Transport in Plants Flashcards
why do plants require a transport system
to ensure all plants receive a strong supply of nutrients they require
relate the structure of xylem to its function
long continuous column made of dead tissue allowing transportation of nutrients
contain pits allowing water to move sideways between vessels
thickened with tough substance lignin providing structural support
relate the structure of phloem to its function
sieve tube elements transport sugars around the plant
companion cells designed for active transport of sugars into cells
plasmodesmata allow substances between cytoplasm of different cells
describe the structure and function of the vascular system in the roots
consists of xylem and phloem
xylem arranged in x shape to provide resistance against force
surrounded by endodermis-a water supply
describe the structure and function of the vascular system in the stem
xylem on the inside of the bundle provides support and flexibility
layer of meristem tissue that produce new xylem and phloem
describe the structure and function of vascular systems in leaves
forms midrib and veins
involved in transport and support
define transpiration
evaporation of water from leaves
consequence of gas exchange-occurs when stomata open to exchange o2 and co2
name factors that affect the rate of transpiration
increased humidity decreases rate
increased temp increases rate
increased light increases rate
increased air movement increases
waxy cuticle prevents transpiration
how can we measure transpiration rate
potometer
plant cutting placed in water filled tube containing an air bubble
calculated by measuring movement of air bubble
define water potential as a mechanism of movement in plants
tendency of water to move by osmosis from high water potential to low water potential
explain what is meant by the apoplastic pathway
method of osmosis through root hair cells
water moves through cell walls and intercellular space
only used until water reaches casparian strip
explain what is meant by the symplastic pathway
method of osmosis through root hair cells
water moves through cytoplasm via plasmodesmata
to begin water must be actively transported into cell
explain the cohesion tension theory
water molecules form hydrogen bonds with each other causing them to stick together (cohesion)
surface tension of water also creates sticking effect
as water lost through transpiration more can be drawn up in a column
give examples of adaptations of xerophytes to live in dry conditions
small/rolled leaves
densely packed mesophyll
thick waxy cuticle
stomata often closed
hairs to trap moist hair
give adaptations of hydrophytes to live in wet conditions
thin or no waxy cuticle
stomata on top of leaf and often open
wide flat leaves
air spaces for buoyancy
