Plant Phys Exam 1

Plant Physiology

Study of plant function and anatomy affecting function.

Solar Energy Harvesting

Plants capture solar energy for photosynthesis.

Sessile Growth

Plants grow toward resources due to immobility.

Structural Reinforcement

Plants support their mass with structural adaptations.

Water and Mineral Transport

Mechanisms move water/minerals to photosynthesis sites.

Transpiration Water Replacement

Plants replace water lost during transpiration.

Embryonic Development

Plants develop from embryos receiving maternal nutrients.

Sporophyte Generation

Diploid generation producing haploid spores.

Gametophyte Generation

Haploid generation producing haploid gametes.

Monoecious Plants

Produce both megaspores and microspores.

Dioecious Plants

Produce either megaspores or microspores only.

Perfect Flowers

Contain both male and female reproductive parts.

Imperfect Flowers

Contain only male or female reproductive parts.

Double Fertilization

Two sperm cells fertilize egg and form endosperm.

Endosperm

Triploid tissue supporting embryonic growth.

Antheridia

Male organ producing haploid sperm cells.

Archegonia

Female organ producing haploid egg cells.

Prothallus

Fern gametophyte containing both reproductive organs.

Growth Polarity

Vertical for stems/roots, horizontal for leaves.

Plant Cell Parts

Cytoplasm, organelles, tonoplast, plasma membrane, cell wall.

Primary Cell Wall

Thin, pectin-rich wall with cellulose and hemicellulose.

Secondary Cell Wall

Thick wall high in cellulose and lignin.

Middle Lamella

Pectin-rich layer holding multiple cells together.

Apoplast

Transport pathway outside cell membranes.

Symplast

Transport pathway within cell membranes.

Plasmodesmata

Connect living cells for solute transport.

Meristems

Sites of active cell division and growth.

Ground Tissue

Forms the body of the plant.

Vascular Tissue

Transport networks for nutrients and water.

Dermal Tissue

Protective outer layer of the plant.

Endomembrane System

Organelles involved in membrane transport.

Semiautonomous Organelles

Mitochondria and plastids with own DNA.

Nucleus Components

Nuclear envelope, pores, and nucleolus for ribosome synthesis.

Vacuole

Contains vacuolar sap, occupies 95% cell volume.

Oleosomes

Oil bodies with phospholipid monolayer.

Peroxisomes

Detoxify reactive oxygen species.

Glyoxysomes

Metabolize glyoxylate and fatty acids.

Chromoplasts

Contain carotenoids for pigment.

Leucoplasts

Non-pigmented organelles producing odors.

Amyloplasts

Store starch and detect gravity.

Plant Cytoskeleton

Microtubules and microfilaments for structure and movement.

Cell Cycle Difference

Phragmoplast forms in plants, cell plate established.

Transpiration Water Loss

Plants lose water to absorb CO2.

High specific heat

Water resists temperature changes, stabilizing environments.

High heat of vaporization

Water requires significant energy to evaporate.

High thermal conductivity

Water efficiently transfers heat between substances.

Cohesion

Water molecules stick to each other.

Adhesion

Water molecules stick to other surfaces.

Capillarity

Water rises in small tubes due to adhesion.

Diffusion

Movement from high to low concentration.

Bulk flow

Large number of molecules move together.

Fick's 1st Law

Diffusion rate depends on concentration gradient.

Osmosis

Net solvent movement across a selectively permeable membrane.

Factors affecting osmosis

Concentration, temperature, surfaces, hydrostatic pressure.

Chemical potential

Free energy associated with a substance's state.

Spontaneous change conditions

Occurs when free energy decreases.

Water potential (Ψ)

Chemical potential divided by molal volume of water.

Water potential units

Same as pressure (force/area).

Water potential components

Solute, pressure, and gravitational potential.

Pressure potential

Can be positive, negative, or zero.

Solute potential

Always negative, affects water movement.

Turgor pressure

Positive hydrostatic pressure inside plant cells.

Typical Ψ values

Herbaceous: -0.2 to -1.0 MPa; Woody: -2.5 MPa.

Höfler diagram

Shows osmolality effect on water potential.

Volumetric elastic modulus

Change in pressure potential over cell volume.

Aquaporins

Membrane proteins forming water-selective channels.

Water movement drivers

Water moves from low to high solute concentration.

Soil texture

Influences water movement via pore size differences.

Pore sizes

Sand has large pores; clay has small pores.

Osmotic potential

Typically -0.02MPa due to low solute concentration.

Pressure potential

Close to zero in wet soils; negative when dry.

Gravitational potential

0.1MPa/10m, affects drainage, not uptake.

Radius of curvature

Increases as soil dries, decreasing water potential.

Water movement driver

Bulk flow from pressure gradients due to roots.

Rate of flow factors

Affected by pressure potential change and conductivity.

Soil hydraulic conductivity

Higher in sandy soils; lower in dry soils.

Root hairs

Main site of water absorption in roots.

Root anatomy parts

Includes meristematic region, cortex, and stele.

Apoplast pathway

Water moves outside of cell walls.

Symplast pathway

Water moves via plasmodesmata between cells.

Transmembrane pathway

Water enters and exits cells on opposite sides.

Endodermis function

Forces water and solutes into cells via symplast.

Casparian strips

Suberin barriers preventing apoplast water movement.

Pericycle function

Initiates formation of lateral roots.

Xylem and phloem

Transport solutes and nutrients in vascular tissue.

Aquaporins role

Regulate water permeability in roots under stress.

Root pressure

Caused by low transpiration, drives water into xylem.

Guttation

Droplets of sap from leaves due to xylem pressure.

Tracheids

Xylem elements connecting via bordered pits.

Vessel Elements

Angiosperm xylem components with perforated plates.

Bordered Pits

Control embolisms by sealing tracheids during pressure changes.

Poiseuille's Law

Predicts flow rate based on vessel diameter.

Transpiration

Main force driving sap ascent in plants.

Cohesion-Tension Theory

Explains water movement through cohesion and tension.

Hydraulic Resistance

Resistance to water flow in plant tissues.

Embolism Repair

New xylem conduits or root pressure fills embolisms.

Evaporation

Water loss from mesophyll cells to atmosphere.

Diffusion

Movement of water vapor through stomates.

Vein Density

Higher density reduces hydraulic resistance in leaves.

Stomatal Resistance (rs)

Resistance to CO2 diffusion through stomatal pores.