Question 1

Q1: Define Glomerular Filtration Rate (GFR)

Accepted Answer

Glomerular Filtration Rate (GFR) is defined as the amount of filtrate formed by the kidneys per minute. In a healthy individual, the GFR is approximately 125 ml/minute, which amounts to 180 litres per day.

Question 2

Q10: What is the significance of juxta glomerular apparatus (JGA) in kidney function?

Accepted Answer

The Juxta Glomerular Apparatus (JGA) has a significant role in regulating kidney function, particularly the Glomerular Filtration Rate (GFR). The JGA is a specialized structure located where the distal convoluted tubule comes into contact with the afferent arteriole. Its primary significance is its...

Question 3

Q11: Name the following: (a) A chordate animal having flame cells as excretory structures (b) Cortical portions projecting between the medullary pyramids i...

Accepted Answer

(a) Amphioxus (a cephalochordate) (b) Columns of Bertini (or Renal columns) (c) Vasa recta

Question 4

Q12: Fill in the gaps: (a) Ascending limb of Henle's loop is ________ to water whereas the descending limb is ________ to it. (b) Reabsorption of water fro...

Accepted Answer

(a) Ascending limb of Henle's loop is impermeable to water whereas the descending limb is permeable to it. (b) Reabsorption of water from distal parts of the tubules is facilitated by hormone ADH (Antidiuretic hormone). (c) Dialysis fluid contain all the constituents as in plasma except nitrogenous...

Question 5

Q2: Explain the autoregulatory mechanism of GFR.

Accepted Answer

The kidneys have an efficient built-in mechanism for the regulation of the glomerular filtration rate (GFR). This is carried out by the Juxta Glomerular Apparatus (JGA), which is a special sensitive region formed by cellular modifications in the distal convoluted tubule and the afferent arteriole at...

Question 6

Q3: Indicate whether the following statements are true or false : (a) Micturition is carried out by a reflex. (b) ADH helps in water elimination, making t...

Accepted Answer

(a) True. The process of release of urine is called micturition, and the neural mechanism causing it is called the micturition reflex. (b) False. ADH (Antidiuretic Hormone) facilitates water reabsorption from the distal parts of the tubule, thereby preventing water loss (diuresis) and making the uri...

Question 7

Q4: Give a brief account of the counter current mechanism.

Accepted Answer

The counter current mechanism is a process that helps mammals produce concentrated urine. It primarily involves the Henle's loop and the vasa recta. 1.  Counter Current Flow: The flow of filtrate in the two limbs of Henle's loop is in opposite directions. Similarly, the flow of blood in the two limb...

Question 8

Q5: Describe the role of liver, lungs and skin in excretion.

Accepted Answer

Besides the kidneys, other organs like the liver, lungs, and skin also play a role in eliminating excretory wastes. 1.  Lungs: The lungs are the primary organs for the removal of carbon dioxide ($CO_2$), a major metabolic waste product. They excrete approximately 200 mL of $CO_2$ per minute and also...

Question 9

Q6: Explain micturition.

Accepted Answer

Micturition is the process of releasing urine from the urinary bladder. It is controlled by a neural mechanism known as the micturition reflex. The process involves the following steps: 1.  Urine formed by the nephrons is transported by the ureters to the urinary bladder, where it is stored. 2.  As...

Question 10

Q7: Match the items of column I with those of column II : Column I (a) Ammonotelism (b) Bowman's capsule (c) Micturition (d) Uricotelism (e) ADH Column II...

Accepted Answer

The correct matches are as follows:    (a) Ammonotelism - (iii) Bony fish (Bony fishes excrete ammonia as their primary nitrogenous waste.)    (b) Bowman's capsule - (v) Renal tubule (The renal tubule begins with the double-walled Bowman's capsule.)    (c) Micturition - (iv) Urinary bladder (Micturi...

Question 11

Q8: What is meant by the term osmoregulation?

Accepted Answer

Osmoregulation is the biological process by which an organism maintains the constant osmotic pressure of its body fluids by regulating the water and salt concentrations. It is concerned with the maintenance of ionic and fluid volume balance within the body. In vertebrates, the kidneys are the primar...

Question 12

Q9: Terrestrial animals are generally either ureotelic or uricotelic, not ammonotelic, why?

Accepted Answer

Terrestrial animals are generally not ammonotelic due to the high toxicity of ammonia and the large amount of water required for its elimination.  Ammonia, the primary nitrogenous waste in many aquatic animals, is highly toxic and must be diluted with a large volume of water to be excreted safely. T...

NCERT Solutions