Excretion In Animals & Plants - 1 - Class 10

Metabolism of food materials produce some waste materials. Removal of these waste materials from the body is called excretion.

The urinary bladder is the organ that collects urine excreted by the kidneys before disposal by urination. Urine enters the bladder via the ureters and exits via the urethra. 

Malpighian corpuscles are a number of small, round, deep-red bodies in the cortex of the kidney, each communicating with a renal tubule. Malpighian corpuscles average about 0.2 mm in diameter. Each capsule is composed of two parts: a central glomerulus and a glomerular capsule or Bowman's capsule. The corpuscles are part of a filtering system through which nonprotein components of blood plasma enter the tubules for urinary excretion

So, the correct answer is 'Cortex'

The main function of xylem is to transport water from the roots to the shoots and leaves,

Physiologist Walter Cannon coined the term " Homeostasis " In the 1920s, expanding on previous work by late physiologist Claude Bernard. 

Structural and Functional Relationship between Excretory and Digestive Systems in Insects
In most insects, there is no direct structural or functional relationship between the excretory and digestive systems. However, there are exceptions to this generalization.
Cockroach:
- Cockroaches have a specialized structure called the Malpighian tubules, which are part of their excretory system. These tubules are connected to the digestive system.
- The Malpighian tubules function in removing waste products, such as nitrogenous compounds, from the hemolymph (the insect's equivalent of blood).
- The tubules actively transport waste products from the hemolymph into the digestive system, where they are then eliminated with feces.
Earthworm:
- Earthworms are not insects but annelids, but they have a similar excretory system called nephridia.
- Nephridia in earthworms are also connected to the digestive system, allowing waste products to be eliminated through the same opening as the digestive waste.
- This connection between excretory and digestive systems enables efficient elimination of both metabolic waste and undigested food.
Lizards:
- Lizards are reptiles and have different excretory and digestive systems compared to insects.
- In lizards, the excretory system consists of paired kidneys and ureters, while the digestive system includes the stomach and intestines.
- There is no direct structural or functional relationship between the excretory and digestive systems in lizards.
Ants:
- Ants, like most insects, do not have a direct structural or functional relationship between their excretory and digestive systems.
- The excretory system of ants consists of Malpighian tubules, similar to cockroaches, but there is no direct connection to the digestive system.
- Waste products are eliminated through specialized openings called the anus, separate from the digestive system.
Conclusion:
In summary, the only option where there is a structural and functional relationship between the excretory and digestive systems in insects is the cockroach. Cockroaches have specialized structures called Malpighian tubules that are connected to the digestive system, allowing for the elimination of waste products through the digestive system.

Animals accumulate ammonia, urea, uric acid, carbon dioxide, water and ions like Na+, K+, Cl, phosphate, sulphate, etc., either by metabolic activities or by other means like excess ingestion. As metabolism is a characteristic feature of living cells. All the cells produce metabolic wastes. These substances have to be removed totally or partially.

The diameter of the renal afferent vessel is larger as compared to efferent vessel so that more blood may flow in the efferent arteriole thereby increasing the blood pressure in glomerus.

Animals are categorised on the basis of their nitrogenous waste products. They are:
1. Ammonotelic animals are animals which excrete nitrogenous wastes as ammonia.
2. Ureotelic animals are animals which excrete nitrogenous wastes as urea.
3. Uricotelic animals are animals which excrete nitrogenous wastes as uric acid.
Hence, Tadpole is ammonotelic because it lives in water and has a large volume of water that is needed for the elimination of ammonia. It can eliminate ammonia was rapidly as it is formed, into the surrounding water.
Adult frog is ureotelic because urea is far less toxic than ammonia and can be concentrated in the urine and excreted at slower rate.

Blood enters the kidney via the renal artery. Urea is removed from the blood by the kidneys. Hence, when blood leaves the kidney via a renal vein, the amount of urea is less in blood compared to the level of urea in blood contained in any other blood vessel.

The cells lining the proximal convoluted tubule are well adapted for reabsorption of materials from the filtrate. The cells reabsorb entire glucose, amino acids, most of the inorganic ions (Na⁺, K⁺, Cl ), much of the water as well as some urea from the filtrate.

Uricotelic organisms are the organisms which excrete nitrogenous waste substances in the form of uric acid, e.g., Lizard, some insects and birds.

Most people with one kidney live healthy, normal lives with few problems. In other words, one healthy kidney can work as well as two.

Excretion in cockroach is uricotelic meaning, it excretes uric acid or its salts as a result of deamination.

This phenomenon of filtration of glomerular blood through the filtration slits is called as glomerular filtration. It is also called as ultrafiltration because relatively larger molecules like proteins can not pass through filtration slits. Hence the mechanism of urine formation in nephron involves 'Ultrafiltration'

Thirst and frequent urination are two classic diabetes mellitus signs caused by high glucose levels in the blood. As kidneys work harder to filter out the glucose, they also pull more fluids from other tissues, which is why the patient urinates more often than usual. This is the way in which the body indicates that it needs to replenish the liquids it's losing. 

Vasopressin that is also called antidiuretic hormone released by hypothalamus for controlling the water and electrolyte balance in the kidney at the renal cortex.

Ultrafiltration and reabsorption in the kidney are carried out by its functional unit called nephron. Ultrafiltration occurs between the glomerulus and Bowman's capsule of the nephron.

Ultrafiltration, selective reabsorption, and passive absorption all occur in the kidneys during the process of urine formation specifically in the nephron.

Ultrafiltration means the diffusion of blood, including plasma to nephron to be filtered. Red blood cells and plasma protein cannot pass through ultrafiltration membrane because their size is too big.

Reabsorption includes the active and passive transport. Water is absorbed by osmosis or via aquaporin. Ions (e.g:Na+) is reabsorbed by active transport while glucose, amino acids, and small hydrophobic molecule can reabsorb by diffusion or facilitated diffusion. The process of reabsorption occurs in the renal tubule. 

Plasma is the liquid portion of the blood and thus carries nutrients and excretory products to their respective tissues and organs.

Micturition or urination is the process of expelling urine from the bladder. This act is also known as voiding of the bladder. The excretory system in humans includes a pair of kidneys, two ureters, a urinary bladder and a urethra.

Ornithine cycle helps in excretion. It helps in conversion of excess of amino acids into urea in liver.The ammonium ions enter urea cycle and get converted into urea. The urea formed in liver is transported to kidney through circulation and finally gets excreted.

Reptiles or birds, that excrete most of their waste nitrogen in the form of uric acid, are called uricotelic. Uric acid is formed from ammonia mostly in the liver and to some extent in the kidneys. The process is highly energy dependant, but is much less toxic than both ammonia and urea and it is almost insoluble in water and can be eliminated from the body in nearly a solid state, saving a lot of water. Since kidneys can handle the nitrogenous wastes only in solution, reptiles and birds pass a dilute solution of uric acid into the cloaca, where water is absorbed and solid uric acid is eliminated along with faeces. 

Ammonia is the most toxic form and requires large amount of water for its elimination, whereas uric acid, being the least toxic

• The excretory organ of cockroach is the Malpighian tubules. It is found at the junction of the midgut and hindgut and is about 150 in number.
• Almost every segment of the earthworm has a pair of excretory organs, known as nephridia. Each nephridium is made up of a coiled tube that opens into the body cavity.
• Rabbit has a pair of kidneys on either side of the body as an excretory organ. So, the correct answer is option B.

Urine is a transparent, light yellow liquid with a slightly acidic pH (average pH 6.0). The colour of urine is caused by the pigment urochrome, which is a breakdown product of haemoglobin from worn out red blood corpuscles.. Urochrome and the degradation products of bilirubin (urobilin) make urine yellow coloured.