9.1 Transport in the xylem of plants

xylem

specialised vascular tissue, composed of many cell types, that brings water to the leaves

transpiration

evaporation of water from the leaves of a plant

stomata

small openings in the leaf epidermis that allow gas exchange

draw a plan diagram to show major structures of a generalised leaf

cuticle

layer protects the plant against
water loss and insect invasion

epidermis

the outermost layer (if cuticle not present) that protects the plant

vascular tissue

specialized tissue in plants that carries water and nutrients

phloem

specialized vascular tissue that carries the products of photosynthesis to the rest of the plant.

vascular bundles

veins that house both xylem and phloem vessels

palisade mesophyll

a densely packed region of cylindrical cells that occur in the upper portion of the leaf which contain large numbers of chloroplasts to carry out photosynthesis

spongy mesophyll

loosely packed cells with few chloroplasts and many air spaces which provide gas exchange surfaces

guard cells

specialised cells in epidermis that control the opening and closing of the stomata

transpiration stream

movement of water through a plant from the roots to the leaves as a result of the loss of water by evaporation from the surface of the leaves

tracheids

components of xylem tissue;
dead cells that taper at the ends and connect to one another to form a continuous column

vessel elements

components of xylem tissue;
dead cells with thick, lignified walls. They are attached end to end to form continuous columns and have perforations, allowing water to move freely up the plant

lignin

a complex organic compound that greatly strengthens
the cell walls of vascular plants (It also waterproofs plant parts and adds protection against pathogens)

turgor pressure

pressure inside of a cell as a cell pushes itself against the cell wall

abscisic acid

A plant hormone that brings stomatal closing, among other effects

cohesion-tension theory

water is pulled up the xylem vessels by the cohesive force between the water molecules and the adhesion of the water molecules to the rigid vessel walls

root hairs

specialised epidermal structures that increase the surface area over which water and mineral ions can be absorbed

root cap

protects the apical meristem during primary growth of the root through the soil

apical meristem

group of undifferentiated cells that divide to produce increased length of stems and roots

lateral meristem

undifferentiated cells that occur in stem tissue and allow for growth in width.

fungal hyphae

fungal filaments that absorb minerals from the soil and exchange with sugars from the plant (mutualism)

mass flow

some minerals dissolved in water move into the roots as water moves into the outer root cells via osmosis

proton pump

used to transport mineral ions and solutes such as potassium ions, nitrogen-based ions, and even simple sugars

xerophytes

plants adapted to arid climates

Halophytes

plants adapted to grow in water with high levels of salinity

CAM plants

plants close their stomata during the day, collect CO2 at night, and store the CO2 in the form of acids until it is needed during the day for photosynthesis

C4 plants

a plant in which the Calvin cycle is preceded by reactions that incorporate CO2 into a four-carbon compound, the end product of which supplies CO2 for the Calvin cycle.

potometer

used to measure transpiration rates