Class 11 Biology WBCHSE Excretory Products And Their Elimination Question And Answers
Question 1. With respect to location, what is the difference between both kidneys? Give the reason.
Answer:
Both kidneys are present between the 12th thoracic vertebra and the 3rd lumbar vertebra, enclosed by the peritoneum. However, the right kidney is placed slightly lower than the left kidney. This is due to the presence of the liver towards the right side, just below the diaphragm.
Question 2. Aquatic animals are generally ammonotelic, whereas terrestrial animals are not—explain.
Answer:
Aquatic animals are generally ammonotelic, whereas terrestrial animals are not
Most of the aquatic animals are ammonotelic. These organisms produce ammonia as the main nitrogenous waste product. Ammonia requires large amount of water to be excreted from the body.
To remove lgm of ammonia about 300-500 ml of water is required. This much water is available only to the aquatic animals. Moreover, ammonia being highly soluble in water, diffuses out of the body surface, gills, etc., of the aquatic organisms.
It mixes with water, rendering itself harmless. On the other hand, terrestrial animals do not have such a large supply of water, that is required to remove ammonia. Hence, most of them are ureotelic or uricotelic.
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Question 3. How does JGA control GFR?
Answer:
When the rate of ultrafiltration decreases within the nephron, GFR also falls. At this point in time, JG cells, present within JGA, secrete renin. This renin increases the blood flow within the glomerulus, increasing the GFR to the normal limits.
Question 4. How does urine formation take place within DCT and collecting tubule, by the process of conditional reabsorption?
Answer:
Reabsorption of water and Na+ within the DCT and collecting tubule, depends upon several conditions or factors.
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These conditions or factors are discussed below—
Neurosecretory cells present within neurohypophysis secrete ADH hormone, which influences water reabsorption in DCT and collecting tubules. When the secretion of ADH decreases, the quantity of water in urine also increases, causing diuresis.
Reabsorption of water and Na+ within the DCT and collecting tubule is mainly regulated by the hormone, aldosterone, secreted by the adrenal cortex.
Therefore, hormone-regulated water reabsorption results in concentrated urine.
Question 5. Describe the relation between renin and angiotensin.
Answer:
The relation between renin and angiotensin
When GFR decreases, renin is secreted from the JG cells, which converts angiotensinogen to angiotensin-1 and further into angiotensin-2. This angiotensin-2 causes contraction of the blood capillaries of the glomerulus, thereby increasing the GFR.
Question 6. Describe the relation between angiotensin 2 and aldosterone.
Answer:
The relation between angiotensin 2 and aldosterone
Angiotensin 2 stimulates the adrenal cortex. This results in an increase in the synthesis and secretion of a mineralocorticoid hormone, called aldosterone. Aldosterone increases the Na+ reabsorption within the DCT. This increases both GBP and GFR.
Question 7. What are mesangial cells? What are their functions?
Answer:
Mesangial cells: The cells found in the middle region of the endothelium of glomerular capillaries and epithelium of Bowman’s capsule, are known as mesangial cells.
Functions:
- These cells are contractile and help in glomerular filtration.
- They are involved in renal secretion and absorption of immune complexes.
Question 8. Why does the colour of the urine become more yellow in summer?
Answer:
Normal coloration of urine is due to the presence of urobilin and urobilinogen. More water is lost from the body as sweat, in summer.
This results in the deficiency of water within the body. This makes the blood hypertonic in nature, thereby increasing the osmotic concentration in the blood. Due to this, secretion of ADH from neurohypophysis increases.
As a result, water reabsorption in DCT increases causing hypertonic urine to be released. The presence of less water causes a darker coloration of urine.
Question 9. Which nitrogenous waste product is excreted through the saliva?
Answer:
Urea is a nitrogenous waste product excreted
through the saliva.
Question 10. What are the conditions known when glucose concentrations in the blood as well as in the urine exceed the normal level?
Answer:
When glucose concentration increases in the blood, the condition is known as hyperglycemia. When glucose concentration increases in the urine, the condition is known as glucosuria.
Question 11. What is the condition known as, when the glomerulus undergoes inflammation?
Answer:
The condition when the glomerulus undergoes inflammation is called glomerulonephritis
Class 11 Biology WBCHSE Excretory Products And Their Elimination Very Short Answer Type Questions
Question 1. Define excretion.
Answer:
Excretion
The process by which harmful metabolic wastes and other byproducts are eliminated from the body, is called excretion.
Question 2. Define ammonotelism.
Answer:
Ammonotelism
Ammonotelism is the process of excretion of nitrogenous wastes, mainly in the form of ammonia.
Question 3. What are uriotelic animals?
Answer:
Uriotelic animals
Animals who excrete uric acid as the main nitrogenous waste material are called uricotelic animals.
Question 4. What is meant by the term osmoregulation?
Answer:
Osmoregulation
Osmoregulation is the process of maintaining water and salt balance in the body.
Question 5. What is hilum in the kidneys?
Answer:
Hilum in the kidneys
Hilum is a fissure in the concave region of the kidney where renal arteries enter into and ureter and veins exit out of the kidney.
Question 6. What are medullary pyramids?
Answer:
Medullary pyramids
The conical-shaped compartments that make up the renal medulla are known as medullary pyramids.
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Question 7. Name the fine branch of the renal artery that brings blood to Bowman’s capsule for filtration.
Answer:
Afferent arteriole
Question 8. What are cortical nephrons?
Answer:
Cortical nephrons
Cortical nephrons are nephrons found in the renal cortex which have a shorter loop of Henle.
Question 9. What are peritubular capillaries?
Answer:
Peritubular capillaries
A network of capillaries, formed by branching of efferent arteriole, that surrounds the segments of its own nephron and adjacent nephrons, are known as peritubular capillaries.
Question 10. What is vasa recta?
Answer:
Vasa recta:
The series of vascular loops, formed by branching of the efferent arteriole, that surrounds the loop of Henle, are called the vasa recta.
Question 11. Why is glomerular filtration also called ultrafiltration?
Answer:
Ultrafiltration is the process by which colloidal substances are separated from the solvent using a semipermeable membrane by application of pressure. Glomerular filtration is a similar process where impurities are separated from blood under high pressure of glomerular capillaries. Here, membrane of glomerular capillaries and Bowman’s capsule serve as the semipermeable membranes.
Question 12. Define glomerular filtration rate (GFR).
Answer:
Glomerular filtration rate (GFR)
Glomerular filtration rate (GFR) is the volume of filtrate obtained through glomerular filtration per unit time.
Question 13. What is tubular secretion?
Answer:
Tubular secretion
Tubular secretion is the secretion of materials, such as H+, K+, etc., from peritubular capillaries to renal tubular lumen, when the filtrate passes through the DCT. It occurs through the active transport process.
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Question 14. Which part of the kidney tubule has brush-bordered epithelium?
Answer:
Proximal convoluted tubule.
Question 15. What are osmoreceptors?
Answer:
Osmoreceptors
The osmoreceptors are the sensory receptors present in the hypothalamus, which respond to changes in the osmotic pressure of the blood.
Question 16. What is the main excretory product of reptiles?
Answer:
Uric acid
Question 17. How does sweat regulate body temperature?
Answer:
Sweat provides a cooling effect on the body. It is released out on the surface of the skin and is evaporated using latent heat from the body. This lowers the body temperature.