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Class 10 SELINA Solutions Biology Chapter 9 - The Excretory System

The Excretory System Exercise Ex. 1

Solution A.1

(c) Excretion

Solution A.2

(b) Uterus

Solution A.3

(d) Nephron

Solution A.4

(c) Urine 

Solution A.5

(c) Renal pelvis  

Solution A.6

(b) Liver 

Solution A.7

(c) Urea

Solution A.8

(d) Glycosuria

Solution A.9

(c) Uremia

Solution A.10

(d) DCT

Solution B.1

(a) Cortex

(b) Glomerulus

(c) Distal convoluted tubule (DCT)

(d) Kidney

(e) Urethra

(f) Urochrome

Solution B.2

(a) Afferent arteriole, glomerulus, efferent arteriole, capillary network, renal vein

(b) Renal artery, kidney, ureter, urinary bladder, urethra

Solution B.3

(a) The outer darker portion of the kidney is termed as cortex.

(b) The Bowman's capsule and the glomerulus together are called as Malpighian capsule or renal capsule.

(c) A pair of renal arteries branch off from the dorsal aorta and enter the kidney.

(d) The glomerular filtrate is collected in Bowman's capsule after the process of ultrafiltration.

(e) The pigment bilirubin is the breakdown product of the hemoglobin of dead RBCs.

Solution B.4

Abnormal constituents


(a) Blood


(b) Glucose


(c) Albumin


(d) Bile pigments

Anaemia, hepatitis (jaundice), liver cirrhosis


Solution C.1

(a) Glomerulus is involved in the process of ultrafiltration.The liquid part of the blood which is plasma including urea, salts, glucose filters out from the glomerulus into the renal tubule.

(b) Henle's loop is involved in reabsorption of water and sodium ions.

(c) Ureter carries urine to the urinary bladder by ureteral peristalsis.

(d) Renal artery supplied blood to the kidney.

(e) Urethra is involved in the process of micturition i.e. expelling urine out of the body.

Solution C.2

Column I

Column II 

(a)   Bowman's Capsule


(b)   Contains more CO2 and less urea

Renal Vein

(c)    Anti-diuretic hormone

Regulates amount of water excreted

(d)   Contains more urea

Renal artery

Solution C.3

In a nephron, the blood flows through the glomerulus under great pressure. The reason for this great pressure is that the efferent (outgoing) arteriole is narrower than the afferent arteriole (incoming). This high pressure causes the liquid part of the blood to filter out from the glomerulus into the renal capsule.

Solution C.4

(a) Three nitrogenous wastes of our body:

1. Urea

2. Uric acid

3. Ammonia

(b) Three organic wastes of our body:

1. Urea

2. Uric acid

3. Creatinine

(c) Three inorganic wastes of our body:

1. Common salt (NaCl)

2. Iron

3. Calcium

(d) Three main parts of our urinary system:

1. Kidney

2. Urinary bladder

3. Ureter

(e) Six main parts of nephron:

1. Bowman's capsule

2. Glomerulus

3. Renal capsule

4. Proximal convoluted tubule (PCT)

5. Loop of Henle

6. Distal convoluted tubule (DCT)

(f) Three stages of urine formation:

1. Ultrafiltration

2. Reabsorption

3. Tubular secretion

(g) Three types of fluids in different parts of a nephron:

1. Glomerular filtrate

2. Glomerular filtrate with glucose and sodium

3. Urine

Solution C.5

(a) Odd term: Neuron, Category: Others are parts of the human excretory system.

(b) Odd term: Excess sodium chloride, Category: Others are organic nitrogenous wastes.

(c) Odd term: Loop of Henle, Category: Others are parts of the internal structure of kidney.

(d) Odd term: Papilla, Category: Others are parts of the kidney tubule or nephron.

Solution C.6

(a) PCT: Proximal Convoluted Tubule

(b) DCT: Distal Convoluted Tubule

(c) ADH: Antidiuretic hormone

(d) ORS: Oral Rehydration Solution

Solution C.7

(a) Kidney: It is located on either side of the backbone and protected by the last two ribs.


(b) Uriniferous tubule: Uriniferous tubule begins in the cortex; the tubule dips down to the medulla, then return to the cortex before draining into the collecting duct.


(c) Malpighian capsule: It comprises of Bowman's capsule and glomerulus and is located in the kidney tubule.


(d) Loop of Henle: It runs in the medulla to turn back and to re-enter the cortex to continue into the next convoluted region of the tubule.

Solution D.1

(a) Excretion: The process of removal of chemical wastes especially nitrogenous waste from the body is known as excretion.


(b) Kidney: Kidneys are primary excretory organs eliminating nitrogenous wastes mainly urea from the blood and throwing it out of the body in the form of urine.


(c) Micturition: The process of expelling urine out of the body through urethra by opening the sphincter muscles passing of urine involving relaxation of sphincter muscles between the urinary bladder and urethra is called micturition.


(d) Osmoregulation: Osmoregulation is a process of maintaining the blood composition of the body i.e. the normal osmotic concentration of water and salts in the body.

Solution D.2

(a) Differences between Ureter and Urethra (function):



Acts as a passage for the transfer of urine from the kidneys to the urinary bladder

Connects the bladder to the body's exterior, allowing urine to exit the body.


(b) Differences between Diabetes mellitus and diabetes insipidus (hormones involved):

Diabetes mellitus

Diabetes insipidus

Deficiency of insulin causes diabetes mellitus.

Deficiency of antidiuretic hormone (ADH) causes diabetes mellitus.


(c) Differences between Glycosuria and Albuminuria (abnormal constituents):



Excess glucose passes with urine in glycosuria.

Albumin proteins pass out via urine in albuminuria.


(d) Differences between Diuresis and Uremia (problem):



Increased production of urine causes diuresis.

Accumulation of urea in the blood causes uremia.


(e) Differences between Malpighian capsule and Loop of Henle (location):

Malpighian capsule

Loop of Henle

It is located in the cortex of the kidney.

It is present in the medulla of the kidney.


Solution D.3

(a) Excretion aids in the removal of hazardous nitrogenous wastes from our bodies and plays a crucial role in osmoregulation, or the maintenance of physiological homeostasis. Hence, excretion is a necessary process of our body.

(b) Both the Bowman's capsule and the proximal convoluted tubule lie in the cortex of the kidney tubule. As a result, the cortex of the kidneys shows a 'dotted' appearance.

(c) In summer, we lose a considerable part of the water through perspiration. As a result, the kidneys have to reabsorb more water from the glomerular filtrate making the urine concentrated. Thus, we urinate fewer times in summer than in winter and the urine passed is generally thicker.

(d) Henle's loop and collecting ducts lie in the medulla. As a result, the medulla of kidneys shows a 'striped' appearance.

Solution E.1

(a) Hilum is found between medulla and pelvis

(b) Nephron is the basic structural and functional unit of kidney.

(c) Kidneys are primary excretory organs that eliminate nitrogenous wastes such as urea from the blood in the form of urine.

(d) The kidneys are located on either side of the backbone, below the rib cage.

(e) Renal artery (A) carries deoxygenated (impure) blood and renal vein (B) carries oxygenated (pure) blood.

(f) The renal pelvis is a large cavity that collects the urine as it is produced.

(g) Osmoregulation is the process by which an organism adjusts the water and salt balance in its body and maintains homeostasis.

(h) Dialysis is an artificial process which is normally suggested by the doctors to the patients in case of a permanent damage to both the kidneys. It helps in the removal of waste products and excess fluids from the body, when the kidneys are not functioning properly.

(i) The posterior pituitary gland secretes ADH (antidiuretic hormone). It acts on nephrons and aids in the reabsorption of water from the kidney tubules.

(j) Malpighian capsule


Solution E.2

(a) Excretory system and Circulatory system.

(b) 1-kidney, 2-renal artery, 3-ureter, 4-urinary bladder, 5-urethera

(c) Nephron

(d) Urea and ammonia

(e) Ultrafiltration and selective reabsorption

Solution E.3

(a) 5 - Glomerulus

(b) 5 (Glomerulus) and 3 (Bowman's capsule) combination- Malpighian capsule/Renal capsule

(c) 3 - Bowman's capsule

(d) 2 - Proximal Convoluted Tubule

(e) 7 - Collecting duct

(f) 1 - Loop of Henle

(g) 6 - Distal Convoluted Tubule

(h) The efferent arteriole is narrower than the afferent arteriole. As a result, blood flows through the glomerulus under great pressure. This generates very high pressure called hydrostatic pressure which causes the liquid part of the blood to filter out from the glomerulus into the renal tubule.

(i) 5 - Glomerulus

(j) Urea and sodium chloride are two important constituents of urine.

Solution E.4

(a) The process of removal of chemical wastes especially nitrogenous waste from the body is known as excretion.


(b) As the cortex region contains numerous nephrons or kidney tubules, therefore, it shows a dotted appearance.


(c) As the medulla region contains several conical pyramids, therefore, it shows a striped appearance.


(d) The blood vessel 'B' is renal artery and the blood vessel 'A' is renal vein. So the blood vessel 'B' contains oxygenated blood with high concentration of urea and glucose whereas the blood vessel 'A' contains deoxygenated blood with low concentration of urea and glucose as compared to renal artery.

Solution E.5

a. The structure is a Bowman's capsule, which is part of the nephron. The Bowman's capsule is found in the cortex of the kidney.


1 - Afferent arteriole 

2 - Glomerulus

3 - Bowman's capsule

4 - Efferent arteriole


c. Urine formation occurs in two steps - ultrafiltration and reabsorption.


d. The process occurring in 2 and 3 is known as ultrafiltration.

In the glomerulus, the blood flows under high pressure because of the narrow lumen of the capillary network of the glomerulus. This forces most of the components (both waste and useable materials) of the blood out of the capillaries. This process of the filtration of blood under high pressure in the Bowman's capsule is known as ultrafiltration.

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