SBI3U Plants

Plantae Characteristics

* Eukaryotic
* Multicellular
* Photosynthetic
* Cell walls contain cellulose
* Sexual or asexual reproduction
* Autotrophic

Vascular and Non-Vascular Plants

* Vascular Plants
* Have vascular vessels to transport food and water
* Examples: Flowers and trees
* Non-Vascular Plants
* Small, simple plants without a vascular system
* Cannot transport food or water very far
* Lack roots, have rhizoids
* Commonly found in moist environments
* Reproduce sexually by creating single-celled spores or asexually by vegetative propagation
* Examples: Mosses, liverworts, and hornworts

Plants with Seeds and Seedless Plants

* Plants with Seeds
* Allow plants to reproduce sexually without needing water and provide protection
* Appeared about 280 million years ago
* Divided into 2 groups - Angiosperms and Gymnosperms
* Seedless Plants
* Do not produce seeds, are dispersed by windblown spores or by water
* Formed first forests 350 million years ago
* Examples: Ferns, whisk ferns, club mosses, and horsetails

Angiosperms and Gymnosperms

* Angiosperms
* Flower producing plants
* The mature seed is surrounded by an ovule (e.g. apple)
* Hardwoods
* Trees have broad leaves that usually change colour and die every autumn
* Gymnosperms
* AKA naked seeds
* Non-flower producing plants
* The seed is not encased by an ovule (e.g. pine cone)
* Softwoods
* Usually needles stay green throughout the year

The Seed

3 Primary Parts:

* Embryo
* The young multicellular organism before it emerges from the seed
* Endosperm
* A source of stored food (primarily starches)
* Seed Coat
* Protective layers that encase the seed

Cotyledon

* An embryonic leaf in a seed bearing plant
* The first leaves to appear from a germinating seed
* Single Cotyledon Embryo
* Monocot, or Monocotyledonous Plant
* 2 Cotyledon Embryo
* Dicot, or Dicotyledonous Plant

Monocots and Dicots

* Monocots
* 1 cotyledon
* Cotyledon is thin, small and lacks food materials
* Endosperm present and stores food
* Dicots
* 2 cotyledons
* Cotyledons are fleshy and store food
* Endosperm absent
* Key Differences
* Monocots: 1 cotyledon
* Dicots: 2 cotyledons
* Monocots: Energy stored in endosperm
* Dicots: Food stored in cotyledons

Monocot and Dicot Characteristics

* Monocots
* Vascular Tissue: Scattered
* Roots: Fibrous
* Pollen Grain: 1 Opening
* Flower Petals: Multiples of 3
* Cotyledons: 1
* Leaf Venation: Parallel
* Dicots
* Vascular Tissue: Arranged in a ring
* Roots: Taproot
* Pollen Grain: 3 Openings
* Flower Petals: Groups of 4 or 5
* Cotyledons: 2
* Leaf Venation: Net-like

Word and Chemical Equation of Photosynthesis

* Word Equation
* water + carbon dioxide + sunlight → glucose + oxygen
* Chemical Equation
* H2O + CO2 → C6H12O6 + O2

Overview of Photosynthesis

* Occurs in the chloroplast
* Divided into 2 stages
* Light Reactions
* Light-Dependent Cycle
* Calvin Cycle
* Light-Independent Cycle
* Dark Cycle

Light Reactions

* Takes place in the thylakoid membrane
* Uses solar energy to:
* Split water into hydrogen ions, electrons, and oxygen
* Excite electrons within chlorophyll to set off a series of reactions that create high energy compounds

Calvin Cycle

* Takes place within stroma in chloroplasts
* Uses high energy compounds from light reactions to drive the cycle
* Carbon dioxide combines with intermediate compounds to form glucose

Macromolecules

* Required in large amounts
* **Nitrogen (N) - component of proteins, RNA & DNA**
* **Phosphorous (P) - component of RNA & DNA**
* **Potassium (K) - controls stomata, water intake**
* Calcium (Ca) - development and function of cell walls
* Magnesium (Mg) - component of chlorophyll

Fertilizers

* Two types:
* Organic: from living sources (e.g. manure, bone meal, and compost)
* Inorganic: produced chemically

Percent Composition

* 10-10-20
* Refers to the percentage of N, P, and K
* In general:
* N promotes green growth
* P promotes root and flower growth
* K promotes hardiness (e.g. drought resistance)

Micromolecules

* Required in small amounts
* Iron (Fe)
* Chlorophyll structure and cell respiration
* Zinc (Zn)
* Regulation of plant growth and function of chloroplasts
* Copper (Cu)
* Reproduction, root metabolism, and cell respiration

Auxins

* Produced in stem, root tip, and buds
* Promotes elongation (encourages growth)
* Causes the plant to grow tall and straight
* Bends stem towards light (+ phototropism)
* Downward root growth away from light (- phototropism)
* Prevents leaves from falling

Gibberellins

* Promotes seed germination
* Promotes stem and root growth
* Promotes leaf growth
* Promotes flower development
* Increases fruit size
* They are not produced in the stem tip

Cytokinins

* Promotes division and differentiation of cells
* Found in growing areas of plant
* Promotes seed germination
* Promotes flowering
* Prevents aging

Ethylene

* Ripens fruit, prompts leaves to change colour, and petals to die off
* Higher temperatures trigger the production of ethylene
* The gas is able to travel from cell to cell and plant to plant

Abscisic Acid

* Inhibits growth
* Induces dormancy
* Causes leaves to fall
* Involved in opening and closing of stomata as leaves wilt

Tropisms

* Plants also change their growth patterns in response to external stimuli
* Changes in the environment around a plant affect its growth
* These responses are called tropisms and are controlled by hormones
* Positive tropism = growth with/towards stimuli
* Negative tropism = growth away from stimuli

Phototropism

* Stems grow toward light (Positive)
* Roots grow away from light (Negative)

Gravitropism/Geotropism

* Roots grow with gravity (Positive)
* Stems grow against gravity (Negative)

Thigmotropism

Growth in response to touch (e.g. vines)

Stem Structure

* Stems are one of two main structures in vascular plants (the other is the root)
* Stems are made up of nodes and internodes
* Nodes hold leaves and buds which grow into branches
* Internodes are the spaces between nodes

Stem Functions

* Support for leaves, flowers, and fruits
* Transport of fluids between the roots and the shoots in the xylem and the phloem
* Storage of nutrients
* Production of new living tissue
* Normal lifespan of plant cells: one-three years
* Meristems generate new living tissue

Stem Tissues

There are 3 main tissues:

* Dermal Tissue
* Outer surface of stem
* Used to waterproof, protect, and control gas exchange
* Ground Tissue
* AKA fundamental tissue
* Performs photosynthesis
* Functions as storage and support
* Vascular Tissue
* Provides long distance transport and structural support

Herbaceous Dicots

* Stems with primary growth
* Pith (ground tissue) in the centre
* Vascular bundles are arranged in a distinct ring around the outside
* Epidermis and cuticle protect the outside of the stem
* Limited height due to weight support

Woody Dicots

* Secondary growth thickens stem
* Vascular cambium cell division
* Secondary xylem (inside) and phloem (outside)
* Cortex and epidermis destroyed
* Cork cambium develops cork cells
* Secondary xylem becomes wood (structural support)

Tree Rings

* Cork cambium stops after growing season
* Growth ring formed
* Spring: More xylem, larger cells, less dense wood
* Fall: Fewer, smaller xylem, dense wood (visible ring)

Monocot Stems

* Vascular bundles scattered (screaming faces)
* Rare secondary growth
* Seldom woody
* Exceptions: Palm trees and bamboos

Cell Types of Vascular Tissue

* Xylem: Tracheids and Vessel Elements
* Thick walled
* Dead at maturity
* Rich in lignin for strength
* Non-living cells
* Transport water from roots to leaves
* Phloem: Sieve Tubes and Companion Cells
* Live at maturity
* Contain cytoplasm
* Living cells
* Transport sugar from leaves to roots
* Xylem and phloem form long, continuous tubes

Plant Structure

* Root System
* Shoot System
* Stem
* Leaves
* Flowers

Root System Functions

1. Anchors
2. Absorption (water and nutrients)
3. Transportation
4. Storage

Specialized Root Growth

* Meristem: new cell growth
* Root cap: cells produce mucus-like substance that lubricates root movement in soil
* Root hairs: Increase the surface area for absorption of water and nutrients

Meristem/Meristematic Cells

* Unspecialized cells that divide and differentiate into specialized tissue

Root Structure

* Epidermis
* Root hairs increase absorption of water and minerals
* Cortex
* Transports water and minerals from epidermis to vascular cylinder
* Storage of food
* Endodermis is the inner waxy layer
* Vascular Cylinder
* Xylem transports water and minerals from the roots to the leaves
* Phloem transports sugars from the leaves to the roots

Root Types

* Fibrous roots (Monocots)
* Ex. Grasses, wheats
* Taproots (Dicots)
* Ex. Dandelions, carrots
* Adventitious roots (Monocots and Dicots)
* Ex. Rice, ivy, strawberries

Root Hairs

* Osmosis: water absorption process
* Root cells: hypertonic to soil
* Passive entry via osmosis
* Thin root cell walls
* Large surface area
* Root depth: soil moisture dependent
* Hypertonic: Higher solute concentration than adjacent solutions

Cross Section of Monocot and Dicot Roots

* Monocots
* Separate strands of xylem and phloem
* Dicots
* Xylem is x-shaped
* Separate strands of phloem

Structure and Function (Leaves)

* Function
* Photosynthesis
* Uses carbon dioxide
* Produces water and glucose
* Structure
* Designed to capture maximum light and minimize water loss

Leaf Tissues

The leaf is composed of 3 main tissues


1. Dermal Tissues
2. Vascular Tissues
3. Ground Tissues

Dermal Tissues

* Epidermis: Protective outer layer composed of polygonal cells
* Defends against injuries and foreign organisms
* Secretes waxy substance
* Forms cuticle on leaf’s surface
* Cuticle unique to terrestrial plants
* Aids in water retention

Stomata and Guard Cells

* Lower epidermis of leaf
* Microscopic pores: Stomata
* Stoma: Small Opening
* Pair of specialized cells: Guard Cells

Opening and Closing of Stomata

* Guard cells regulate stomata
* Control gas exchange and transpiration
* High solute: water in, guard cells swell. stomata open (day)
* Low solute: water out, stomata close (night)
* Environmental factors influence behaviour
* Hot, dry weather: guard cells close stomata to reduce evaporation

Vascular Tissues

* Leaf connected to the plant’s vascular structure
* Xylem and phloem in stem, branch for leaf supply
* Veins in leaves consist of xylem and phloem
* Vascular components extend through the mesophyll
* Close proximity for photosynthesis

Ground Tissues

* Ground tissue in mesophyll
* Between the upper and lower endodermal layers
* Predominant cells: parenchyma cells
* Contain chloroplasts for photosynthesis
* Mesophyll layers: palisade parenchyma, spongy parenchyma

Monocot and Dicot leaves

* Monocots
* Dumbbell-shaped guard cells
* Parallel veins
* No mesophyll differentiation
* Dicots
* Kidney-shaped guard cells
* Reticulate (branched) veins
* Differentiated mesophyll: palisade, spongy

Water Transport (Xylem)

* Root hairs perform absorption of minerals
* Active transport is the method of mineral absorption
* Energy is needed for active transport
* Energy is produced by glucose stored in the roots through cellular respiration
* Mineral Transport Sequence: soil water, epidermis, cortex, endodermis, xylem
* Hypertonic condition is created due to active transport
* Water enters passively due to osmosis
* Root pressure propels water and minerals up the xylem

Leaf Pull (Transpiration Pull)

* Evaporation of water “pulls” on adjacent water molecules
* Moves up stem via adhesion and cohesion

Bernoulli’s Principle

* Breeze blowing by creates low pressure
* Water and minerals in root in an area of high pressure
* Movement from high pressure towards low pressure

Food (Sugar) Transport

* Sugars actively transported from leaves into xylem
* Active transport against concentration gradient requires ATP
* Hypertonic condition is set up in the phloem relative to the xylem
* Water rushes into phloem passively via osmosis
* High pressure area created in the phloem relative to the roots
* Phloem sap pushed down and stored in roots

Seed Germination

* Radicle pushes down to form roots
* Hypocotyl pushes up to form stem
* Epicotyl and Cotyledon grow upwards to form leaves
* Seeds require heat and moisture for germination
* Gibberellin hormone is released
* Starches are broken down into simple sugars to provide energy for growing embryo
* Water absorbed into seeds and seed coat cracks
* Oxygen diffuses into seeds for gas exchange
* Radicle emerges and becomes a root
* Hypocotyl emerges and becomes a stem
* Cotyledons from temporary leaves
* True leaves develop and plant matures

Plant Adaptations

* Desert
* Wetlands
* Fire-prone areas
* Extreme cold
* Nutrient-poor soil
* Shade

Desert

* Condition
* Very dry and often very hot or very cold
* A lot of direct sunlight
* Sandy or rocky soil that is unable to hold much water
* Adaptations
* Hold water in stems
* No leaves or small ,seasonal leaves to reduce water loss
* Photosynthetic green stems
* Long root systems
* Short life cycle for swift reproduction
* Germination is initiated by rainfall
* Hairy leaves to minimize water loss
* Leaf orientation adjustments to reduce water loss
* Spines for animal deterrence
* Waxy coating on stem/leaves to limit water loss
* Slow growth rate to conserve energy and water

Wetlands

* Conditions
* Water currents
* Unstable surface for anchorage
* Reduced access to sunlight
* Adaptations
* Floating leaves with stomata on upper surface
* Chlorophyll on upper epidermis for photosynthesis
* Hollow stem for buoyancy and diffusion of gases
* Floating seeds

Fire-prone areas

* Conditions
* Acidic Soil
* Extreme heat
* Adaptations
* Ashes neutralize acidic soil
* Extreme heat opens tough seed coats (e.g. Jack Pine)
* Few competitors

Extreme Cold

* Conditions
* Short, cool summers and long, severe winters
* Permanently frozen soil sublayer
* Poor drainage and slow evaporation
* Little precipitation
* Adaptations
* Short, low-growing plants due to nutrient scarcity
* Plants are dark-coloured to maximize solar heat absorption
* Plants have hair, grow in clumps, and/or have dish-like flowers to for heat retention

Nutrient-poor Soil

* Carnivorous
* Capture, kill, and digest insects
* Acquire N, P, and K
* Ex. Venus fly trap, pitcher plants
* Parasitic
* Absorb water, minerals, and sugars from xylem and phloem
* Ex. mistletoe

Shade

* Early bloom
* Rapid growth
* Have broad, thin leaves to catch more sunlight
* Adapted to make more use of soil nutrients as they get less nutrients from the Sun

Gymnosperms

* Conifers are the most numerous
* Reproductive Structures
* Pollen Cones (Male)
* Seed Cones (Female)
* Pollen is dispersed by wind
* Pollen produces sperm when contact is made with seed cone
* Sperm fertilizes the ovules
* Zygotes grow into seeds

Angiosperms

* Reproduce sexually
* Flower contains reproductive structures
* Process of reproduction involves 3 steps:


1. Pollination and Fertilization
2. Seed Dispersal
3. Germination

Structure of Flowers

* Male Floral Structures = Stamen
* Female Floral Structures = Pistil (Carpel)

Structures and Functions

* Sepal
* Protects the flower until it opens
* Flowers
* Attract animal pollinators to the flower

Stamen (Male)

* Anther
* Produces pollen
* Contains sperm
* Filament
* Holds the anther above the flower
* Not present in all flowers

Pistil/Carpel (Female)

* Stigma
* Where pollen attaches
* Style
* Holds the stigma above the flower
* Contains pollen tube which pollen goes down to fertilize eggs
* Ovaries
* Produce egg inside ovule
* Ovule becomes a seed
* Ovary develops into a fruit
* Receptacle
* Attaches the flower to the pedicel (or stalk)
* Pedicel
* Lifts flower above leaves for access to pollinators

Pollination

* Pollen released from plants, adapted for egg distribution via multiple methods
* Wind
* Water
* Animals (e.g. insects and birds)
* Algae: unique plant with water-distributed pollen
* Wind-distributed pollen characteristics
* Winged for assistance in travel
* Produced in large volumes due to high likelihood of missing target

Why are flowers bright colours and smell sweet?

* Flowers use various methods to attract pollen carriers
* Bright colours
* Sweet smells
* Nectar production
* Colour-specific attractions
* Bees: Yellow, white, and purple flowers
* Hummingbirds: Pink, orange, and red flowers

Fertilization

* Pollen uses enzymes to navigate
* Route: Down pollen tube, through the stigma, to ovules
* Fertilization process
* Each ovule is fertilized with a sperm from pollen
* Sperm (1N) and egg (1N) fusion
* Result: Zygote (2N)
* Additional sperm (1N) fuses with a polar nuclei (2N)
* Result: Endosperm (3N)
* Endosperm function: feed developing zygote

Seed Dispersal

* Wind (e.g. dandelions, maple key0
* Water (e.g. coconut)
* Animals externally (e.g. burdock)
* Animals internally (e.g. ingested fruit seeds)