31 Years NEET Previous Year Questions: Excretory Products & Their Elimination - 1 - NEET MCQ

Diabetes mellitus leads to a complex disorder called prolonged hyperglycemia, which is associated with loss of glucose through urine known as glycosuria and when the cell are unable to utilize carbohydrates for energy instead they use fats & proteins, and degradation of these fats produces ketone bodies.  The presence of these ketone bodies in urine is known as ketonuria.

The counter current mechanism helps to maintain a concentration gradient in the medullary mterstitium. The proximity between the Henle’s loop and vasa recta, as well as the counter current in them help in maintaining an increasing osmolarity towards the inner medullary interstitium, i.e., from 300 mOsmoIL-1 in the cortex to about 1200 mOsmolL-1 m the inner medulla. This gradient is mainly caused by NaCl and urea. Presence of such interstitial gradient helps in an easy passage of water from the collecting tubule thereby concentrating the filtrate (urine).

(i) Glomerular capillary pressure (45 mm Hg) favours filteration. (ii) The colloidal osmotic pressure (due to plasma proteins, particularly albumin) acts against filteration. Its value is ~20 mmHg. (iii) The filterate pressure due to the glomerular filterate filled in the Bowman’s capsule also acts against filteration. Its value is ~10 mmHg.
Net filteration pressure = 45 – (20 + 10) mm Hg = 15 mm of Hg  (10 – 20 mm of Hg)

Ornithine cycle: The urea cycle (also known as the ornithine cycle) is a cycle of biochemical reactions that produces urea ((NH₂)₂CO) from ammonia(NH3).
CO₂ and ammonia are the pair of wastes removed from the blood in Ornithine cycle. Urea is formed in Ornithine cycle of urea cycle and urea is formed of two molecules of ammonia and one molecule of CO₂. 
Most of the urea is produced in the liver. The liver cells continuously release urea into the blood and kidneys withdraw it from the blood to excrete it in urine.

Some animals have dual behaviour of excretion eg. earthworm. It excretes ammonia (hence called ammonotelic) when enough water is available but excretes urea (ureotelic) in dry conditions.

Bowman’s gland sare located in the olfactory epithelium of our nose. 

Lysozyme is an antibacterial agent which is secreted by the major salivary glands.

Characteristics of certain desert animals such as kangaroo, rat are -

• They feed on dry seeds and do not require drinking water.
• They excrete very concentrated urine and do not use water to regulate body temperature. 

The correct option is A There will be no micturition
Stretch receptors on the wall of urinary bladder sends impulse to CNS and in response, motor signals sent by CNS, initiates bladder contraction to release urine. It regulates micturition. So, if stretch receptors of urinary bladder wall are totally removed, then there will be no micturition.

Uric acid is the chief nitrogenous component of the excretory product of cockroach. Animals which live in dry conditions have to conserve water in their bodies. Therefore, they synthesise crystals of uric acid trom ammonia. Uric acid crystals are non-toxic and can be retained in the body for a considerable time. Uricotelic animals include most insects e.g. cockroach, reptiles and birds.

Urine formation involves three main process called, glomerular filtration, reabsorption and secretion. A comparison of the volume of the filtrate formed per day (which is 180 litres per day) with that of urine released (about 1.5 litres) suggest that nearly 99 percent of the glomerular filtrate is resorbed by the renal tubules. The descending limb of loop of Henle is permeable to water but impermeable to electrolytes.
The ascending limb is impermeable to water but allows transport of electrolytes.
Reabsorption of sodium ions and water takes place in distal convoluted tubule.
Also, it is capable of reabsorption of HCO₃.

The principal nitrogenous excretory compound in humans is urea. It is synthesized in the mitrochondrial matrix and cytosol of liver cells and eliminated through kidneys.

Tissue and blood group matching are essential before undertaking kidney transplant. Even if kidney transplant is proper, the recipient may need to take immuno suppresant all his/her life. The ability of body to differentiate self and nonself and the cell-mediated immune response is responsible for graft rejection.

The medulla is divided into a few conical masses called medullary pyramids projecting into the calyces.
The cortex extends in between the medullary pyramids as renal columns called Columns of Bertini. Hence convoluted tubules are not a part of the renal tubule.
The DCTs of many nephrons open into a straight tube called collecting duct, many of which converge and open into the renal pelvis through medullary pyramids in the calyces. Hence Collecting ducts is the part of renal pelvis
So, the correct answer is 'Convoluted tubules'.

A large portion of oxygen is left unused in the human blood even after its uptake by the body tissues. This O₂ acts as a reserve during muscular exercise.

Glome podocytes are highly specialized cells with a complex cytoarchitecture plays a major role in establishing the  selective permeability of glomerular filtration barrier.

When some one drinks lots of water, kidney release of ADH is suppressed.

An uricotelic organism produces uric acid as a result of de-amination. Examples of such organism are birds and insects.

In the frog, each kidney is composed of several structural and functional units called uriniferous tubule or nephrons. Two ureters emerge from the kidneys in the male frogs. The ureters act as a urinogenital duct which opens into the cloaca. The thin-walled urinary bladder is present ventral to the rectum which opens in the cloaca.

Nearly all the essential nutrients, and 70-80 percent of electrolytes and H₂O are reabsorbed by proximal convoluted tubules.

Those animals that excrete ammonia are called as ammonotelic, eg. aquatic amphibia. Those animals that excrete urea are called as ureotelic, eg. frog, humans.
Those animals that excrete uric acid are called as uricotelic, eg. pigeon, lizards, and cockroach.

 The amount of the filtrate formed by the kidneys per minute is called glomerular filtration rate (GFR). GFR in a healthy individual is approximately 125 ml/ minute, i.e., 180 litres per day. A fall in GFR can activate the JG cells to release renin which can stimulate the glomerular blood flow and thereby the GFR back to normal. Renin converts angiotensinogen in blood to angiotensin I and further angiotensin II. Angiotensin II being powerful vasoconstrictor increases the glomerular blood pressure and thereby GFR

Adult frog and human exhibit ureotelism because there excretory waste product is urea.

A – Adrenal gland – located at the anterior part of kidney, secrete Catecholamines which stimulate glycogen breakdown.

Option ( c) is correct answer. 

Explanation :- 

As Housefly - Malpigian Tubules - Uric acid

Rohu - Kidney - Ammonia

Peacock - Kidney - Uric acid

Salamander - Kidney - Urea