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によって Alexander Boldis 4年前.

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Unit 5: Plant Organisms

The text provides an in-depth examination of plant organisms, focusing on various structural and functional aspects. It details the anatomy of flowers, highlighting the roles of petals, stamen, pistil, and sepals in reproduction and protection.

Unit 5: Plant Organisms

Unit 5: Plant Organisms

Plant Transportation

Transportation of Water/Nutrients
3. Transport into Leaves

Leaves are main driving force of xylem upward

Transpiration

Factors Affect Transpiration

Number of Stomata per Leaf Surface Area: More stomata = Higher transpiration rate

Wind – High transpiration rate in high winds

Humidity: High transpiration rate in low humidity

Light: High transpiration rate during day since stomoa is open

Temperature: High transpiration rate in high temperature

Evaporation of water through the stomata of plant leaves

2. Transport into Stem

Xylem sap rises due to root pressure and capillary action

Capillary Action: Water rise because of attractive forces between water molecules and side of wall

Root pressure: Osmotic force pushes xylem sap upward

Water molecules and dissolved nutrients called xylem sap

1. Roots absorb nutrient/water

Nutrients (Active Transport)

From low concentration (outside cell) to higher concentration (inside cell)

Water (Osmosis)

Water moves to vascular cylinder

Cytoplasm has less water than soil

Root Hairs

Form symbiotic association with fungi (mycorrhizae)

Increase SA to absorb more nutrients/water

Transportation of Sugars
3. From phloem cells to sink cells

Water re-circulated into xylem

Passive transport: High concentration of sugar in phloem, low in sink

2. Through Pholem

Not Well Understood

Translocation moves sugars from phloem cell to phloem cell

1. Source to Pholem

Water moves from xylem to phloem when high concentration of sugar through osmosis

Active transport of sugars across cell membrane

About transportation

Sugars can move up/down (Nutrients moves only up)

Sink: Cells with low concentration of sugars

Source: Cells with high concentration of sugars

Vascular Cylinder
Phloem

Sieve tubes

Companion cells that direct activities and supply nutrients

Between are sieve plates (large pores to facilitate transport)

Long, hollow tubes

Transports sugar through the plant

Living Tissue

Xylem

Types of Xylem

Vessel Elements:long, wide; joined together; more efficient

Trachiod: Long,Narrow; Trapid at ends

What is it?

Long, hollow tubes formed by non-living cells

Transports water/minerals from roots to stem/leaves

Reproduction

Sexual Reproduction
Pollen (male gamete) enters ovary (female gamete) and fertilizes into a seed
Asexual Reproduction
Cutting: part of plant falls off
Grafting: Combine several varieties of fruit
Runners: Drops new shoots into the ground and establishing new roots

Plant Body

Types of Plants
Dicotyledons (Dicots) (Oak trees, dandelions, canola)
Monocotyledons (Monocots) (Orchids, grass, lilies)
Flowers
Structure of Flower

Pistil: Female Reproductive Organ

Ovary:Contains ovule (female gamete)

Stigma: Sticky tip to collect pollen grain

Stamen: Male Reproductive Organ

Anther: Produces pollen grain (Male Gametes)

Filament:Connects Anther to flower

Petals: Colourful to attract pollinators

Sepals:Covers and protect flower buds before blossom opens

Dicot: Multiples of 4 or 5 petals
Monocot: Multiples of 3 petals
Leaves
Types of leaves

Leaf Vein Structure

Monocots: Parallel, Leaf sheet

Dicots: Branching, Petiole

Leaf Shape

Gas exchange

Photosynthesis

Defense

Internal Structure

Guard cells: control opening and closing of stoma

Stoma:gas passes in or out

Mesophyll cells (middle): contain chloroplast

Spongy: loosely packed, loosely packed for gas exchange, bottom layer

Paliasids:closely packed, upper layer

Epidermal cells (outside): covered in waxy cuticle

Seeds
Germination (Development of seed)

Dormancy – resting period

Absorption of water by the seed

Embryo releases growth hormone

Triggers cotyledons to convert starch to maltose

Maltose is used for cellular respiration

Sugar content is increased, causing more water to be absorbed

Seed coat softens and embryo emerges

Conditions for Germination

Light: For photosynthesis

Oxygen: to carry out cellular respiration

Temperature: To activate enzymes

Moisture: After heavy rain

Seed Dispersal

Propelled by plant

Carried through wind/water

Fruit (through digestive tract)

Stick to Animals

Structure of Seed

Endosperm: Nutrient rich, food for embryo

Seed Coat: Tough coat for protection

Function:provides nutrients to embryo and becomes first leaf
Dicots: Two seeded leaf
Monocots: One seed leaf
Roots
Root Structure

Vascular cylinder: Contains plants conducting tissues (xylem and phloem)

Dicot Vascular Cylinder V.S Monocot Vascular Cylinder

Endodermis: Wax layer;Separates cortex and vascular cylinder

Root Hairs: Increase SA to absorb more nutrients

Epidermis: Middle cell layer, Stores starch

Epidermis: Outer layer, Protects inside/absorb nutrients

Types of roots

Taproots: Found in dicots One thick, long, primary root in the middle Secondary roots branch from it

Fibrous Roots: Found in monocot Roots of equal size extend laterally over an area

Transport water/nutrients to stem

Some Store Food

Absorb Water/Nutrients

Anchor Plant

Stems
Growth Rings

Summer Wood: thick walls, dark colour Xylem produced slowly

Spring wood: thin walls; light colour Xylem produced rapidly

Dicots V.S Monocots

Dicot: vascular bundles arranged in a ring (vascular cambium)

Monocot: vascular bundles scattered throughout stem

Types of Stems

Woody: Hard/tough (wood); last winter

Woody System: Dicots

Bark: Everything outside Vascular cambium (protection)

Heartwood: Olderer Xylem (support)

Sapwood: Younger Xylem (transport)

Vascular cambium: Allows for thicker stem growth

Herbaceous: Green/soft; don't last winter

Function

Specialized stems

"On Ground": Grow along soil

Bulbs: Tiny, underground stems

Tubers: Underground stems

Rhizomes: store wate/food to help survive winter

Raise/support leaves/reproductive organs

Transportation of nutrients/oxygen

Types of Cell Tissue

Meristematic
Role: Plant growth; regions that are immature and continue to divide (meristems)
Lateral meristems or Cambium
Apical meristems (Tips of Roots/Shoots)
Dermal
Wxy cuticle
Thick Cell Walls
Outermost cell layers
Role: Protection
Epidermis and Dermis Cells
Vascular
Role: Transport of nutrients and support
Phloem: Thin cell walls, living at maturity
Xylem: Thick cell walls, dead at maturity
Ground
Role: Cellular growth, Storage, Support/Protection
Sclerenchyma = lignin in cell walls/dead
Collenchyma = thick walled/living
Parenchyma = thin walled/living

Plant Responses

Plant Adaptations
Salt: Roots lose water to soil through osmosis

Halophytes Response: Pump salt to stems at tip of plant; sheds tips to remove salt

Halophytes Response: Specialized glands pump salt across leaf epidermis for rain to wash away

Drought: Less water taken in than used

Response: Stomata in pits surrounded by hairs

Response: Thick cuticle and epidermis

Response: Modified leaves (spines/needles)

Response: Fleshy stem/leaves (holds water)

Flooding: Lack of oxygen for cellular respiration

Response: Partial roots above ground

Rapid Plant Movement
Increases/decreases turgor pressure of the mesophyll cells
Caused by movement of water/ions in/out of cells
Quickly Reversable
Rapid movement in response to stimulus
Tropisms
What is it

Regulated by plant hormones

Causes plant to bend to stimulus

Small Responses

Types of Tropisms

Thigmotropism: Growth of plant in response to touch

Geotropism: Growth of plant in response to gravity

Phototropism: Growth of plant in response to light