Transport in plants Flashcards
The transport of minerals over longer distances through vascular system is called
Translocation
The direction of transport of water and minerals through xylem is
unidirectional
The direction of transport of organic compounds or withdrawal of nutrients during senescence is
multidirectional
Passive transport of molecules over short distances occur by
Diffusion
Gaseous movement within the plant body occurs only through
diffusion
Diffusion rate is affected by membrane permeability, temperature, pressure and ______
Gradient of concentation
Hydrophilic substances pass through the membrane by
facilitated diffusion
The pre-requisite for facilitated transport is the presence of carrier protein and ____
Concentration gradient
Facilitated diffusion is accomplished with the help of _____ proteins
Carrier
The diffusion in which proteins move substances across the membrane without the expenditure of energy is called
facilitated diffusion
Facilitated diffusion is very specific and is sensitive to ____ which react with protein side chains
Inhibitors
The protein that form large pores in the outer membranes of the membranes of the plastids, mitochondria and some bacteria allowing molecules up to the size of small proteins to pass through are called ____
Porins
Water channels are composed of ___ different types of aquaporins
Eight
The type of facilitated transport in which two molecules move across the membrane in same direction is called
symport
The type of facilitated transport in which two molecules move across the membrane in opposite directions is called
antiport
The type of facilitated transport in which a molecule across a membrane independent of other molecules is known as
Uniport
The transport in which energy is used to transport molecules against concentration gradient is called
active transport
The proteins which use energy to carry substances across the cell membrane are known as
pumps
Pumps are sensitive to inhibitors that react with
protein side chains
The transport which requires a carrier but no energy is referred to as
facilitated diffusion
The mode of transport which does not require any energy and occurs only along the gradient
diffusion
The medium required for dissolution of most of the substances in plants is
water
Water taken yp by terrestrial plants get lost to air by the process called
transpiration
Solute potential and pressure potential are major determinants of ____ potential
water potential
Highest water potential is possessed by
pure water
Water potential is denoted by
Psi
Water potential of solutions is always ____ than that of pure water
less
The lowering of water potential due to dissolution of solute is called
solute potential
For a solution at atmospheric pressure, solute potential is equivalent to _____
water potential
If a pressure greater than atmospheric pressure is applied to pure water, its water potential ____
increases
Turgidity ____ the pressure potential
Increases
Negative pressure potential or tension in which vascular tissue plays a major role in water transport up a stem?
water column in the xylem
The part of the cell that mainly contributes to the solute potential of cell is
central vacuole
The membrane of vacuole is called
tonoplast
Diffusion of water across a selectively permeable membrane is called
Osmosis
The direction and rate of osmosis depends on both the gradient of _____ and _____
pressure and concentration
Osmotic potential is eual to osmotic pressure but with ____ sign
negative
External solution is said to be ____ when it balances the osmotic presure of the cytoplasm
Isotonic
If the external solution is more dilute than the cytoplasm, it is called
Hypotonic
Cell swell up when placed in
Hypotonic solution
When placed in hypertonic solution, cells ____
shrink
The process of water moving out of the cell and cell membrane getting shrinked from cell wall is called
Plasmolysis
During plasmolysis, water is first lost from the ____
cytoplasm
The phenomenon of cell shrinking away when placed in ___ solution is called plasmolysis
hypertonic
There is no net flow of water towards inside or outside when the cell is placed in an ___ solution
Isotonic
When the outer and inner environment of cell are in equilibrium, the cell is said to be
Flaccid
Water while diffusing into a cell causes cytoplasm to build up a pressure against wall, called
Turgor pressure
The tugor pressure exerted by protoplasm due to entry of water against rigid cell walls is called ___ pressure
pressure potential
The pressure responsible for enlargement and extension growth of cells is
Turgor pressure
The special type of diffusion when water is absorbed by solids or colloids causing them to increase in volume is called
Imbibition
The absorption of water by seeds is an example of
Imbibition
The movement of water during imbibition is _____ the concentration gradient
along
Movement of water in plants usually occurs through
Xylem
The system by which water, minerals and food are transported in plants across long distances is called
Bulk/ mass flow system
Bulk flow in plants is usually achieved through _____ gradients
Hydrostatic pressure
The bulk movement of substances through the vascular tissues of plants is called
Translocation
The vascular tissues associated with translocation of water, mineral salts, some organic nitrogen and hormones from roots to aerial parts of the plant is
Xylem
Translcation of organic and inorganic solutes occur mainly from leaves to other parts of plant through
Phloem
The responsibility of absorption of water and minerals from soil through roots is of
Root hairs
Root hairs are thin - walled slender extensions of root _____ cells
Epidermal
Absorption of minerals and water in root occur through the process of
Diffusion
The two pathways involved in movement of water into root layers after absorption are
Apoplast and symplast pathway
The apoplast system is continous throughout the plant except at ______
casparian strips
The movement of water which occurs through intercellular spaces and walls of cells is
Apoplastic
The pathway for movement of water which does not involve crossing the cell membrane is called
Apoplast pathway
The _____ does not provide any barrier to water movement and water movement is through ___
apoplast; mass flow
Mass flow of water in apoplastic movement is due to which two properties of water?
Cohensive and adhesive
The symplast system is the system of interconnected _____
Protoplast
Intercellular movement of water in symplastic pathway occurs through _____
Plasmodesmata
The movement of water aided by cytoplasmic streaming is called
Symplastic movement
Majority of water flow in roots occurs via which pathway?
Apoplast
Endodermis is impervious to water because of presence of suberised matrix called
Casparian strip
The movement of water in endodermis is always _____
Symplastic
In young roots, xylem vessels and tracheids are a part of _____
Apoplast
A symbiotic association of root system with a fungus is called
Mycorrhiza
The part of fungus that absorbs mineral ions and water from soil is
Hyphae
In mycorrhiza, much larger volume of minerals and water are provided to the roots by
Fungus
Sugars and N-containing compounds are provided by ____ to mycorrhizae
Roots
Name a plant having obligate relationship with mycorrhizae
Pinus
Pinus seeds cannot germinate and establish without the presence of which association ?
Mycorrhizae
The positive pressure responsible for pushing up water to small heights in stem is called
Root pressure
Water loss from plants in liquid phase is called
Guttation
Majority of water transport occurs due to pressure generated in plants by _______
Transpiratory pull
Cohensin-tension-transpiration pull model states that the driving force for water movement is ____
Transpiration
The loss of water through stomata in leaves by evaporation is called
Transpiration
Transpiration mainly occurs through _____
Stomata
The opening and closing of sromata is due to change in tugidity of _____ cells
gaurd
Thickness and elasticity are characterised of which wall of gaurd cells?
Inner wall
Cellulose microfibrils are oreintated ____ rather than ______ making it easier for stoma to open
Radialy; longitudinal
During water stress, stoma closes because gaurd cells become _____
flaccid
The type of leaf exhibiting more number of stomata on lower side is called
Dorsiventral leaf
The leaf exhibitingequal number of stomata on both surfaces is called
Isobilateral leaf
Dorsiventral leaf is a characteristic feature of which plants?
Dicot plants
The leaf possessed by monocot planrs is
Isobilateral layer
Cohension, adhension and surface tension are the factors affecting
Transpiration pull
Mutual attraction between water molecules is called
Cohension
Adhension refers to the attraction of water molecules to
Polar surfaces
The phenomenon of water molecules getting attracted more to each other in liquid phase more than to water in gas phase is termed as
Surface tension
Cohension, adhension and surface tension provides ____ strength and capillarity to water
Higher tensile
Small diameters of tracheids and vessel elements provide high ____
Capillarity
Transpirationsl pull is created due to lower concentration of water vapour in ______
Atmosphere
The transpirational pull for absorption and transport in plants is created by _____
transpiration
Water for photosynthesis is supplied by the process of
Transiration
Evaporative cooling is due to?
Transpiration
The evolution of which photosynthetic system has maximised the availability of carbon dioxide minimising water loss?
C4 pathway
C4 plants are twice as efficient as C3 plants in terms of ____
CO2 fixation
The minerals which are present in lower concebtration in soil than roots are absorbed by
active transport
The process of osmosis keeps going due to water potential gradient in roots which is maintained due to?
Active uptake of ions
The quantity and type of solutes that reach xylem is regulated by transport proteins of which cells?
Endodermal cells
Root endodermis has ability to actively transport ions in one direction only due to the presence of _____
Suberin
After ions have reached xylem, further transport occurs through
Transpirational stream
Unloading of mineralions occur at the fine vein endings through __ and ___ uptake by growing regions of plant
diffusion and active
Structureal components like ___ are not remobilised before senescence
Calcium
Four most readily mobilised elements in plants are
phosphorous, sulphur, nitrogen and potassium
Most of the nitrogenin plants is transported in ____ form
organic
The vascular issue which transports sucrose in plants is _____
phloem
The direction of movement in phloem is
Bi-directional
The two main components of phloem sap are
Water and sucrose
Phloem sap is mainly water and sucrose, but other sugars, hormones and amino acids are transported or translocated through _____
Phloem
The accepted mechanism for translocation of sugars from source to sink is
Pressure flow hyphothesis
Glucose prepared by photosynthesis is converted into _____
sucrose
Hypertonic condition created in phloem leads to transport of water from adjacent xylem to phloem by the process of
Osmosis
The process of loading sucrose at sorce generate ______ condition in phloem
Hypertonic
The type of transport which mobilises sugars in plants is
Active transport
Phloem tissue is composed of ____, which form long columns with holes in their end walls
Sieve tube cells
The water from phloem returns to xylem due to loss of ___ in it
Solute
The expeiment which was used to identify the tissues through which food transport is _____
Gridling
Plants need to move molecules over very long diatances, much more than animals do; they alsodo not have a ____ system in place
Circulatory
Water taken up by the roots has to reach all parts of the plant, up to the very tip of the ____
growing stem
The _____ or food synthesised by the leaves have also to be moved to all parts including the root tips embedded deep inside the soil
photosynthesis
