Explore topic-wise InterviewSolutions in .

The correct answer is (b) False

The best I can explain: The URINE formed is a LIGHT yellow coloured watery fluid that is slightly acidic and has a characteristic odour. On average, 25-30 grams of urea is EXCRETED out PER DAY.

Correct choice is (a) Smooth muscle cells

Best EXPLANATION: Juxtaglomerular cells are modified smooth muscle cells of the afferent renal arteriole which secrete renin. This renin is a hormone CUM enzyme. It goes from the kidney to the liver. When the liver detects renin, then it RELEASES ANGIOTENSINOGEN which CHANGES into angiotensin I.

The CORRECT answer is (d) Anuria

The EXPLANATION is: The condition of no urine formation is KNOWN as anuria. The condition of LESS urine formation is known as oliguria while excessive urine formation is known as polyuria.

Correct answer is (b) False

To explain I would SAY: Nearly 99 per cent of the filtrate that PASSES through our RENAL tubules EVERY minute is being reabsorbed by our blood capillaries and the renal tubules themselves. Approximately 180 litres of filtrate is formed per day but only 1.5 litres of urine is released. Therefore, a huge amount of filtrate is being reabsorbed every minute.

Right CHOICE is (C) Three

The best I can explain: Three layers of the GLOMERULAR epithelium of the Malpighian corpuscle are involved in the filtration of the blood. These layers include the endothelium of glomerular blood vessels, the epithelium of BOWMAN’s capsule and a basement membrane between these TWO layers.

Correct option is (b) Glomerular filtration rate

Explanation: GFR stands for the Glomerular filtration rate. It is the AMOUNT of the filtrate formed by the kidneys PER MINUTE. It PLAYS an IMPORTANT role in determining the health status of the kidneys.

Right option is (a) A voluntary SIGNAL from the CNS

To EXPLAIN I WOULD SAY: Urine is stored in the urinary bladder until a voluntary signal comes from the Central nervous system. The receptors PRESENT on the urinary bladder receive these signals.

Right answer is (c) Urethral sphincter

Best explanation: Urethral sphincter CAUSES the RELEASE of URINE to the outside of the body. This process starts when the central nervous system passes on the motor MESSAGES to the smooth muscles of the bladder. This signal INITIATES their contraction. Simultaneously, relaxation of the urethral sphincter takes place which causes the release of the urine.

The CORRECT choice is (a) ANF

To ELABORATE: ANF or the ATRIAL Natriuretic Factor is a VASODILATOR and can decrease BLOOD pressure. It acts as a check on the renin-angiotensin mechanism that is activated when the glomerular filtration rate decreases.

Right OPTION is (b) False

To explain: Aldosterone is a hormone which is released from the adrenal cortex. It increases the reabsorption of SODIUM ions and WATER from the latter PARTS of the nephrons, such as the DCT and the collecting tube.

Right CHOICE is (c) DCT

To elaborate: Selective secretion of hydrogen and potassium ions and AMMONIA maintain the PH and ALSO the sodium-potassium BALANCE in the body by reabsorption of bicarbonate ions.

Correct answer is (a) HENLE’s LOOP and vasa recta

Explanation: Mammals can produce concentrated URINE. The Henle’s loop and vasa recta present in the mammals play a significant role in the CONCENTRATION of the urine.

Right choice is (a) CAPSULAR hydrostatic pressure

To EXPLAIN I would SAY: CHP stands for Capsular hydrostatic pressure. It is the pressure CAUSED by the filtrate or the fluid that reaches into BOWMAN’s capsule which resists filtration.

Correct CHOICE is (c) Deep in the medulla

Easy EXPLANATION: In some of the NEPHRONS in the kidney, the loop of Henle is very long and runs deep into the medulla. These nephrons dipping into the medullary REGION are KNOWN as juxtamedullary nephrons.

Right CHOICE is (a) True

Explanation: Starfishes are aminotelic organisms as they excrete amino ACIDS directly into the urine. Hippuric acid is an excretory waste formed by the combination of benzoic acid and glycine in MAMMALS.

Right answer is (b) Ammonia

To explain I would say: Ammonia is the most toxic form of nitrogenous waste as it is corrosive. Also, it REQUIRES LARGE amounts of ENERGY for its elimination. Ammonia also needs a huge AMOUNT of WATER for its removal from the body.

Right OPTION is (d) REMOVAL of urea in the blood by ARTIFICIAL means

Easy explanation: Urea from blood can be removed by artificial means if a person is not able to excrete out urea. It is removed by a process called haemodialysis in which blood is drained from a convenient artery into a dialysing unit called an artificial KIDNEY.

Correct OPTION is (c) Glomerulonephritis

Easy explanation: Inflammation of glomeruli is REFERRED to as glomerulonephritis. The inflammation of URINARY bladder, nephron, and pelvis of the kidney is referred to as CYSTITIS, NEPHRITIS, and Pyelonephritis respectively.

Correct choice is (c) By both active and passive TRANSPORT

The best explanation: The ascending limb of Henle’s loop is impermeable to water but allows the transport of electrolytes actively or passively. Moreover, the width of this TUBULE ALSO varies as it has a thin segment and a thick segment of the ascending limb.

Right option is (C) Homoeostasis

For explanation: Osmoreceptors are activated by the blood VOLUME, the body FLUID volume and the ionic CONCENTRATION. When these elements are within the NORMAL range, or during homeostasis, the osmoreceptors are not active.

Right OPTION is (a) It does not maintain the pH

For explanation I would say: PCT is responsible for maintaining the pH of the body fluids. It is also responsible for maintaining the IONIC balance of the body fluids by selective secretion of hydrogen ions, ammonia, and POTASSIUM ions into the FILTRATE. It also absorbs HCO3^– ions to maintain the ionic balance.

Right answer is (B) Decreases blood PRESSURE

The BEST explanation: ADH or the antidiuretic hormone is also known as vasopressin. Vasopressin stimulates water reabsorption from the kidneys, prevents DIURESIS, decreases perspiration and increases blood pressure.

The correct OPTION is (b) Brush border cuboidal cells

Easy explanation: PCT is LINED by simple cuboidal brush border epithelium which INCREASES the surface AREA for reabsorption. Nearly all of the essential NUTRIENTS are reabsorbed here.

Correct choice is (d) Nitrogenous WASTES

Explanation: Substances like GLUCOSE, amino ACIDS, sodium ions, etc., in the filtrate, are reabsorbed actively whereas the nitrogenous wastes are absorbed by passive TRANSPORT.

Correct answer is (d) JG cells

The best I can explain: A fall in the GFR can ACTIVATE the JG cells to release renin which can STIMULATE the glomerular BLOOD flow and thereby the GFR back to normal.

Right choice is (a) Neurohypophysis

Easy explanation: Vasopressin or the antidiuretic hormone (ADH) is released from the neurohypophysis or the posterior lobe of the PITUITARY GLAND. OXYTOCIN is also released from here. ADH PREVENTS diuresis.

The correct CHOICE is (c) CO2

Easiest explanation: Carbon dioxide is not the excretory waste of the liver. Our liver secretes bile which contains pigments like bilirubin and biliverdin, whose excess can be a waste product. Some other excretory products of the liver are cholesterol, degraded STEROID HORMONES, vitamins, and drugs. These WASTES tend to pass along with the DIGESTIVE wastes.

Correct choice is (b) False

The best explanation: COLLECTING duct PLAYS a significant ROLE, along with PCT and DCT in the secretion of hydrogen and potassium ions to MAINTAIN the pH and ionic balance of the blood.

The correct choice is (B) By the passive transport

The best I can explain: REABSORPTION of water occurs passively in the initial SEGMENTS of the nephron. During urine formation, the TUBULAR cells secrete some substances into the filtrate to ENHANCE the reabsorption process.

The CORRECT answer is (a) Glomerular FILTRATION

To elaborate: The first step in the urine FORMATION is the filtration of blood, which is carried out by the glomerulus and is THEREFORE known as glomerular filtration.

Correct option is (B) Renal vein

The explanation is: Renal vein carries the blood with a MINIMUM amount of UREA while HEPATIC vein carries the blood having a maximum amount of urea.

Right CHOICE is (a) Henle’s loop

The best I can EXPLAIN: The highly coiled proximal convoluted tubule leads to a HAIRPIN SHAPED Henle’s loop which has a descending and an ASCENDING limb. The ascending limb continues further to another tubule.

The correct answer is (b) Proximal Convoluted Tubule

For explanation I would SAY: PCT stands for Proximal Convoluted Tubule. The renal corpuscle CONTINUES further to form a HIGHLY COILED network of PCT. BRUSH bordered cuboidal epithelium is present in PCT.

Correct choice is (a) Hilum

Best EXPLANATION: Through the hilum, the nerves, the ureters and the blood vessels enter the KIDNEYS. The hilum is a notch which is present TOWARDS the centre of the inner concave surface of the KIDNEY.

Right answer is (B) False

To elaborate: In most of the invertebrates, KIDNEYS are not present for excretion. Their excretory structures are simple tubular forms like nephridia, flame CELLS, etc. It is the vertebrates who have complex tubular ORGANS called kidneys.

The correct answer is (d) Oxygen

Explanation: Oxygen is not accumulated by the body of LIVING organisms as this is required by the cells to perform respiration. Also, it is not a waste product of the cells. Animals ACCUMULATE ammonia, UREA, uric ACID, carbon dioxide, water, and ions like Na^+, K^+, Cl^–, PHOSPHATE, sulphate, etc., by certain metabolic activities.

Correct answer is (d) Micturition

To explain I WOULD say: The process of release of urine is called micturition and the NEURAL MECHANISMS causing it is called micturition reflex. An adult HUMAN excretes about 1 to 1.5 litres of urine per day.

Correct ANSWER is (d) ASCENDING limb of Henle’s LOOP

The EXPLANATION is: Reabsorption of water is minimum in ascending limb of Henle’s loop as it is impermeable to water which means that it does not allow the movement of water through itself.

Right CHOICE is (d) Juxta-medullary nephrons

Explanation: In desert mammals, juxtamedullary nephrons are present because they have a very long LOOP of HENLE which HELPS in the reabsorption of water as more as possible.

The correct OPTION is (a) Efferent arteriole

Best explanation: The peritubular CAPILLARIES emerge from the efferent arteriole which INITIALLY emerges out of GLOMERULUS. This arteriole forms a fine capillary network around the renal tubule which is known as peritubular capillaries. These capillaries further surround the loop of Henle.

Correct ANSWER is (C) 120 g

Easiest explanation: Each kidney of an adult human MEASURES for about 10-12 cm in length, 5-7 cm in width, and 2-3 cm in THICKNESS with an AVERAGE weight of 120-170 grams.

Right option is (c) ANF

The EXPLANATION is: EPINEPHRINE, which is released from the adrenal medulla, ADH or vasopressin, which is released from the POSTERIOR pituitary gland and ANGIOTENSIN II lead to the constriction of blood VESSELS. They are vasoconstrictors.