Fruit Development, Seed Dispersal & Germination

Fruit Development and Structure

• Fruit is defined and composed of the exocarp, mesocarp, and endocarp, which make up the pericarp.

Methods of Seed Dispersal

• Wind dispersal uses the wind to scatter seeds (e.g., dandelions, willow herb).
• Animal dispersal relies on animals to spread seeds, often through fleshy fruits (e.g., oranges, pears).
• Water dispersal uses water to transport seeds (e.g., coconuts).
• Gravity dispersal involves seeds falling to the ground due to gravity (e.g., some beans, peas).
• Mechanical dispersal scatters seeds through explosive mechanisms (e.g., exploding seed pods).

Seed Germination

• Germination is defined, and has importance to plant life cycles.
• Germination phases include imbibition (water absorption), activation of enzymes, and radicle emergence.
• Hypogeous germination: cotyledons stay underground.
• Epigeous germination: cotyledons emerge above ground.
• Germination is affected by water, temperature, light, and oxygen availability.

Seed Dormancy and Breaking Dormancy

• Dormancy can be physical, physiological, or a combination of both (double dormancy).
• Dormancy can be broken through scarification, stratification, or after-ripening.

Seed Certification and Storage

• Four levels of seed certification exists; Breeder’s seed, Foundation seed, Registered seed, and Certified seed.
• Seed certification is important for agriculture by ensuring quality.
• Seed storage methods include cryopreservation and simple dry storage.

Cell Theory and Definition

• A cell is the basic unit of life.
• Cells can be prokaryotic or eukaryotic

Differences Between Plant and Animal Cells

• Key plant cell features include a cell wall, chloroplasts, and a large vacuole.
• Similarities between plant and animal cells include cell membranes, nuclei, cytoplasm, and mitochondria.

Cell Organelles and Their Functions

• Nucleus: stores DNA and controls cell functions.
• Mitochondria: generates energy for the cell.
• Ribosomes: produce proteins.
• Golgi Apparatus: packages and transports proteins.
• Endoplasmic Reticulum: smooth and rough types assist in protein and lipid production.
• Vacuole: stores materials, larger in plant cells.
• Lysosomes: break down waste, mainly in animal cells.
• Cytoplasm: supports and surrounds organelles.
• Cell Membrane: regulates entry and exit of materials.
• Cell Wall: provides support and protection in plant cells only.
• Chloroplasts: conduct photosynthesis in plant cells only.

Functions of the Cell Membrane

• Cell membrane acts as a "toll booth" controlling material movement in and out of the cell.
• Cell membrane composed of a phospholipid bilayer and embedded proteins.

Energy Production in Cells

• Mitochondria break down fats and carbohydrates to produce energy.
• Chloroplasts contribute to photosynthesis, converting light energy into chemical energy.

Cellular Storage and Waste Management

• Plant and animal vacuoles differ in size and function.
• Lysosomes digest cellular waste.

Water's Role in Plants

• Water is important for cell function, photosynthesis, and structural support.
• Water functions as a solvent and transport medium in plants providing nutrients.

Plant Vascular System

• Xylem transports water and minerals from roots to shoots.
• Phloem distributes photosynthetic products throughout the plant.
• Cohesion, adhesion, and capillary action helps to facilitate water movement.

Transpiration

• Transpiration is vital for water distribution to all parts of the plant.
• Cohesion-tension theory explains water movement in plants.
• Transpiration rates are affected by temperature, humidity, wind, and light intensity.
• Types of transpiration include stomatal, cuticular, and lenticular transpiration.

Regulation of Transpiration

• Stomata open and close to regulate transpiration.
• Potassium ions play a role in guard cell movement, affecting stomatal opening.
• CAM photosynthesis and adaptations in desert plants help conserve water

Mineral Requirements for Plant Growth

• Macronutrients required include nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur.
• Micronutrients include iron, manganese, zinc, copper, boron, molybdenum, nickel, and chlorine.
• Deficiency symptoms of each nutrient impact the plant health

External Leaf Morphology

• Leaf composed of the blade (lamina), petiole, veins, and midrib.
• Leaf margins, tips, and bases vary.
• Venation types include parallel, pinnate, and palmate.

Internal Leaf Structure

• Stomata regulate gas exchange
• Mesophyll layers: Palisade and spongy mesophyll.
• Chloroplasts in mesophyll cells facilitate photosynthesis.

Leaf Functions

• Leaves function for photosynthesis and energy storage.
• Leaves regulate transpiration and water levels.
• Gas exchange occurs via stomata.
• Leaves provide storage and support.

Leaf Identification and Classification

• Leaves classified to be simple or compound.
• Parallel or net venation are classification features.
• Different shapes and sizes of leaves perform different functions.

Leaf Modifications and Adaptations

• Spines on leaves in cacti act for water retention.
• Tendrils provide climbing vines support.
• Trichomes protect against herbivores.
• Aquatic leaves float on water surface.

Economic Uses of Leaves

• Leaves serve as food sources (e.g., spinach, lettuce, kale).
• Leaves also are sources to medicinal production (e.g., foxglove, St. John’s wort).
• Leaves can make fiber production (e.g., sisal rope).
• Dyes and pigments manufactured (e.g., henna, indigo).
• Used as building materials and barriers (e.g., bamboo, thatch).

Leaf Response to Environmental Factors

• Leaves wilt due to drought to conserve its water.
• Leaf abscission occurs in seasonal changes in order to prepare for different climate.
• Temperature affects leaf physiology.
• Air pollution affects leaf structure.

Root Functions

• Roots absorb water and minerals from the soil.
• Roots provide anchorage and stability to the plant.
• Roots store carbohydrates and nutrients.

Root Systems

• Taproot systems (e.g., carrots, radishes) feature a main, thick root.
• Fibrous root systems (e.g., grasses, wheat) consist of many thin roots.
• Adventitious roots (e.g., banyan tree, poison ivy) arise from stems or leaves.
• Aquatic roots (e.g., water lilies) are adapted to aquatic environments.

Regions of Root Growth

• Root cap protects the growing root tip, keeping it safe for growth.
• Region of cell division: Actively dividing cells grow new tissue.
• Region of elongation: Cells expand, increasing root length.
• Region of maturation: Cells differentiate into specialized tissues for specific functions.

Root Modifications

• Storage roots (e.g., beets, cassava) store large amounts of carbohydrates.
• Prop roots (e.g., mangroves, corn) support the plant from above ground.
• Contractile roots (e.g., dandelions, lilies) pull the plant deeper into the soil.
• Aerial roots (e.g., orchids) absorb moisture from the air.
• Buttress roots (e.g., tropical trees) provide stability in shallow soils.

Comparison of Monocot and Eudicot Roots

• Monocots have fibrous root systems and scattered vascular bundles.
• Eudicots have taproot systems and ring-like vascular bundles.

Stem Functions

• Stems support the plant structure.
• Stems transport water and nutrients (xylem & phloem).
• Stems store carbohydrates and nutrients.
• Some stems conduct photosynthesis.

Stem Structure and Growth

• External stem structures: Terminal bud, node, internode, lateral bud, lenticels, leaf scars.
• Internal stem structures: Xylem, phloem, vascular cambium, pith, cortex.
• Primary and secondary growth have diverse structures.
• Cambium increases girth.

Vascular Tissue Organization

• Monocot and Eudicot stems: different arrangements of vascular tissue.
• Vascular bundle patterns: scattered in monocots, ring-like in eudicots.
• Vascular cambium facilitates secondary growth.

Stem Classification

• Types of stems: Herbaceous vs. woody stems
• Stems diverge between monocots and eudicots
• Stems classified by Perennial and annual duration
• Stems classified by Vines and trees

Stem Modifications and Specialized Stems

• Rhizomes (e.g., ginger, iris) are horizontal underground stems.
• Stolons/runners (e.g., strawberries) are horizontal aboveground stems.
• Tubers (e.g., potatoes) are underground storage stems.
• Bulbs (e.g., onions) are underground stems with fleshy leaves.
• Corms (e.g., gladiolus) are short, vertical underground stems.
• Thorns, spines, and prickles for defense against herbivores.

Stem Adaptations and Bark

• Bark protects woody stems.
• Lenticels facilitate gas exchange.
• Tree ring formation indicates age.
• Woody plants play vital, ecological roles.

Overview of fruit structure (exocarp, mesocarp, endocarp), methods of seed dispersal (wind, animal, water, gravity, mechanical), and seed germination including phases and types.