Chapter 11 : Transport in Plants

Water molecule is very polar. Polar end of molecule attracts opposite
charges on another water molecule (acts like magnet). How will you
explain this property of water with reference to upward movement of
water? Comment on the upward movement of water given the
intermolecular hydrogen bonding in water.

The radio labelled carbon in carbon dioxide supplied to potato plants
in an experiment was seen in the tuber eventually. Trace the movement
of the labelled carbon dioxide.

Halophytes may show precell pressure very much higher than
atmospheric pressure. Explain how this can happen?

Which of these is a semipermeable membrane (S.P) and which is selectively
permeable (S.L)
a. Animal Bladder
b. Plasmalemma
c. Tonoplast
d. Parchment membrane
e. Egg membrane

Plants show temporary and permanent wilting. Differentiate between
the two. Do any of them indicate the water status of the soil?

Minerals are present in the soil in sufficient amounts. Do plants need to
adjust the types of solutes that reach the xylem? Which molecules help
to adjust this? How do plants regulate the type and quantity of solutes
that reach xylem?

Define Uniport, Symport and Antiport. Do they require energy?

Explain the mass flow hypothesis of transport in phloem.

How is facilitated diffusion different from diffusion?

Differentiate between diffusion and translocation in plants.

We know that plants are harmed by excess water. But plants survive
under flooded condition. How are they able to manage excess water?

ABA (Abscisic acid) is called a stress hormone.
a. How does this hormone overcome stress conditions?
b. From where does this hormone get released in leaves?

What are ‘aquaporins’? How does presence of aquaporins affect osmosis?

What is the chemical composition of xylem and phloem sap?

Salt is applied to tennis lawns to kill weeds. How does salting tennis
lawns help in killing of weeds without affecting the grass?

Sugar crystals do not dissolve easily in ice cold water. Explain.

When a freshly collected Spirogyra filament is kept in a 10% potassium
nitrate solution, it is observed that the protoplasm shrinks in size:
a. What is this phenomenon called?
b. What will happen if the filament is replaced in distilled water?

Keep some freshly cut flowers in a solution of food colour. Wait for
sometime for the dye to rise in the flower, when the stem of the flower is
held up in light, coloured strands can be seen inside. Can this experiment
demonstrate which tissue is conducting water up the stem?

Will the ascent of sap be possible without the cohesion and adhesion of
the water molecules? Explain.

How can plants be grown under limited water supply without
compromising on metabolic activities?

Various types of transport mechanisms are needed to fulfil the mineral
requirements of a plant. Why are they not fulfilled by diffusion alone?

In a girdled plant, when water is supplied to the leaves above the girdle,
leaves may remain green for sometime then wilt and ultimately die. What
does it indicate?

Cut pieces of beetroot do not leave colour in cold water but do so in hot
water. Explain.

How is it that the intracellular levels of K+ are higher than extracellular
levels in animal cells?

Water is indispensable for life. What properties of water make it useful
for all biological processes on the earth?

Do different species of plants growing in the same area show the same
rate of transpiration at a particular time? Justify your answer.

From your knowledge of physiology can you think of some method of
increasing the life of cut plants in a vase?

If one wants to find minerals and in the form they are mobilised in the
plant, how will an analysis of the exudate help?

Minerals absorbed by the roots travel up the xylem. How do they reach
the parts where they are needed most? Do all the parts of the plant get
the same amount of the minerals?

Correct the statements
a. Cells shrink in hypotonic solutions and swell in hypertonic
solutions.
b. Imbibition is a special type of diffusion when water is absorbed by
living cells.
c. Most of the water flow in the roots occurs via the symplast.

Identify a type of molecular movement which is highly selective and
requires special membrane proteins, but does not require energy.

A gardener forgot to water a potted plant for a day during summer,
what will happen to the plant? Do you think it is reversible? If yes, how?

Describe briefly the three physical properties of water which helps in
ascent of water in xylem.

Transpiration is a necessary evil in plants. Explain.

Differentiate between guttation and transpiration.

Give the location of casparian strip and explain its role in the water
movement.

How does most of the water moves within the root?

Differentiate between Apoplast and Symplast pathways of water
movement. Which of these would need active transport?

An onion peel was taken and
a. Placed in salt solution for five minutes.
b. After that it was placed in distilled water.
When seen under the microscope what would be observed in a
and b?

Define water potential and solute potential.

Movement of substances in xylem is unidirectional while in phloem it is
bidirectional. Explain.

The plant cell cytoplasm is surrounded by both cell wall and cell
membrane. The specificity of transport of substances are mostly across
the cell membrane, because _________________.

Water moves up against gravity and even for a tree of 20m height, the tip
receives water within two hours. The most important physiological
phenomenon which is responsible for the upward movement of water is
_______________________.

Absorption of water from soil by dry seeds increases the _____________,
thus helping seedlings to come out of soil

A flowering plant is planted in an earthen pot and irrigated. Urea is
added to make the plant grow faster, but after some time the plant dies.
This may be due to _______________ .

Osmosis is a special kind of diffusion, in which water diffuses across the
cell membrane. The rate and direction of osmosis depends upon
both ______________.

In a passive transport across a membrane, when two protein molecules
move in opposite direction and independent of each other, it is called as
___________.

Smaller, lipid soluble molecules diffuse faster through cell membrane,
but the movement of hydrophilic substances are facilitated by certain
transporters which are chemically ____________.

Define transpiration? Why is it useful? Mention any three environmental
factors that affect the transpiration?

How is opening & closing of stomata controlled?

Describe the plant cell as an osmotic system?

Distinguishes between imbibitions & diffusion?

What is the role of osmotic potential in regulating water potential of plant
cells.

What are the factors affecting the rate of diffusion.

Mention two conditions necessary for imbibitions to occur?

What is the water potential of pure water?

Define guttation.

What determines the direction of flow of water from one cell to another
cell?

What forces are involved in absorption of water from soil by root hairs.

Describe water potential? What are the factors influencing it?

Explain facilitated diffusion?

Distinguish between transpiration & evaporation?

Why is c4 photosynthetic system more beneficial than c3 photosynthetic
system?

State the significance of plasmolysis?

Why is salt added in excess to pickles?

Define plasmodesmata?

Name two factors that affect water potential?

Describe the cohesive force theory of ascent of sap in plants?

Explain why pure water has maximum water potential?

Explain pressure flow hypothesis for translocation of sugars in plants?

Give the main purposes of transpiration?

Distinguish between active transport & passive transport

Why cell is called an osmotic system?

When does wilting occur?

Define translocation? [

Name two anti-transpirants?

What causes the opening and closing of guard cells of stomata during transpiration?

Explain pressure flow hypothesis of translocation of sugars in plants.

 Explain why xylem transport is unidirectional and phloem transport bi-directional.

What essential role does the root endodermis play during mineral absorption in plants?

Discuss the factors responsible for ascent of xylem sap in plants.

Describe transpiration pull model of water transport in plants. What are the factors influencing transpiration? How is it useful to plants?

What role does root pressure play in water movement in plants?

What role does root pressure play in water movement in plants?

How is the mycorrhizal association helpful in absorption of water and minerals in plants?

(a) With the help of well-labelled diagrams, describe the process of plasmolysis in plants, giving appropriate examples. (b) Explain what will happen to a plant cell if it is kept in a solution having higher water potential.

What happens when a pressure greater than the atmospheric pressure is applied to pure water or a solution?

Briefly describe water potential. What are the factors affecting it?

Differentiate between the following: (a) Diffusion and Osmosis

(b) Transpiration and Evaporation

(c) Osmotic Pressure and Osmotic Potential

(d) Imbibition and Diffusion

(e) Apoplast and Symplast pathways of movement of water in plants.

(f) Guttation and Transpiration.

Explain why pure water has the maximum water potential.

Describe the role played by protein pumps during active transport in plants.

What are porins? What role do they play in diffusion?

What are the factors affecting the rate of diffusion?