Plants for moodle
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Transcript of Plants for moodle
Plants!
STS Biology
Unit 6
Mrs. Stein
Plant Kingdom Characteristics
– Eukaryotic– Autotrophic (photosynthetic)– Multicellular
Many aquatic “plants” are algae – No seeds or true roots
Life on land required many adaptations
Evolution of Plants
Land Plants Need to be protected from drying out and
methods to transport materials Early land plants were non-vascular and
live in very moist environments– Mosses and liverworts
Vascular plants have transport tissue– Xylem – thick, dead tissue which moves water
UP from roots to leaves
– Phloem – living tissue, transports FOOD (sugar) in both directions
Ferns were the first vascular plants
Seed Plants
Cycads, ginkos, pines, spruce
Seed Ferns
Extinct
1st seed plants
Gymnosperms
“naked” seed
Conifer: gametes in cones, not
fruits
Monocot
Angiosperms
Flowering plants
Oaks, corn, tulips
Seed(s) contained in fruits
Dicot
Male cone
Female cone
Advantages of Seed Plants Can live on land Seed coat provides protection and
prevents drying out - the seed can survive longer in harsh conditions
Contains food supply for embryo Water is not needed for
reproduction – pollinators and seed dispersal
Roots, stems, and vascular tissue moves materials greater distances
Seed Structures A cotyledon is a food storage organ which
functions as the first seed leaf Monocots – one cotyledon Dicots – two cotyledons Endosperm is also food storage Embryo will grow into the new plant Hypocotyl is below the cotyledon and
becomes the lower stem Epicotyl is above the cotyledon and
becomes the upper stem and leaves Radicle becomes the roots
Corn and Bean
Seed Germination
Monocots & Dicots
Vascular bundles scattered
Vascular bundles in a ring
Stem
Arranged in 3’sArranged in 4’s or 5’s
Petals
ParallelBranchedLeaves
FibrousTaprootRoots
1 cotyledon2 cotyledonsSeeds
MonocotDicotPlant Part
Monocots & Dicots
Leaves Function in food production (photosynthesis) Epidermal cells – outer layer of cells, covered
with a waxy cuticle– Stomata surrounded by guard cells
Mesophyll – cell layers containing chloroplasts– Palisade Layer – tall, closely packed, sit of most
photosynthesis– Spongy Layer – loosely packed, air spaces allow
gases to enter and exit the leaf
Leaf Cross Section
UpperEpidermis
Cuticle
Vein (vascular tissue)
LowerEpidermis
Spongy Mesophyll
Palisade Mesophyll
Stoma
Guard Cells
Stomata Greek for “mouth” Opening of stomata are regulated by guard
cells Water exits through stomata (transpiration) Site of gas exchange – CO2 in, O2 out
Roots Functions
– Absorb water and nutrients from soil
– Food storage (ie: carrots)– Anchoring the plant
Structure– Xylem and phloem– Epidermis – thin layer that
absorbs water and nutrients– Cortex – food storage– Meristematic Tissue – only site
of mitosis, found at tips of roots and shoots
Vascular Bundles in Roots Dicot roots have xylem in an “X” in the
center of the root Monocot roots have vascular bundles in
a circular pattern
Dicot Root Monocot Root
XYLEM
PHLOEMDicot RootVascular Cylinder
Stems Function
– Support plant, hold leaves up to the sun– Transport foot and water
Arrangement of vascular bundles– Dicots – arranged in a ring– Monocots – scattered throughout
Stems
Dicot Stem Monocot Stem
Flowers Reproductive structures of angiosperms Sepals are the outermost layer which
encloses a bud and protects the developing flower
Petals are just inside sepals, fragrance and color attracts pollinators
The receptacle is where sepals, petals, and sex organs attach
Flowers (cont.) Stamen - male sex organ
– Anthers produce pollen– Filaments hold the anther up for
pollinators or wind Pistil (aka carpel) – female sex organ
– The stigma is the sticky end where pollen lands
– The style is the “neck” which connects the stigma to the ovary
– The ovary contains ovules, when mature the ovary becomes a fruit
Flower Anatomy
FilamentSta
men
Anther
PistilStyle
Stigma
Petal
Ovary
Ovule
Receptacle
Sepal
Pollination Pollen transfers from anther to stigma
– Self-pollination – pollen fertilizes the ovule of the same plant
– Cross-pollination – pollen fertilizes ovules of another plant, thus increasing genetic variation
Cross Pollination Methods Wind Pollination
– Inefficient, high pollen production – Flowers (if present) are small and not
colorful
Cross Pollination Methods
Vector pollination uses animals to carry pollen between plants
More efficient, less pollen produced Plants attract pollinators by:
– Colorful petals– Fragrance– Nectar production
Coevolution Two species evolve in response to
changes in one another
Bee Pollination
Butterfly Pollination
Bat Pollination
Moth Pollination
Seed Dispersal Wind scatters seeds
– Maple trees, dandelions
Animal dispersal occurs when barbs stick to animal fur– Burdock plant
Animals eat and digest fruits, seeds are excreted
Fertilization
1. Pollen lands on stigma
2. Pollen tube grows into the style
3. Sperm and egg unite forming and zygote
Double Fertilization Two sperm enter the ovary The 1st sperm fertilizes the
egg resulting in a zygote (2N) The 2nd sperm fertilizes the
polar nuclei forming the endosperm (3N)
http://bcs.whfreeman.com/thelifewire/content/chp39/3902001.html