Excretion In Plants And Animals Pdf

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Respiration is the process of releasing energy from food. Like human beings and other animals, plants also need oxygen from the environment and release carbon dioxide.

Excretion The elimination of the waste products of metabolism from an organism. Secretion The passage of useful intracellular molecules into the extra-cellular environment. This term should not be confused with excretion, which deals with waste substances. Egestion The elimination of waste substances mainly undigested food , which have never been involved in cellular metabolic activities.

Excretion and Osmoregulation

Excretion is a process in which metabolic waste is eliminated from an organism. In vertebrates this is primarily carried out by the lungs , kidneys , and skin. Excretion is an essential process in all forms of life. For example, in mammals, urine is expelled through the urethra , which is part of the excretory system. In unicellular organisms , waste products are discharged directly through the surface of the cell. During life activities such as cellular respiration, several chemical reactions take place in the body. These are known as metabolism.

Excretion , the process by which animals rid themselves of waste products and of the nitrogenous by-products of metabolism. Through excretion organisms control osmotic pressure—the balance between inorganic ions and water—and maintain acid-base balance. Every organism, from the smallest protist to the largest mammal, must rid itself of the potentially harmful by-products of its own vital activities. This process in living things is called elimination, which may be considered to encompass all of the various mechanisms and processes by which life forms dispose of or throw off waste products, toxic substances, and dead portions of the organism. The nature of the process and of the specialized structures developed for waste disposal vary greatly with the size and complexity of the organism. Four terms are commonly associated with waste-disposal processes and are often used interchangeably, though not always correctly: excretion, secretion , egestion, and elimination.

Chemical reactions occur in the cells of living organisms all the time to carry out the life processes. The sum of these reactions is called metabolism. Metabolism produces useful products as well as toxic poisonous by-products. These toxic substances have to be removed as they are harmful if allowed to accumulate. The removal of metabolic waste products from the body of an organism is known as excretion. The major excretory products are carbon dioxide, excess water, and nitrogenous compounds like ammonia, urea, uric acid, etc.

Excretion and Osmoregulation

Plants are not generally considered to possess special mechanisms of elimination. Photosynthetic activities of green plants, in the presence of light, produce oxygen , which diffuses out through openings in the leaves stomata or through the cell walls of roots and other plant structures. Excess water passes to the exterior via similar routes and is eliminated by processes of guttation droplet exudation and transpiration evaporation of water from plant surfaces. Green plants in darkness or plants that do not contain chlorophyll produce carbon dioxide and water as respiratory waste products. Carbon dioxide is secreted in the same manner as oxygen via diffusion through stomata and cell walls.

Respiration is the process of releasing energy from food. Like human beings and other animals, plants also need oxygen from the environment and release carbon dioxide. This shows that even plants undergo the process of respiration. So, Oxygen and carbon dioxide are also called respiratory gases. Diffusion is the only process through which much needed oxygen is supplied to all the cells of the plants. Diffusion occurs in roots, stems and leaves.

Respiration and Excretion in plants

Not a MyNAP member yet? Register for a free account to start saving and receiving special member only perks. The process-based, mass balance approach would begin by predicting nitrogen, carbon, and sulfur in manure excreted. This prediction would be made by subtracting the quantities of these elements in animal products from the quantities consumed. For every major type of farm animal and every production group within these types, such predictions of intake are already available.

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T he excretory system consists of several organs and structures that may have diferent features depending on the animal species. Its main function is to eliminate by filtration waste products resulting from cellular metabolism or incorporated from the environment, for example, during feeding, salt excess in seabirds, etcetera. The main excretory system in animals is the urinary system. T he urinary system is composed of the kidneys, in which urine is produced, ureters, urinary bladder, and the urethra. An initial filtration of the blood is produced in the kidneys.

There are diverse physiological functions of nitrogen end products in different animal groups, including excretion, acid-base regulation, osmoregulation and buoyancy. Animals excrete a variety of nitrogen waste products, but ammonia, urea and uric acid predominate. A major factor in determining the mode of nitrogen excretion is the availability of water in the environment. Generally, aquatic animals excrete mostly ammonia, whereas terrestrial animals excrete either urea or uric acid.


The parts involved in excretion form the excretory system. Excretory system in humans. The waste which is present in the blood has to be removed from the body.


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Chemical reactions occur in the cells of living organisms all the time to carry out the life processes. The sum of these reactions is called metabolism. Metabolism produces useful products as well as toxic poisonous by-products.

Diverse mechanisms have evolved that enable the various animal species to inhabit a wide range of environments.

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