Mix Examples- Excretory Products and their Elimination Questions in English

(C) The blood leaving the kidney via the renal vein is significantly lower in urea compared to the blood entering the kidney via the renal artery.
This is because the primary function of the kidney is to filter metabolic wastes,specifically urea,from the blood.
While the blood also contains less $O_2$ and glucose due to the metabolic demands of the kidney tissue,the reduction in urea concentration is the most characteristic and significant change resulting from the excretory process.

(D) The correct answer is $D$.
Kidneys are primary excretory organs responsible for the filtration of blood,excretion of nitrogenous wastes,maintenance of water and electrolyte balance (osmoregulation),and regulation of blood volume and blood pressure.
The destruction of dead blood corpuscles (specifically red blood cells) is primarily carried out by the spleen,which is known as the 'graveyard of RBCs',and the liver.
Therefore,the destruction of dead blood corpuscles is not a function of the kidneys.

(D) The correct answer is $D$. The $Vasa$ $deferens$ (or sperm duct) is a part of the male reproductive system in rabbits. It arises from the $cauda$ $epididymis$ and transports sperm to the urethra. This structure is exclusively found in males and is absent in females.

(A) . Loop of Henle plays a significant role in the concentration of urine $(A-5)$.
$B$. Renal artery carries oxygenated blood into the kidney for filtration $(B-1)$.
$C$. Proximal convoluted tubule $(PCT)$ is the primary site where a considerable amount of electrolytes and water are reabsorbed $(C-2)$.
$D$. Glomerulus is the site of ultrafiltration of blood $(D-4)$.
$E$. Distal convoluted tubule $(DCT)$ is the main site for the secretion of ions like $H^+$ and $K^+$ to maintain $pH$ and ionic balance $(E-3)$.
Therefore,the correct sequence is $A-5, B-1, C-2, D-4, E-3$.

(B) The human body requires water for various physiological processes, including thermoregulation, digestion, and the excretion of metabolic wastes. While the exact requirement varies based on activity level, climate, and diet, a healthy adult typically requires approximately $2$ to $3$ litres of water per day. Among the given options, $5$ litres is the most reasonable upper limit for daily intake under normal physiological conditions, as $1$ litre is insufficient and $6$ or $10$ litres are generally excessive for a standard human body.

(C) In cold and wet seasons,the ambient temperature is low,which reduces the rate of perspiration (sweating).
Since less water is lost from the body through sweat glands,the body maintains water balance by increasing the volume of urine excreted by the kidneys.
Therefore,the correct option is $C$.

(D) Fresh urine is generally acidic and does not have a strong ammonia smell.
However,when urine is left to stand (stale urine),bacteria from the environment or skin contaminate it.
These bacteria break down the urea present in the urine into ammonia $(NH_3)$ and carbon dioxide.
The ammonia then reacts with water and other components to form ammonium carbonate,which further releases ammonia gas,causing the characteristic pungent smell.
Therefore,all the mentioned processes contribute to the smell of stale urine.

(A) Urine typically becomes cloudy due to the precipitation of phosphates when the alkalinity of the urine increases. Additionally,a bacterial infection can also cause urine to appear cloudy due to the presence of bacteria,white blood cells,or pus. However,the primary physiological cause related to chemical changes is the increase in alkalinity. Given the options provided,if we consider both factors,the most comprehensive answer is that cloudiness is associated with increased alkalinity or infection.

(B) The correct answer is $B$.
In the proximal convoluted tubule $(PCT)$,glucose,amino acids,and certain vitamins are reabsorbed via active transport,which requires the utilization of energy $(ATP)$.
Option $A$ is correct as the peritubular capillaries forming a network around the loop of Henle are known as vasa recta.
Option $C$ is correct because the ascending limb of the loop of Henle is impermeable to water but permeable to electrolytes.
Option $D$ is correct as freshwater fishes live in a hypotonic environment and must excrete large amounts of dilute (hypotonic) urine to maintain osmotic balance.

(A) The correct matching is as follows:
$(i)$ Ultrafiltration occurs in the Malpighian corpuscles (glomerulus + Bowman's capsule).
$(ii)$ Concentration of urine is primarily the function of Henle's loop in the nephron.
$(iii)$ Transport of urine from the kidneys to the urinary bladder is performed by the ureters.
$(iv)$ Storage of urine occurs in the urinary bladder until micturition.
Thus, the correct sequence is $(i)-(d), (ii)-(a), (iii)-(b), (iv)-(c)$.

(A) Cholera is a severe diarrheal disease caused by the bacterium $Vibrio$ $\text{cholerae}$.
This infection leads to massive loss of water and electrolytes $(Na^+, Cl^-)$ from the body through stool.
Saline solution (Oral Rehydration Solution or intravenous saline) is administered to replace the lost water and electrolytes.
$Na^+$ ions are crucial for maintaining osmotic balance and preventing further dehydration by facilitating water retention in the body.
Therefore, $Na^+$ helps in preventing the loss of water from the body.

(A) The correct matching is as follows:
$a.$ Loop of Henle: Plays a significant role in urine concentration $(5)$.
$b.$ Renal artery: Carries blood to the kidney $(1)$.
$c.$ Proximal Convoluted Tubule $(PCT)$: Region where maximum reabsorption occurs $(2)$.
$d.$ Glomerulus: Filtration of blood $(4)$.
$e.$ Distal Convoluted Tubule $(DCT)$: Main site of secretion $(3)$.
Therefore,the correct sequence is $a-5, b-1, c-2, d-4, e-3$.

(D) The primary functions of the kidney include osmoregulation (maintaining water balance),regulation of electrolyte balance,and the excretion of metabolic waste products like urea,creatinine,and uric acid.
Urea formation (the Ornithine cycle) occurs in the liver,not the kidney. The liver converts toxic ammonia into urea,which is then transported to the kidneys for excretion. Therefore,urea formation is not a function of the kidney.

(D) The kidney performs several vital functions to maintain homeostasis in the body.
$1$. Ultrafiltration: This occurs in the glomerulus,where blood is filtered under high pressure to form a filtrate.
$2$. Selective reabsorption: This occurs in the renal tubules,where essential substances like glucose,amino acids,and water are reabsorbed back into the blood.
Therefore,both ultrafiltration and selective reabsorption are primary functions of the kidney.

(A) Diuresis is a physiological process characterized by an increased production and excretion of urine by the kidneys.
This condition can be caused by various factors,such as high fluid intake,the use of diuretics,or certain medical conditions like diabetes mellitus.
Therefore,the correct option is $A$.

(C) During cold and humid weather,the body does not need to lose water through sweat to maintain thermoregulation.
As a result,the rate of perspiration (sweating) is significantly reduced.
Since the total volume of water lost through the skin decreases,the body compensates by excreting the excess water through the kidneys.
This leads to an increased volume of urine production and more frequent urination.

(C) The correct classification is based on the primary nitrogenous waste excreted by the animals:
$1$. Ammonotelic animals excrete ammonia,which is highly toxic and requires large amounts of water. Examples include aquatic amphibians.
$2$. Ureotelic animals excrete urea,which is less toxic and requires moderate water. Examples include humans and adult frogs (terrestrial stage).
$3$. Uricotelic animals excrete uric acid,which is the least toxic and requires minimal water. Examples include birds (pigeon),reptiles (lizards),and insects (cockroach).
Therefore,option $c$ correctly categorizes these animals.

(B) Urine formation involves three main processes: Glomerular filtration,Reabsorption,and Tubular secretion.
$1$. Glomerular filtration occurs in the glomerulus,not the $DCT$.
$2$. Reabsorption occurs primarily in the renal tubules ($PCT$,Loop of Henle,$DCT$,and Collecting Duct),not the glomerulus.
$3$. Tubular secretion involves the active secretion of substances like $H^+, K^+$,and ammonia into the filtrate to maintain ionic and acid-base balance.
$4$. The $GFR$ (Glomerular Filtration Rate) is approximately $125 \ ml/min$ (or $180 \ liters$ per day),whereas $1100-1200 \ ml/min$ is the renal blood flow.

(C) $1$. Statement $(a)$: The table shows $162 \,g$ of glucose in the glomerular filtrate and $162 \,g$ reabsorbed,resulting in $0 \,g$ in the urine. This confirms glucose is completely reabsorbed. Statement $(a)$ is correct.
$2$. Statement $(b)$: The table shows $54 \,g$ of urea in the filtrate and $24 \,g$ reabsorbed,leaving $30 \,g$ in the urine. This indicates partial reabsorption. Statement $(b)$ is correct.
$3$. Statement $(c)$: Proteins are generally not filtered in significant amounts by the glomerulus. The presence of $0.1 \,g$ in urine is negligible and does not indicate active secretion. Statement $(c)$ is incorrect.
$4$. Statement $(d)$: The table shows $1.6 \,g$ of creatinine in the filtrate and $1.7 \,g$ in the urine,with $0 \,g$ reabsorbed. The increase from $1.6 \,g$ to $1.7 \,g$ indicates that creatinine is actively secreted into the renal tubules. Statement $(d)$ is correct.
$5$. Therefore,statements $(a), (b),$ and $(d)$ are correct.

(C) The kidneys filter approximately $180$ liters of blood plasma per day,which is the volume of the glomerular filtrate $(X = 180)$.
Out of this,only about $1.5$ liters of urine is excreted per day $(Y = 1.5)$.
This implies that nearly $99$ $\%$ of the filtrate is reabsorbed by the renal tubules back into the blood $(Z = 99)$.
Therefore,the correct values are $X = 180$,$Y = 1.5$,and $Z = 99$.

(D) The correct answer is $D$.
$1$. The descending limb of the loop of Henle is permeable to water but nearly impermeable to electrolytes,which helps in the concentration of filtrate.
$2$. The distal convoluted tubule $(DCT)$ is capable of reabsorption of $HCO_3^-$ and selective secretion of hydrogen ions $(H^+)$,potassium ions $(K^+)$,and ammonia $(NH_3)$ to maintain the $pH$ and sodium-potassium balance in the blood.
$3$. The collecting duct allows for the passage of small amounts of urea into the medullary interstitium to keep up the osmolarity and also secretes $H^+$ and $K^+$ ions.
$4$. The ascending limb of the loop of Henle is impermeable to water but allows the transport of electrolytes (like $Na^+$,$Cl^-$,and $K^+$) actively or passively. Therefore,the statement that it is impermeable to electrolytes is incorrect.

(C) An adult human excretes,on average,$1$ to $1.5$ liters of urine per day.
Approximately $25$ to $30$ grams of urea is excreted out per day by an adult human.
These values are standard physiological data provided in the $NCERT$ textbook under the chapter 'Excretory Products and their Elimination'.

(B) In the given diagram of the human excretory system:
$A$ represents the Adrenal gland,which is located at the anterior part of the kidney. It secretes hormones like catecholamines (epinephrine and norepinephrine) that stimulate glycogen breakdown (glycogenolysis) to increase blood glucose levels.
$B$ represents the Renal pelvis,which is a broad,funnel-shaped space inside the hilum.
$C$ represents the Medulla,which consists of renal pyramids.
$D$ represents the Cortex,which is the outer layer of the kidney.
Therefore,option $B$ is the correct description.

(D) The correct matching is as follows:
$(a)$ Ultrafiltration occurs in the Malpighian corpuscle (glomerulus + Bowman's capsule),which is $(iv)$.
$(b)$ Concentration of urine is primarily performed by the Henle's loop through the counter-current mechanism,which is $(i)$.
$(c)$ Transport of urine from the kidneys to the urinary bladder is carried out by the ureter,which is $(ii)$.
$(d)$ Storage of urine occurs in the urinary bladder,which is $(iii)$.
Therefore,the correct sequence is $a-iv, b-i, c-ii, d-iii$.

(D) Hypotonic urine refers to urine that has a lower solute concentration than blood plasma.
Hypertonic urine,on the other hand,is more concentrated than blood and possesses a higher osmotic pressure than the blood.
Producing hypertonic urine is the mechanism that helps in reducing the loss of water through urine.
Since the Assertion claims that hypotonic urine reduces water loss (which is false) and the Reason incorrectly defines hypotonic urine as more concentrated than blood (which is also false),both statements are incorrect.

(C) The correct matching is as follows:
$(a)$ Podocytes: These are specialized cells in the Bowman's capsule of the kidney that form filtration slits, which are essential for ultrafiltration.
$(b)$ Protonephridia: These are excretory structures found in organisms like Amphioxus (Cephalochordates).
$(c)$ Nephridia: These are the tubular excretory organs found in earthworms and other Annelids.
$(d)$ Renal calculi: These are stone-like masses formed in the kidney, typically composed of crystallised oxalates.
Therefore, the correct sequence is $(a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)$.

(A) The correct matches are as follows:
$1$. $(a)$ Ammonotelism: Excretion of ammonia, typically seen in aquatic animals like $(iii)$ Bony fish.
$2$. $(b)$ Bowman's capsule: The cup-shaped structure at the beginning of the $(v)$ Renal tubule.
$3$. $(c)$ Micturition: The process of releasing urine from the $(iv)$ Urinary bladder.
$4$. $(d)$ Uricotelism: Excretion of uric acid, seen in $(i)$ Birds.
$5$. $(e)$ $ADH$ (Antidiuretic Hormone): Regulates $(ii)$ Water reabsorption in the kidneys.
Thus, the correct sequence is: $(a-iii, b-v, c-iv, d-i, e-ii)$.

$(A)$ Glomerular filtration (or filtrate)
$(b)$ Nitrogenous wastes (or excretory substances)
Explanation:
$(a)$ The process of urine formation involves three main steps: glomerular filtration, tubular reabsorption, and tubular secretion. The net amount excreted is calculated as: $\text{Urinary excretion} = \text{Glomerular filtration} + \text{Tubular secretion} - \text{Tubular reabsorption}$. However, based on the provided equation structure, the missing term is the initial filtrate formed at the glomerulus.
$(b)$ Dialysis fluid is designed to mimic the composition of blood plasma but lacks nitrogenous waste products (like urea, uric acid, and creatinine) so that these substances can diffuse out of the patient's blood into the dialysis fluid.

(N/A) Micturition: The process of release of urine is called micturition. The urinary bladder stores urine until a voluntary signal is given by the $CNS$ (Central Nervous System). As the bladder fills,stretch receptors on its walls send signals to the $CNS$. The $CNS$ then sends motor messages to initiate the contraction of the smooth muscles of the bladder and the simultaneous relaxation of the urethral sphincter,causing the release of urine.
Disorders of the Excretory System:
$1$. Uremia: Presence of excessive urea in the blood,often caused by kidney malfunction or infection in the uriniferous tubules.
$2$. Renal Failure: Malfunctioning of the kidneys leading to the inability to excrete waste properly. It can be treated by hemodialysis,where an artificial kidney (haemodialyzer) filters the blood using a cellophane membrane and a dialyzing fluid.
$3$. Kidney Stones: Insoluble masses of crystallized salts (like oxalates) formed within the kidney,which can obstruct the urinary tract and cause acute pain.
$4$. Nephritis: Inflammation of the renal pelvis,interstitial tissues,and calyces,typically caused by bacterial infection. Symptoms include a burning sensation during urination,back pain,and increased frequency of urination.

(A) $(1)$ The Glomerular Filtration Rate $(GFR)$ in a healthy individual is approximately $125 \text{ mL/min}$ or $180 \text{ L/day}$.
$(2)$ Sebaceous glands are exocrine glands in the skin that secrete an oily or waxy matter called sebum to lubricate and waterproof the skin and hair.

(C) Tubular secretion is a process where substances like $H^+$,$K^+$,and ammonia are secreted into the filtrate. This process occurs in both the proximal convoluted tubule $(PCT)$ and the distal convoluted tubule $(DCT)$,as well as the collecting duct. Therefore,the statement that tubular secretion takes place in the $PCT$ only is incorrect.

(D) The $pH$ of human urine typically ranges from $5.0$ to $7.8$.
The average $pH$ value is approximately $6.0$,which indicates that urine is slightly acidic in nature.

(C) $I.$ False: Urine is hypotonic when entering the distal convoluted tubule $(DCT)$ because the ascending limb of the loop of Henle is impermeable to water but permeable to electrolytes,leading to dilution of the filtrate.
$II.$ True: As urine moves through the collecting duct,water is reabsorbed due to the hypertonic medullary interstitium,making the urine hypertonic.
$III.$ True: In the proximal convoluted tubule $(PCT)$,the filtrate remains isotonic to the blood plasma because water and solutes are reabsorbed in equal proportions.
$IV.$ False: Urine becomes more and more hypertonic as it passes through the descending limb of the loop of Henle because water is reabsorbed into the hypertonic medullary interstitium.

(D) Statement $I$ is false because the blood vessel leading to the glomerulus is the afferent arteriole,while the efferent arteriole carries blood away from it.
Statement $II$ is true as all these structures are part of the renal circulatory system and contain blood.
Statement $III$ is true because cortical nephrons have a short Henle's loop and the vasa-recta is either highly reduced or absent.
Statement $IV$ is true because in juxta-medullary nephrons,the vasa-recta forms a capillary network that runs parallel to the Henle's loop.
Therefore,statements $II, III,$ and $IV$ are true.

(C) The nephron is the functional unit of the kidney responsible for urine formation,which involves three main processes: glomerular filtration,tubular reabsorption,and tubular secretion.
Urea synthesis does not occur in the nephron; instead,it takes place in the hepatocytes (liver cells) through the Ornithine cycle (also known as the Urea cycle).

(D) The kidneys filter approximately $1100-1200 \; ml$ of blood per minute.
This volume represents roughly $1/5^{th}$ of the total cardiac output,which is the amount of blood pumped out by each ventricle of the heart in a minute (approximately $5000 \; ml$ per minute).

(A) The kangaroo rat is a desert-dwelling rodent that exhibits specific physiological adaptations to survive without drinking liquid water.
$1$. Nasal countercurrent mechanism: This helps in conserving water by cooling the exhaled air,which causes water vapor to condense in the nasal passages.
$2$. Dependence on metabolic water: The kangaroo rat produces water as a byproduct of the oxidation of fats and carbohydrates during cellular respiration.
$3$. Highly hypertonic urine: Its kidneys are highly efficient at concentrating urine,which minimizes water loss during excretion.
Therefore,mechanisms $A, B,$ and $C$ are correct adaptations for water conservation.

(A) During pregnancy,the glomerular filtration rate $(GFR)$ increases significantly due to physiological changes in the body.
Because of this increased $GFR$,the amount of glucose filtered into the renal tubules (tubular load) increases.
When this load exceeds the renal threshold (tubular maximum) for glucose reabsorption,the excess glucose cannot be reabsorbed and is excreted in the urine,a condition known as glycosuria.
Therefore,both the Assertion and the Reason are correct,and the Reason provides the correct explanation for the Assertion.

(B) Assertion is correct: Birds possess advanced metanephric kidneys. The absence of a urinary bladder is a significant flight adaptation to reduce body weight.
Reason is correct: The South American Ostrich $(Rhea \ \text{americana})$ is a flightless bird and is an exception among birds as it possesses a urinary bladder.
Conclusion: Both Assertion and Reason are true,but the Reason does not explain why birds generally lack a urinary bladder.

(B) In the proximal convoluted tubule $(PCT)$,reabsorption of $HCO_3^-$,$NaCl$,and $H_2O$ occurs,while $H^+$ and $NH_3$ are secreted into the filtrate to maintain $pH$ and ionic balance.
In the distal convoluted tubule $(DCT)$,conditional reabsorption of $Na^+$ and $H_2O$ occurs,and there is selective secretion of $H^+$ and $K^+$ ions and $NH_3$ to maintain $pH$ and sodium-potassium balance in the blood.
Comparing the options,Diagram $B$ correctly represents the reabsorption and secretion processes in both the proximal $(P)$ and distal $(D)$ tubules as per standard physiological models.

(D) According to $NCERT$,on average,$1100-1200 \text{ ml}$ of blood is filtered by the kidneys per minute.
This volume constitutes roughly $1/5^{\text{th}}$ of the blood pumped out by each ventricle of the heart in a minute.
$125 \text{ ml/minute}$ is the Glomerular Filtration Rate $(GFR)$,which is the volume of filtrate formed per minute,not the total volume of blood filtered by the kidneys.
Therefore,both options $B$ and $C$ are correct,making $D$ the right choice.

(C) Urea enters the nephron through two primary mechanisms:
$1$. $iii$. Ultrafiltration: During the process of glomerular filtration,urea is filtered along with water and other solutes into the Bowman's capsule (urinary space).
$2$. $iv$. Inner medullary segment of collecting tubule: Urea is reabsorbed from the collecting duct into the medullary interstitium to maintain the osmolarity gradient. However,it also diffuses back into the thin ascending limb of the loop of Henle and the inner medullary collecting duct to maintain this cycle. Among the given choices,the entry of urea into the nephron occurs via ultrafiltration $(iii)$ and back-diffusion into the inner medullary collecting tubule $(iv)$ or thin ascending limb. Based on standard physiological models,the correct combination is $iii$ and $iv$. Since the provided options are limited,we identify the most accurate physiological pathways. Given the options,$iii$ and $iv$ represent the entry points for urea recycling and filtration.