Frank Brothers Solutions for ICSE Class 10 Biology Chapter 4 Absorption By Roots

(i) Osmosis: Osmosis is the movement of solvent molecules from a region of higher concentration to a region of lower concentration through a semi-permeable membrane. This is like when water moves through a tea bag to make tea. (ii) Diffusion: It is the movement of molecules or ions from a region of higher concentration to a region of lower concentration to equalize the concentration of the two regions. (iii) Turgor Pressure: It is the actual hydrostatic pressure developed inside a cell as a result of entry of water into it. (iv) Hypertonic solution: A solution whose concentration is more than that of cell sap is called hypertonic solution. (v) Plasmolysis: The shrinkage of cytoplasm of a living cell as a result of exosmosis is known as plasmolysis.

Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration. This happens when you spray perfume in a room and everyone can smell it after some time. Osmosis is the movement of water molecules through a semi-permeable membrane from a region of lower solute concentration to a region of higher solute concentration. Both processes help substances move in living things without using energy.

Endosmosis is the movement of water into a cell when the cell is placed in a hypotonic solution, causing the cell to swell. Think of a raisin becoming plump when soaked in water. Exosmosis is the movement of water out of a cell when the cell is placed in a hypertonic solution, causing the cell to shrink.

The pressure of water developed inside the roots due to active absorption of water when transpiration is very low and the rate of absorption is high is known as root pressure. This is like when you drink water through a straw and create pressure inside it. You can actually see this pressure working when water drops come out of leaf tips early in the morning.

Permeability is the property of a membrane to allow the passage of both solute and solvent molecules. Think of it like a cloth filter that lets both tea leaves and water pass through it. This means everything can move freely across the membrane.

Root hairs absorb maximum water because in this region, the xylem is not fully mature but the epidermis and endodermis are still permeable to water. Think of root hairs as tiny straws that can easily soak up water from soil. This makes them perfect for quick water absorption.

Roots help in the absorption of water. Just like how a straw sucks up water from a glass, roots suck up water from soil. They also help in the absorption of minerals.

(i) Difference between Filtration and Diffusion (ii) Difference between Turgor Pressure and Osmotic Pressure (iii) Difference between Hypotonic and Hypertonic Solution. Think of a raisin becoming plump when soaked in water - that's hypotonic solution at work! (iv) Difference between Osmosis and Diffusion (v) Difference between Flaccid condition and Turgid condition (vi) Difference between Plasmolysis and Deplasmolysis

Plasmolysis helps in the preservation of meat and fish by salting. It is also helpful in the preservation of jellies and jams by adding concentrated sugar solution to them. This is why your grandmother adds lots of sugar when making mango pickle at home. It helps in plasmolysing the spores of bacteria and fungi.

Turgor pressure keeps the soft organs like flowers, young shoots, leaves, etc. in stretched form. Think of how a balloon stays round when filled with air. It is also essential for the growth of the cells. Changes in the turgor pressure causes opening and closing of stomata.

The epidermis and endodermis of root hairs are permeable to water. Think of them like tiny doors that let water pass through easily. Root hairs have a very large surface area.

(i) The main root with its many branches form a network in the soil. The root hairs get entangled in the soil particles and remain in close contact with the capillary water surrounding the soil particles. The epidermal cells of root hairs have vacuoles which contain cell sap. Generally, the cell sap is more concentrated than the soil solution. Think of it like a sponge soaking up water from wet soil. As a result the water enters inside the root hair cells by endosmosis. This water dilutes the epidermal cell sap solution. Then water enters into the cortical cells by osmosis and reaches the endodermal cells and then pericycle cells. From this layer water then enters in the xylem tissue. In this way, the water is absorbed and translocated up to xylem of In this way, the water is absorbed and translocated up to xylem of the root by osmosis. (ii) (a) Cell wall separates the two solutions - cell sap and soil solution and is permeable which means it allows the water to enter inside the root hair cells by endosmosis.(b) The cytoplasm contains vacuoles having cell sap or solution of mineral salts. This cell sap being more concentrated than the soil solution help in water absorption by endosmosis. (iii) If the soil was watered with extremely concentrated solution of sodium chloride, the water will move out from the root hair due to osmosis and thus, plasmolysis will take place.

(i) Osmosis(ii) Root hair(iii) Sugar solution. This is similar to how raisins swell up when kept in water - water moves from outside into the raisin through its skin.(iv) The level of the liquid in the capillary tube rises.

(i) Osmotic pressure(ii) Isotonic solutions(iii) Cohesive force(iv) Active absorption(v) Xylem. This is like tiny pipes in plants that carry water from roots to leaves. (vi) Plasmolysis(vii) Endosmosis(viii) Endosmosis(ix) Diffusion

Cell wall: It is freely permeable which surround the cell membrane of the cell. Cell membrane: It is semi-permeable that allows only water to pass through it and surround cytoplasm of the cell. Think of it like a security guard at a building who only lets certain people enter. Vacuole: It contains cell sap. The concentration of cell sap is more than the soil water. So, endosmosis takes place. Cytoplasm: It is the fluid which fills up the cell and contains all the cell organelle. Nucleus: A nucleus is a membrane-bound organelle that contains the cell's chromosomes. Pores in the nuclear membrane allow for the passage of molecules in and out of the nucleus.

Xylem is the tissue that carries water from roots to leaves, just like how pipes carry water to different floors of a building.

Plasmolysis. This happens when plant cells lose water and shrink away from their cell walls, just like how a grape becomes a raisin when it dries out.

The root hairs become flaccid when fertilizers are added to the moist soil around them because fertilizers with moist soil become hypertonic which causes plasmolysis in the cells of the root hair. This is like when you put too much salt in pickle water - it draws out water from vegetables. The turgidity is lost and the cell becomes flaccid.

Diffusion is the process by which molecules distribute themselves evenly within the space they occupy. When you spray perfume in one corner of a room, it slowly spreads everywhere. This happens because molecules are always moving and spreading out from areas where there are many molecules to areas where there are fewer molecules.

Endosmosis is the term for the inward movement of solvent molecules through the plasma membrane of a cell. This happens when water moves into a cell because there is more salt or sugar inside the cell than outside. It's like water flowing into a sponge when you dip it in a bowl.

(i) The cell shown in the diagram is in a plasmolysed state. (ii) The cell membrane acts as a selectively permeable membrane. (iii) If the cell had been placed in distilled water instead of strong sugar solution, plasmolysis would not have occurred. Think of it like a raisin - when you put a grape in sugar water, it shrinks and becomes wrinkled like a raisin. (iv) If the cell possessed chloroplasts, they would be present in the protoplasm/cytoplasm. (v) One feature of this plant cell which is not present in animal cells is the cell wall.

1. Plasmolysed cell 2. Plasma membrane 3. Large vacuole. When you put salt on a cut cucumber, it becomes soft because water leaves the cells just like in plasmolysis. This happens when plant cells lose water and shrink. 4. The chloroplasts would be present in the shrunken protoplast. 5. Cell wall

The raisins swell up when placed in water because the water is hypotonic as compared to the raisins so the water enters inside the raisins as a result of endosmosis. Saline water is hypertonic. So any infectious agent such as bacteria in the throat gets plasmolysed and this cures the infection. This is why doctors tell us to gargle with salt water when we have a sore throat. Jam, jellies and pickles are kept in hypertonic solution of sugar or salt in which plasmolysis of bacteria and fungi takes place. This kills the bacteria and fungi and hence, pickles, jam and jellies are preserved properly. The leaves of the wilted lettuce become crisp when kept in cold water because they take up water due to endosmosis in hypotonic solution.

Ascent of sap is the movement of water from the roots to the upper part of the plant. Think of it like drinking juice through a straw - the plant pulls water up through tiny tubes called xylem vessels.

Plants die when salt is sprinkled over them due to plasmolysis of cells. This is like when you put salt on cucumber slices and they become soft and watery. The salt makes the solution hypertonic inside the plant cells which lead to shrinkage of cells or exosmosis.

Root Pressure is the pressure exerted on the liquid contents of the cortical cells of the root, under fully turgid condition, forcing a quantity of water into the xylem vessels and through them upwards into the stem up to a certain height. This is like how a pump pushes water up through pipes in your building. Demonstration of Root pressure: Take a well matured healthy herbaceous plant. The stem of the plant is cut a few centimeters above the base with a sharp knife and attached to a manometer through a rubber tube. After a few hours, the level of mercury rises in the manometer. This is due to the pressure created by water exuded from the cut end of the plant on account of root pressure generated due to entry of water in the root cells.

Water is one of the raw materials for photosynthesis. Water is important for seed germination. Just like how we need water to stay alive, plants also drink water through their roots. Water controls the opening and closing of stomata.

Plants begin to die when concentrated solution of a fertilizer is given to potted plants because fertilizer along with soil water act as a hypertonic solution. This is like adding too much salt to water - it becomes very strong. When this happens, water moves out of the plant roots instead of going in, resulting in exosmosis.

(i) Plants absorb water by their roots.(ii) Roots supply water to the stem and leaves of the plant.(iii) In root hairs, the xylem is not fully mature and the endodermis and epidermis are permeable to water. Think of xylem as tiny water pipes carrying water up from roots to leaves. The phloem works like food delivery tubes carrying sugar made in leaves down to roots.(iv) Water is absorbed by the plants through xylem in all directions.(v) The food on the other hand is transported with the help of phloem.

(i) The aim of the experiment is to show that conduction of water in plants takes place through xylem.(ii) In shoot, (a) phloem has been removed. In shoot (b), xylem has been removed. Think of xylem like drinking straws that carry water up from roots to leaves. When these water pipes are cut, plants cannot get water.(iii) In shoot (b), xylem has been removed so the leaves are wilted. But in shoot (a), xylem has not been removed so the leaves are turgid.

(i) In (c), the water would move up the fastest.(ii) In (b), the water would move up slowly. This is like how a plant wilts when you remove its leaves because it cannot pull water up properly. The oil layer works just like putting plastic wrap over a glass of water.(iii) To prevent evaporation of water.(iv) Absorption of water by the roots.