If solute concentration is high and water potential is low in the root cells, water can enter from soil to root cells through. However, the absorptive process does not occur during direct injection of drug by intravenous or intra arterial injection. This type of absorption which is non- osmotic and against the osmotic gradient requires the expenditure of metabolic energy probably through respiration. From the capillaries, the fat-soluble substances pass into the lymph. The main criterion for the difference between active and passive diffusion is energy consumption. This may be a two way process. If solute concentration is high and water potential is low in the root cells, water can enter from soil to root cells through.
They are first acted upon by the bile salts and phospholipids to form small, spherical droplets called micelles that are water-soluble molecules and then absorbed. According to this theory, the root cells behave as an ideal osmotic pressure system through which water moves up from the soil solution to the root along an increasing gradient of D. Summary — Active vs Passive Diffusion Active and passive diffusion are two methods that facilitate the movements of molecules. Water from endodermal cells is drawn into the cells of pericycle by osmotic diffusion which now becomes turgid and their suction pressure is decreased. Active transport is the carrier mediated transport. Movement of ions occurs against the concentration gradient. But, passive diffusion does not require energy.
This energy is used to transport nutrient molecules across the membrane. Quinidine and pyrimethamine are antimalarials and basic, so are ionized in stomach and unionized in intestines, from where they are absorbed. In active transport, particles like proteins, large cells, ions and sugar are transported. Therefore, if we want to have slower time of absorption, we can make the particle size larger. It also occurs by subcutaneous, intra muscular and transdermal.
This is probably because at low temp: i The viscosity of water and protoplasm is increased, ii Permeability of cell membranes is decreased, iii Metabolic activities of root cells are decreased, and iv Growth and elongation of roots are checked. Water is absorbed as a result of tension created by transpiration pull in passive absorption. It goes from high concentration to lower concentration, to maintain equilibrium. Active transport is in an opposite direction to that of diffusion. Active Membrane Transport: Active membrane transport is for the which cannot cross the lipid membrane and require transport proteins. Therefore, they need special support for transportation.
Thus the absorption is greater in the small intestine due to the large surface area. A membrane pump operates across the cell membranes which transports the nutrients from the lumen of the intestine into the cells. In here, the net movement of molecules occurs from a high concentration to a low concentration due to the kinetic energy. Water is absorbed from soil and eventually reaches the leaves after being distributed to all parts of the plants. Sandy soils are, therefore, not good for water absorption. In passive absorption of water, the process is totally different; when plant losses water due to transpiration, it develops a water deficit nd draws water from petiole, petiole from stem nd stem from root.
Due to its larger surface area, thin wall lining the cavity and large number of finger-like projections, called the villi, maximum absorption takes place in this portion of the alimentary canal. In short we can say that acidic drugs are better absorbed in the acidic medium while basic drugs are better absorbed in the basic medium. Nutrients like sodium ions, glucose, galactose and amino acids are transported actively. In active absorption of water, water enters into the root hairs by process of osmosis. Energy Expenditure: No energy is required for this type of transport. Usually the plants absorb capillary water i.
There is no direct evidence, but some scientists suggest involvement of energy from respiration. As a result, the concentration of ions osmotica in the xylem vessels is more in comparison to the soil water. It differs from passive diffusion since it occurs against the concentration gradient and the need for energy. Hence, it does not require cellular energy. This water id conducted and then distributed to the whole plant, eventually reaching the leaves. This gradient of water potential causes endosmosis.
But according to Kramer 1969 the active absorption of water is of negligible importance in the water economy of most or perhaps all plants. Thus the different plants if grown in the same soil wilt at different times depending upon their osmotic potential after the water supply to the soil is stopped. Active Membrane Transport: Active membrane transport is for the which cannot cross the lipid membrane and require transport proteins. Active transport mechanism is saturable and can be inhibited by competing drugs. However, bulk flow is dependent on the blood flow, more the blood flow, more rapid is the absorption. Available Soil Water: Sufficient amount of water should be present in the soil in such form which can easily be absorbed by the plants. Waste is diffused out and excreted and nutrients are diffused into the cells.
This type of transport is also specific and saturable. Apart from being the largest Class 11 community, EduRev has the largest solved Question bank for Class 11. These substances are then transported throughout the body by the lymphatic system, which drains them into the blood near the heart. This process requires cellular energy. The undigested food then passes into the large intestine where it is temporarily stored.
This type of transport is utilized by large molecular weight drugs. Thus, it is the key difference between active and passive diffusion. Depending upon their diameters the soil particles are classified as below: Gravel………………………………………………………………………………………………. Field Capacity or Water Holding Capacity of the Soil : After heavy rainfall or irrigation of the soil, some water is drained off along the slopes while the rest percolates down in the soil. The entry of solute particles nutrients increases the osmotic pressure. That is; the transport proteins embedded in the cell membrane are modified to do this activity. Yet the membrane is also a formidable barrier, allowing some dissolved substances, or solutes, to pass while blocking others.