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2nd year Biology ‘Homeostatis’ Short Questions

2nd year  Biology ‘Homeostatis’ Short Questions

Q.1. Why more water is required for the excretion of ammonia.

Ans. It is highly soluble in water and rapidly diffuse across the plasma membrane. Ammonia is toxic for the organism. Its toxicity is reduced when diluted with large quantities of water due to this reason more water is required for excretion.

Q.2. Where urea is produces and why ATP is required for the process?

Ans. Urea is produced in the liver. NH3 combines with CO2 during this process ATP is required. Mammals, amphibians, shark and some bony fishes also excreted urea.

Q.3. Why water is not required for the excretion of uric acid?

Ans. It has extremely low solubility in water due to this water is not required for the excretion of uric acid. Formation of uric acid requires ATP.

Q.4. In which form the uric acid is excretion out of the body?

Ans. The suspension of uric acid is discharged in the form of thick paste or solid pellets. Uric acid is excreted by insects reptiles and bird.

Q.5. How much urea is less soluble than ammonia in water?

Ans. Urea is relatively less soluble in water 100,000 times less toxic than NH3.

Q.6. Give the route of excretion from the soft bodied animals and fishes?

Ans. In soft bodied animal ammonia is excreted from the body surface. In fish, most of the ammonia is excreted through gills as ammonium ions.

Q.7. What are the excretory organs of earthworm?

Ans. The excretory organs of earthworm are metanephridia which are arranged segmentally.

Q.8. What is metanephridium?

Ans. Each metanphridiumus coiled tube which is surrounded by capillaries. One end of metanephridium open in coemolic fluid where as other end opens on body surface through nephridiopore. Waste materials along with water are absorbed from the coemolic fluid passes through coiled part reabsorption of water takes place and remaining part is excreted through nephridiopore to outside the body.

Q.9. What is liver?

Ans. Liver is large reddish brown exocrine gland located in abdomen just below the diaphragm. Liver has bladder like gall bladder which stores bile and pour this bile into duodenum by the help of bile duct.

Q.10. What is the role of the liver for the metabolism of carbohydrates?

Ans. Liver maintain the level of glucose in blood. If blood contains excess glucose then glucose is stored in liver in the form of glycogen. If blood contains less glucose then stored glycogen is converted in glucose and release in blood. If glycogen is unavailable then liver converts amino acid or lipids into glucose and release in ton blood. Liver also converts lipids into fats and stores it.

Q.11. What is deamination and in which cycle the ammonia is converted into urea?

Ans. In liver break down of amino acids takes place. First amino group (NH4) is separated from amino acids and this process is called diamination then CO2 reacts with ammonia in ornithine cycle and converted into urea. This urea is released in blood circulation and excreted through kidneys.

Q.12. Describe the detoxification role of liver?

Ans. Liver also neutralizes many toxic substance such as hydrogen peroxide which is produced during metabolism is broken down into H2O and O2 by the help of enzyme catalase.

Q.13. How gall stones are formed?

Ans. Liver synthesizes cholesterol in excess amount forms gall stones in gall bladder.

Q.14. How liver help in the maintenance of body temperature for homeostatis?

Ans. Due to high metabolic are in liver heat is produced which helps in maintaining body temperature.

Q.15. For which vitamins the liver act as a reservoir?

Ans. Liver also stores many vitamins such as A, B and D.

Q.16. What is ultrafiltration and where it occurs?

Ans. During this process when blood passes through glomerulous, its plasma filters and diffuses into Bowman’s capsule. Filtration occurs due to high hydrostatic pressure in glomerulous is called ultrafiltration. This filtrate contains all molecules except plasma, proteins and blood cells.

Q.17. From where the reabsorption of glucose, amino acid, water and salt occur in the nephron?

Ans. When filtrate passes through proximal convoluted tubule, glucose, amino acids, water and salts are reabsorbed in per tubular network.

Q.18. Compare the role of ascending and descending limb of henel?



In ascending limb of loop of Henle active absorption of sodium and chloride ions takes place. Sodium and chloride ions move out from filtrate into interstitial fluid and then taking up by the blood.


When filtrate passes through descending limbs of loop of Henle reabsorption of water and sodium takes place.

Q.19. What is the function of distil convoluted tubule of nephron?

Ans. In distal convoluted tubule concentration of various salts in adjusted under influence of hormones. The filtrate now almost urine and collected in collecting dust.

Q.20. How many types of counter current mechanism are there?

Ans. There are two counter current system are operating.

1. One of the counter current is termed as counter current multiplier loops of Henle.
2. The other counter current system is consists of those blood vessels which run parallel to loop of Henle and are called Vasa Recta.

Q.21. How counter current multiplier perform its responsibilities?

Ans. In counter current multiplier loops of Henle the filtrate passes through descending limbs of loop of Henle, reabsorption of water takes place from filtrate and it becomes hypertonic then the interstitial fluid. In ascending limb of loop of henle, sodium and chloride ions are actively reabsorbed from the filtrate and it becomes hypotonic. Sodium and chloride ions removed from ascending limbs slowly diffuse bact to descending limbs.

Q.22. What is the role of vasa recta?

Ans. The outer counter current system is consists of those blood vessels which run parallel to loop of Henle and are called Vasa Recta. The blood supply to vasa recta provides oxygen and nourishments to the tissues of medulla it also takes away water absorbed from the filtrate.

Q.23. What are the adaptations of kidneys for the conservation of water?

Ans. Kidneys are adapted for the conservation of water. For this purpose two types of nephrons are found in kidneys. Such as cortical nephrons which have sorter lop of henle where the reabsorption of water is lower and Juxtamedullary nephrons which have longer loop of henle which extend up to medulla. In these nephrons reabsorption of water is higher. If kidney has larger number of Juxtamendullary nephrons there is greater conservation of water.

Q.24. How many types of nephrons are there?

Ans. There are two types of nephrons.

1. Cortical Nephrons: Which have shorter loop of Henle where the reabsorption of water is lower.

2. Juxtamedullary Nephrons: Which have longer loop of Henle which extend up to medulla. In these nephrons reabsorption of water is higher.

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