NCERT solutions for class 11 biology chapter 11 transport in plants: This chapter will tell you, how water reaches the top of tall trees, why and how different substances move from one cell to the other, whether all substances move in a similar way or in the same direction or whether metabolic energy is required for moving substances. In NCERT solutions for class 11 biology chapter 11 transport in plants, you will get questions along with their answers and all will be related to the transport in the plants and there you will get to know how water reaches the top of the plant. In this chapter you will learn that plants need to move molecules over very long distances, as compared to the animals; they also do not have a circulatory system inside them. Solutions for NCERT class 11 biology chapter 11 transport in plants contain solutions to all those questions which are mentioned in this chapter. CBSE NCERT Solutions for Class 11 Biology Chapter 11 Transport in Plants will help you to understand some of the transport processes in plants. If you are looking for an answer from any other chapter even from any other class then go with NCERT Solutions, there you will get all the answers of NCERT easily.
Here the important topics of CBSE NCERT solutions for class 11 biology chapter 11 transport in plants are mentioned below:
11.1 Means of Transport
11.1.2 Facilitated Diffusion
11.1.3 Active Transport
11.1.4 Comparison of Different Transport Processes
11.2 Plant-Water Relations
11.2.1 Water Potential
11.3 Long Distance Transport of Water
11.3.1 How do Plants Absorb Water?
11.3.2 Water Movement up a Plant
188.8.131.52 Root Pressure
184.108.40.206 Transpiration pull
11.4.1 Transpiration and Photosynthesis – a Compromise
11.5 Uptake and Transport of Mineral Nutrients
11.5.1 Uptake of Mineral Ions
11.5.2 Translocation of Mineral Ions
11.6 Phloem Transport: Flow from Source to Sink
11.6.1 The Pressure Flow or Mass Flow Hypothesis
In NCERT Chapter 11 - Transport in Plants of NCERT you will study that in higher plants, there is a vascular system comprising of xylem and phloem, responsible for translocation. Water minerals and food cannot be moved within the body of a plant by diffusion alone. They are, therefore, transported by a mass flow system - the movement of substance in bulk from one point to another as a result of pressure differences between the two points. To understand the solutions for NCERT class 11 biology chapter 11 transport in plants, you should go through all the topics of this chapter carefully.
After going through NCERT solutions for class 11 biology chapter 11 transport in plants line by line, you must be able to understand all the answer the questions which are given below:
CBSE NCERT Solutions for Class 11 Biology Chapter 11 Transport in Plants- Solved Exercise Questions-
Q1. What are the factors affecting the rate of diffusion?
The factors affecting the rate of diffusion are as follows
1. The density of the substance- The rate of diffusion of a substance is directly proportional to the square root of its relative density
2. Permeability of the medium- Rate of diffusion decreases with the permeability of the medium
3. Temperature- A rise in temperature increases the rate of diffusion
4. Diffusion pressure gradient- Rate of diffusion is directly proportional to the diffusion pressure gradient
Q2. What are porins? What role do they play in diffusion?
Porins are proteinaceous hydrophilic channels present in the outer membrane of plastids, mitochondria and some bacteria. They allow passage of large biomolecules, even small-sized proteins as per diffusion gradient. Aquaporins are water channels for the diffusion of water molecules across the plasma membrane.
NCERT solutions for class 11 biology chapter 11 transport in plants:
Q3. Describe the role played by protein pumps during active transport in plants.
Protein pumps are carrier proteins which take part in the transport of solutes across the cell membrane with the help of energy in the form of ATP even against a concentration gradient. On being activated with energy, the protein pump picks up solute particles from outside and transport them to the inner side into the cytoplasm. There are a number of protein pumps such as Na- K pump, Ca pump
Q4. Explain why pure water has the maximum water potential.
Water potential is the quantitative measure of the tendency of water to move from one part to the other during various cellular processes. It is denoted by the Greek letter Psi or V. The water potential of pure water is always taken as zero at standard temperature and pressure. It can be explained in terms of the kinetic energy possessed by water molecules. When water is in the liquid form, the movement of its molecules is rapid and constant. Pure water has the highest concentration of water molecules. Therefore, it has the highest water potential. When some solute is dissolved in water, the water potential of pure water decreases.
Q5. Differentiate between the following:
(a) Diffusion and Osmosis
|It refers to the passive movement of particles, ions and molecules along the concentration gradient
||The process of movement of a solvent across a semipermeable membrane
|It does not require a semi-permeable membrane
||It requires a semi-permeable membrane
Solutions for NCERT class 11 biology chapter 11 transport in plants:
Q5. Differentiate between the following:
(b) Transpiration and Evaporation
|Transpiration is a physiological process
||Evaporation is a physical process
|It occurs through stomatal pores
||It occurs through any surface of the plant
|It is controlled by environmental as well as physiological factors
||It is controlled by environmental factors only
Q5. Differentiate between the following:
(d) Imbibition and Diffusion
Imbibition is a special type of diffusion when water is absorbed by solid colloids causing them to increase in volume. For example absorption of water by seeds and dry woods
|Diffusion refers to the movement of solute molecules along a concentration gradient
Q5. Differentiate between the following:
(e) Apoplast and Symplast pathways of movement of water in plants.
It consists of nonliving parts of plants body such as cell wall and intercellular spaces.
It consists of living parts of the plant body such as protoplast connected to plasmodesmata.
There is little resistance in the movement of water
Some resistance occurs in the movement of water.
The metabolic state of root does not affect the apoplast pathway.
The metabolic state of root directly affects the symplast pathway.
Water potential is the quantitative measure of water to move from one part of the plant to the other part during various cellular processes such as diffusion, osmosis, etc. It is denoted by the Greek letter Psi or and is expressed in Pascals (Pa). Water pressure of pure water is taken as zero at standard temperature and pressure. A solution has less water potential due to less water concentration. Water potential of a cell is affected by solute and pressure potential.
Solute potential- The magnitude of lowering of water potential due to the dissolution of solute is called solute potential.
Pressure potential- The water potential of pure water or a solution increases on the application of pressure values more than atmospheric pressure. It is termed as pressure potential.
The relation between water potential and pressure potential is as follows:
Q8. (a) With the help of well-labelled diagrams, describe the process of plasmolysis in plants, giving appropriate examples.
Plasmolysis refers to the shrinkage of the cytoplasm of the cell away from its cell wall under the influence of a hypertonic solution. Plasmolysis occurs because of the movement of water from the intracellular space to the outer-cellular space. This happens when the Plant cell is Placed in a hypertonic solution (i.e., a solution having more solute concentration than the cell cytoplasm). It will cause the water to move out of the cell and toward the solution. The cytoplasm of the cell Shrinks and the cell is said to be plasmolysed. This process can be observed in an onion peel kept in a highly concentrated salt solution.
CBSE NCERT solutions for class 11 biology chapter 11 transport in plants:
Q9. How is the mycorrhizal association helpful in absorption of water and minerals in plants?
Mycorrhiza refers to the symbiotic association of fungi with the root systems of higher plants. The hyphae of fungi form a dense network around the young roots and they can even penetrate the cells of the roots. The mycorrhizal hyphae help the plants in getting nutrients especially phosphorous. Due, to this reason, the mycorrhizal association is obligated in some plants. For example, Pinus seeds don't germinate and establish in the absence of mycorrhizal associations.
Q10. What role does root pressure play in water movement in plants?
Root pressure is a positive pressure that develops in the xylem sap of the root of plants. Root pressure is the manifestation of active water absoorptionsThe root pressure theory was given by Priestley in 1916 to establish the role of root pressure in the movement of water. The roles played by root pressure in the water movement of plants are as follows:
1. Root pressure is able to transport water up to small heights.
2. Root pressure helps in re-establishing the continuous chains of water molecules in the xylem.
Q11. Describe transpiration pull model of water transport in plants. What are the factors influencing transpiration? How is it useful to plants?
Transpiration pull model of water transport in plants
Transpiration is the loss of water in the form of water vapour from aerial parts of plants. In tall trees, the water rises with the help of the transpirational pull generated by transpiration. This is called the cohesion-tension model of water transport. According to this model, the water is mostly pulled from roots to leaves due to the driving force of transpiration from the leaves. The water molecules remain attached with one another by cohesion force. The water molecule does not break in vessels and tracheid due to adhesive force between their walls and water molecules. On account of tension created by transpiration, the water column of a plant is pulled up passively from roots to great heights.
Factors influencing transpiration
The external factors affecting transpiration are wind, speed, light, humidity, and temperature. The physiological factors affecting transpiration are canopy structure, number and distribution of stomata, water status of plants, and the number of open stomata etc. The advantages of transpiration are as follows:
1. It creates a transpirational pull for absorption and transport in plants.
2. It supplies water for photosynthesis.
3. It cools the leaves and maintains their shape and size.
Q12. Discuss the factors responsible for ascent of xylem sap in plants.
The various factors responsible for the ascent of sap are as follows:
1. Capillarity- It is the limited rise of water in narrow tubes or capillaries due to forces of cohesion amongst the molecules of water and their property of adhesion to other substances.
2. Imbibition- It is the ability of hydrophilic colloid to attract and hold water on the surface and inside their interspaces.
3. Root pressure- It is the positive pressure that pushes sap from below due to active absorption by roots.
4. Transpiration pull- Transpiration in aerial parts brings the xylem sap under negative pressure or tension due to the continuous withdrawal of water by them. Water column does not break due to its high tensile strength related to high force of cohesion and adhesion.
Q14. Explain why xylem transport is unidirectional and phloem transport bi-directional.
Leaves are the site of food production for plants as they carry out photosynthesis. The major function of phloem is to conduct the food from the source to the sink. Since, here the source is single and sink can be multiple i.e. roots, branches, flower etc. so the conduction of food takes place in multiple directions. During spring also, the process of food conduction reverses and the food stored in the sink is mobilised toward the growing buds of the plant, through the phloem. Since the foof is being conducted to many directions. the movement of food in the phloem is called bidirectional (i.e., upward and downward). The transport of water, on the other hand, takes place only from the roots to the leaves. Therefore, the movement of water and nutrients in the xylem is unidirectional.
Q15. Explain pressure flow hypothesis of translocation of sugars in plants.
Pressure flow hypothesis is the most accepted theory for the translocation of sugar from source to sink. Glucose is prepared at the source by photosynthesis which is converted into disaccharides sucrose which further moves into companion cells and then into sieve tube cells by active transport. Loading of phloem at source creates a water potential gradient that facilitates the mass movement in the phloem. Sieve tube cells of phloem form a long column with holes in their wall called sieve plates. Cytoplasmic strands pass through the hole in the sieve plates to form a continuous filament. Hydrostatic pressure developed in sieve tube cells moves the sap in the phloem. At the sink, incoming sugar is actively moved out of the phloem as complex carbohydrates. The loss of solute produces a high water potential in the phloem and water passes out and returning into the xylem.
Q16. What causes the opening and closing of guard cells of stomata during transpiration?
Stomata are the tiny pores present on the surfaces of leaves that help in the exchange of gases. A stoma consists of bean-shaped (in dicot) or dumbbell-shaped (in monocots) guard cells that are surrounded by the modified epidermal cells called subsidiary cells. The opening and closing of the stomata are mainly due to change in the turgidity of guard cells. The inner walls of the guard cells are thick and elastic, while the outer walls are thin. Numerous microfibrils are present in the cell walls of guard cells to facilitate the opening and closing of the stomata.
Stomatal opening- At the time of the opening of the stomata, the turgidity of the guard cells increases. As a result, the outer walls bulge and the inner walls become crescent-shaped. The stomatal opening is facilitated by the radial arrangement of the microfibrils.
Stomatal closing- At the time of the closing of the stomata, the guard cells lose their turgidity, the outer and inner walls retain their original shapes, and the microfibrils get arranged longitudinally.
If you have any query in understanding these solutions which are mentioned in the above then again go through the chapter of the NCERT textbook, then try to solve them by yourself and compare them with NCERT solutions for class 11 biology chapter 11 transport in plants. This will help you not only for your school exam as it will also help you in the preparation of other competitive exams like NEET.
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