity
Phototropism
Growth in response to light
Thigmotropism
Growth in response to physical contact
Photoperiodism
Biological response to a change in daylight length and darkness in a 24hour day.
Phytochrome
Blue green pigment that absorbs red light.
