2.3 Adaptations for transport Flashcards
Xylem
Tissue in plants conducting water and dissolved minerals upwards
Phloem
Plant tissue containing sieve tube elements and companion cells, translocating sucrose and amino acids from the leaves to the rest of the plant
Xylem vessels
Water-conducting structures in angiosperms comprising cells fused end-to-end making hollow tubes with thick, lignified cell walls (no end cell walls - hollow tube)
Tracheids
Spindle-shaped, water-conducting cells in the xylem of ferns, conifers and angiosperms.
Angiosperms
flowering plants
apoplast pathway
Pathway of water through non-living spaces between cells and in cell walls outside cell membrane
Symplast pathway
Pathway of water within cells in which molecules diffuse through cytoplasm and plasmodesmata
Vacuolar pathway
water moves from vacuole to vacuole
endodermis
a single layer of cells around the pericycle and vascular tissue of the root. Each cell has an impermeable waterproof barrier in its cell wall
Casparian strip
The impermeable band of suberin in the cell walls of endodermal cells, blocking the movement of water in the apoplast, so it moves into the cytoplasm
Adhesion
Attraction between water molecules and hydrophilic molecules in the cell walls of the xylem
Cohesion-tension theory
The theory of the mechanism by which water moves up the xylem, as a result of the cohesion and adhesion of water molecules and the tension in the water column
Systole
Contraction
Diastole
Relaxation
Bundle of His
Modified cardiac muscle fibre passing from AVN to the base of the ventricle through the septum of the heart
Purkinje fibres
Network of fibres in the wall of the ventricles
Partial pressure of oxygen
The pressure it would exert if it was the only gas present- as po2 increases, more o2 is present
Affinity
The degree to which two molecules are attracted to each other
Bohr effect
The movement of the oxygen dissociation curve to the right as a result of higher partial pressure of carbon dioxide. Haemoglobin shows a reduced affinity for oxygen
Cooperative binding
Good?
The increasing ease with haemoglobin binds its second and third oxygen molecules, as the shape of the haemoglobin molecule changes.
Good because it allows oxygen to be picked up very rapidly in the lungs
Plasma
Fluid component of the cloud comprising water and solutes; plasma = blood - cells
Tissue fluid
Plasma without the plasma proteins, forced through capillary walls, bathing cells and filling the spaces between them
tissue fluid = plasma - plasma proteins
Lymph
Fluid absorbed from between cells into lymph capillaries rather than back into capillaries
Mesophyte
Land plant adapted to neither wet nor dry environments
Xerophyte
Land plant adapted to environments with little available water e.g. marram grass
Hydrophyte
Plant adapted to living in an aquatic environment e.g water lily
Translocation
The movement of the products of photosynthesis, such as sucrose and amino acids, through phloem, from sources to sinks
Sieve tube elements
Component of phloem, lacking a nucleus, but with cellulose cell walls perforated by sieve plates, through which products of photosynthesis are transported through a plant (companion cells control them)
