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Transport in Plants Class 11 Introduction –
Transport in Plants Class 11:- In this chapter,we are going to study how water reaches to the top of tall plants.Plants needs to move molecules over very long distances,more than the animals do.They do not have a circulatory system.Photosynthates or food synthesised by leaves have to move to all the parts including the root tips inside the soil. In this chapter,we are going to study the transportation process in case of plants.
Transportation over small distances occurs by diffusion and by cytoplasmic streaming,and over long distances it occurs through the vascular system,the Xylem and the phloem. This process is termed as translocation.
In rooted plants, transport in Xylem is unidirectional,from roots ti stems. And in case of organic and mineral nutrients,it is multidirectional.
Let us study this in more details.
Biology Chapter 11 Transport in Plants Class 11 Important Questions and Answers
*Plants move molecules to long distances, much more than the animals without possessing any circulatory system. The water that is absorbed by roots has to reach every part of the plant. The process of photosynthesis in plants by leaves is necessitated to move across all parts even the tips of the roots that are buried deep in the soil. Substances that are transported in flowering plants are water,mineral nutrients, organic nutrients, and plant growth, regulators i.e. PGR’s. Through cytoplasmic streaming supplemented by active transport and diffusion, substances can move over the short distances. However, over longer distances, transportation is carried out by vascular system – the Xylem and the Phloem. This is referred to translocation. Continue reading to get more information of transportation in plants.
Transport in Plants Class 11 – Very Short Answer Type Questions-
Q.1. Addition of urea to the flowering plants so as to grow faster in the earthen pot results in death of the plant after a while. What can be the cause of this?
A.1. Due to exosmosis, plant dies. Water gradually tends to move out of plant cell as the solution outside is a hypertonic solution whereas the plant cell is in hypotonic solution. This causes plasmolysis of the cells of the roots and ultimately, leads to the death of the plant.
Q.2. The direction and rate of Osmosis depends upon the ________
A.2. It depends upon both pressure gradient and the concentration gradient.
Q.3. Water absorption by dry seeds from the soil rises the ______, hence aiding seedlings to appear out of soil.
A.3. The seed materials imbibe water which propels the seedlings out of soil hence the seed swells and imbibition pressure rises within the seeds enabling- seeds germination.
Q.4. What do u mean by solute potential and water potential?
A.4. The potential energy of water is considered to be the water potential. It is also regarded as a measure of the difference between potential energy of pure water and of a given sample of water. The magnitude of water potential lowers because of the dissolution of solute,it is known as the solute potential.
Q.5. Explain water moves into the roots?
A.5. The apoplast pathway causes water to flow in the root, as the cortical cells are generally loosely arranged which provide no resistance to water that moves through the mass flow. It occurs due to the cohesive and adhesive properties exhibited by the water. Symplast pathway is also attributed to the movement of the molecules of water within the root.
Q.6. Which is the molecular movement that is highly selective requiring special membrane proteins without needing any energy?
A.6. Facilitated diffusion is the molecular movement that is highly selective .
Q.7. Define transportation in Plants?
A.7.The process of distribution, transfer or the movement of water, minerals and food materials to all parts of plant body is called Transportation in Plants.
Q.8.How transportation process takes place in plants?
A.8.Transportation in plants occurs at three levels:
- Individual cells are involved in the uptaking and releasing of water molecules and other solutes particles.
- Short distance transportation of substances from one cell to the another cell.
- Xylem and the phloem are the two tissues responsible for movement of water molecules and other solutes particles.
Q.9. Define Translocation?
A.9. Movement of water molecules and other nutrients from the soil to all other parts of the plant is known as Translocation.
Q.10.Name different means of Transportation in plants?
A.10.Three different means of Transportation in plants are there :
- Active transport.
- Facilitated diffusion.
Q.11.What is Plasmolysis and osmosis.
Plasmolysis is the process of contraction of the protoplasm of cells within the plants due to the loss of water through osmosis.
Osmosis is the process of movement of the molecules from a solution of low concentration to a solution of high concentration through a semi-permeable membrane of a cell.
Transport in Plants Class 11 – Short Answer Type Questions
Q.1. How the analysis of the exudate enable one to find out the minerals and the form in which they are assembled in plant?
A.1. The chemical analysis of the exudate(plant sap) can help us understand the form and identity the mineral nutrients that are transported in the plants as the exudate is a mixture of organic and inorganic compounds such as ions, amino acids(AA), sugars, etc.
Example- Sulphur in sulphate ion forms, nitrogen is absorbed and transported as NO2 and NO3.
Q.2 The method that can be used to increase the life span of cut plants in a vase is?
A.2. By quickly transferring them into water, its lifespan can be increased as air will immediately shift into the tissues that conducts water and fill the cell. In addition, supplying the elements and the nutrients in varying concentrations can increase its life span.
Example – Cytokine, is a hormone that is sprayed or can be dipped in its solution to delay plant senescence.
Q.3. The rate of transpiration in different species of plant that is cultivated in the same area differ in a particular time? Explain.
A.3. Rate of transpiration is governed by several factors. If two species have the same morphology and are related to each other, then the rate of transpiration depends on external factors such as humidity, temperature, wind velocity, and light intensity, etc.
Q.4. Why the intracellular levels of K+ in animal cells is higher than extracellular levels?
A.4. Ion channels may be closed or open, i.e, they are ‘gated’. The Na+, K+, ATPase generate an imbalance in charges across the plasma membrane by passing 3Na+ out of the cell for each 2K+ ion carried within the cell causing the inside negative relative to the outside. Then the membrane is referred to as polarized. Hence intracellular levels of K+ are higher in the cell.
Transport in Plants Class 11 Quiz
Q.5. Why do cut pieces of the beet root gives colour in the hot water and not in the cold?
A.5. It is because the beet root pigment dissolves and disperses immediately in the hot water as hot temperature facilitates leakage of the plasma membrane and discharge of beetroot pigment. It is not the same in case of cold water.
Transport in Plants Class 11 – Long Answer Type Questions
Q.1. Does plants require to adjust the solute types that reach at the xylem? Name the molecules that helps in adjusting. How does the regulation of the type and the quantity of solutes that reach the xylem brought about by plants?
A.1. Yes, adjustment is required. The end dermal cells have the transport proteins that aid in regulating and adjusting the movement of the solute. Since, soil minerals are present as the charged particles with less concentration in comparison to roots, they all can’t be transported passively across the cell membranes of the root hairs. Hence through passive and active processes,minerals are transported to the xylem.
On reaching at xylem, they are further transported towards the sink through the transpiration stream. Mineral ions at sink region are unloaded through active uptake by receptor cells and diffusion. Few mineral ions that move through the xylem are:
- Nitrogen moves in plants as inorganic ions- NO2 and NO3 but much of the nitrogen moves in the form of amino acids,AA and related to the organic compounds.
- Minerals ions are frequently remobilized specifically from the older senescing parts. Leaves that are old and dying export most of its mineral content to the younger leaves. Likewise, before leaves fals offl in deciduous plants, minerals are eliminated from the other parts. Few elements that are readily mobilized are sulphur, phosphorous, potassium and nitrogen.
Q.2. Write differences between the permanent and the temporary wilting.
A.2. Wilting is a process of loss of turgidity of the leaves and other soft aerial parts of a plant that causes folding, dropping and rolling of the non-woody plants. It usually takes place, when rate of water loss is higher than rate at which it is being absorbed.
|Temporary Wilting||Permanent Wilting|
|*Loss of turgidity causes temporary drooping of leaves which is observed during noontime. It occurs when the rate of transpiration exceeds water absorption due to shrinkage of roots. It is recovered from being treated with the water around root hairs in soil. Plants regain their growth.||*Loss of turgidity permanently in the leaves and the other plant parts. The rate of transpiration is higher than rate of absorption but difference is seen below a critical level. Wilting does not recover as the cells do not obtain the turgidity even upon the water addition and environment. The plant dies eventually.|
Q.3. How halophytes able to display a high precell pressure compared to atmospheric pressure?
A.3. Halophytes require soil with a high concentration of salts to grow. In cytoplasm, there is an accumulation of salts due to which the osmotic concentration in the cytoplasm is increased that caused the entrance of water into the cells. Hence, the turgor pressure in halophytes cells is higher in comparison. The two steps are adapted by the halophytes to restrict it:
- In the vacuoles, they collects salts away from cytoplasm.
- Presence of the salt-secreting glands for the elimination of excess salts.
Q.4. Categorise the following into semipermeable membrane (S.P) and the selectively permeable (S.L)
a) Animal Bladder
d) Parchment membrane
e) Egg membrane
A.4. The classification is shown as below:
|Semipermeable Membrane||Selectively Permeable|
|1.Parchment membrane||1.Animal Bladder2.Plasmalemma3.Egg membrane 4.Tonoplast|
Q.5. Write the differences between the process of Guttation and Transpiration in case of plants?
A.5.Transpiration and guttation are the two important processes of the removal of excess water from plants.
The major differences between transpiration and guttation are –
|1. Secretion of water in the form of liquid.||1.Excessive loss of water as the water vapours.|
|2.It occurs through the leaf tips.||2.It takes place within aerial parts of the leaves.|
|3.It occurs during nighttime.||3.It occurs during the daytime.|
|4.It is an uncontrolled natural phenomenon.||4.It is a controlled and a regulated phenomenon.|
|5.The water is abundant in minerals.||5.The water is in pure form.|
Important Questions for Class 11 Biology Chapter 11 Transport in Plants
1) Which is the example of imbibition?
(A) Opening of the stomata.
(B) Uptake of the water by root hair.
(C) Exchange of the gases in stomatal.
(D) Swelling of the seed when put in soil.
(D) Swelling of the seed when put in soil.
A.1. Imbibition is a process in which the water is absorbed by solids-colloids causing them to enormously increase in volume.
Thus the examples of imbibition are:
- Swelling of seed when put in the soil.
- Absorption of water by seeds and dry wood.
2) Match the following –
|1.Leaves||1. Negative Osmotic pressure|
|3.Roots||3. Anti transparent|
|5.Plasmolysed cell||5.Negative osmotic potential.|
3) Ascent of sap be possible without the cohesion and the cohesion of water molecules? Explain the following.
Answer:The ascent of sap is not possible without the cohesion and adhesion of the water molecules.
This is because for root pressure, capillary action and transpiration pull to occur, a force of attraction should exist between the water molecules and between water molecules and walls of plant cell.
4) Explain Uniport, Symport and Antiport. Do they require energy during the process?
Movement of one molecule across a cell membrane (either inside or outside the cell) across the transporter protein is known uniport.
Movement of two different molecules through the cell membrane in same direction is known as antiport.
The coupled transport of two different molecules across a membrane in opposite direction through a protein channel is known as antiport.
No. Uniport, symport and antiport are the types of facilitated diffusion. Hence, they do not requires any kind of energy.
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