Selina ICSE Class 10 Biology Solutions Chapter 7 The Excretory System Elimination Of Body Wastes

Selina ICSE Solutions

Multiple Choice Type: 
(Select the most appropriate option in each case)

Question 1: Excretion primarily involves
(a) removal of all by products during catabolism
(b) removal by products during anabolism
(c) removal of nitrogenous wastes
(d) throwing out excess water

Solution :

Removal of nitrogenous wastes.

Question 2: Maximum amount of water from the glomerular filtrate is reabsorbed in
(a) proximal convoluted tubule
(b) descending limbs of loop of Henle
(c) ascending limb of loop of Henle
(d) distal convoluted tubule

Solution :

Proximal convoluted tubule

Question 3: Which one of the following in real sense is NOT an excretory activity?
(a) giving out carbon dioxide
(b) passing out faecal matter
(c) sweating
(d) Removal of urea

Solution :


Question 4: In humans, urea is formed in
(a) ureter
(b) liver
(c) spleen
(d) (d) Kidney

Solution :


Very Short Answer Type Questions:

Question 1: Name the following:
(a) The organ which produces urea
(b) The outer region of kidney containing the Bowman’s capsule
(c) The tuft of capillaries inside the Bowman’s capsule
(d) The part of kidney tubules where the term urine is first used for the fluid in it
(e) The vein in which urea concentration is maximum
Solution 1:
(a) Liver
(b) Cortex
(c) Glomerulus
(d) Collecting duct
Renal artery (The renal vein contains urea; however the renal artery contains a larger concentration of urea than the renal vein.).

Question 2: Given below are two sets (a and b) of five terms each. Rewrite the terms in their correct order so as to be in logical sequence.
(a) Afferent arteriole, renal vein, capillary network, glomerulus, efferent arteriole.
(b) Renal artery, urethra, ureter, kidney, urinary bladder.
Solution 2:
(a) Afferent arteriole, glomerulus, efferent arteriole, capillary network, renal vein
(b) Renal artery, kidney, ureter, urinary bladder, urethra

Question 3: In each one of the following sets of body parts or substances or processed, pick out the one item which overall includes the remaining foir.
(a) Glomerular filtrate, bowman’s capsule, ultrafiltration, glomerulus, blood plasma.
(b) skin, liver, lungs, kidney, excretion
(c) ADH, Water, pituitary, osmoregulation, urine
(d) CO2, bile pigments, water, excretion, urea.
Solution 3:
(a) Ultrafiltration
(b) Excretion
(c) Osmoregulation
(d) Excretion

Short Answer Type Questions:

Question1: Write down the functional activity of the following parts,
(a) Glomerulus …………………
(b) Henle’s loop ………………
(c) Ureter ………………………
(d) Renal artery ………………
(e) Urethra ……………………
Solution 1:
(a) Glomerulus is engaged in the ultrafiltration process. The plasma, which contains urea, ions, and glucose, is filtered out of the glomerulus and into the renal tubule.
(b) Henle’s loop is involved in water and sodium ion reabsorption.
(c) Ureteral peristalsis transports urine from the ureter to the urinary bladder.
(d) The kidney was supplied with blood via the renal artery.
(e) The urethra is engaged in micturition, or the process of excreting pee from the body.

Question 2: Why is excretion necessary? Name the common excretory substance in our body.
Solution 2:
Excretion aids in the removal of hazardous wastes from our bodies and also aids in osmoregulation, or the body’s preservation of homeostasis.
Excretory products include carbon dioxide, water, nitrogenous substances like urea and uric acid, and excess salts.

Question 3: What is a uriniferous tubule? How does it function?
Solution 3:
The structural and functional unit of the kidney is the uriniferous tubule, commonly known as the kidney tubule. It receives impure blood from the renal artery and excretes wastes as urine. It also gives a wider surface area for salt and water reabsorption.

Question 4: Why is it necessary to maintain a normal osmotic concentration of the blood?
Solution 4:
The percentage of water and salts in the body must be regulated in order to maintain a proper osmotic concentration. If this mechanism fails, we may lose important salts and water, or we may collect undesired salts and excess water in our bodies.

Question 5: If you donate one kidney to a needy patient, would it cause any harm to you? Give reason.
Solution 5:
If one kidney is donated to a patient in need, the other kidney is sufficient for waste removal and excretion. As a result, the donor is able to live a regular life.

Question 6: In summer the urine is slightly thicker than in winter explain the reason.
Solution 6:
Because a significant amount of water is lost through perspiration during the summer, the kidneys must reabsorb more water from the urine. In the summer, the urine is thicker than in the winter.

Question 7: Differentiate between the following pairs of terms:
(a) Bowman’s capsule and malpighian capsule.
(b) Renal cortex and renal medulla
(c) Renal pelvis and renal papilla
(d) Urea and urine
(e) Excretion and catabolism
Solution 7:
(a) Bowman’s capsule is a cup with a thin wall that contains the glomerulus. Malpighian capsule refers to the Bowman’s capsule as well as the glomerulus.
(b) The renal cortex is the kidney’s outer darker region, whereas the renal medulla is the kidney’s interior lighter region.
(c) The renal papilla is the top of the renal pyramid that expands into the pelvis, whereas the renal pelvis is the extended front end of the ureter in the kidney.
(d) Urea is the primary excretory product expelled in the form of urine, whereas urine is the filtrate remaining after reabsorption and tubular secretion, including 95% water and 5% solid wastes.
(e) Excretion is the process of removing chemical wastes from the body, particularly nitrogenous wastes.
(f) On the other hand, catabolism refers to a series of metabolic mechanisms that break down molecules into smaller units and release energy.

Question 8: Name the main nitrogenous metabolic waste excreted out by mammals including humans.
Solution 8:
Urea, creatinine, uric acid

Question 9: Match the terms in Column I with those in Column II and write down the matching pairs.

Column IColumn II
Bowman’s CapsuleRenal artery
Contains more CO2 and less ureaRegulates amount of water excreted
Anti-diuretic hormoneRenal Vein
Contains more ureaGlomerulus

Solution 9:

Column IColumn II
Bowman’s Capsule(d) Glomerulus
Contains more CO2 and less urea(c) Renal Vein
Anti-diuretic hormone(b) Regulates amount of water excreted
Contains more urea(a) Renal artery

Question 10: In a nephron, the ………….. flows through the under great pressure. The reason for
this great pressure is that the ………….. (outgoing) ………….. is narrower than the …………..
(incoming). This high pressure causes the………….. part of the blood to filter out from the into the renal capsule.
Solution 10:
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.

Long Answer Type Questions:

Question 1: Define the following terms:
a) Ultrafiltration
b) Micturition
c) Renal pelvis
d) Urea
e) Osmoregulation
Solution 1:
(a) Ultrafiltration – The filtration of blood in the glomerulus at high pressure, during which the liquid portion of the blood, plasma, as well as urea, glucose, amino acids, and other compounds, enters the renal tubule.
(b) Micturition – The process of transferring urine via the urethra by opening the sphincter muscles between the urinary bladder and the urethra and relaxing the sphincter muscles between the urinary bladder and the urethra.
(c) Renal pelvis – The extended front end of the ureters into the kidney is known as the renal pelvis.
(d) Urea – A nitrogenous waste produced predominantly in the liver as dead protein remains and excess amino acids are broken down.
Osmoregulation – It is a process that keeps the body’s blood composition, or the normal osmotic concentration of water and salts, in check.

Question 2: Explain the terms ultrafiltration and selective absorption
Solution 2:
The glomerulus filters the blood, which is referred to as ultrafiltration. Under high pressure, blood containing urea from the afferent arteriole enters the glomerulus. Because the efferent arteriole is narrower than the afferent arteriole, a high pressure is formed. The liquid fraction of the blood filters out of the glomerulus and into the renal tubule due to the high pressure. The glomerular filtrate is the name for this type of filtrate.
Water, urea, salts, glucose, and other plasma solutes make up glomerular filtrate. The glomerulus retains blood corpuscles, proteins, and other big molecules. As a result, the blood that the efferent arteriole transports is quite thick.
Selective absorption
The glomerular filtrate that enters the renal tubule contains many components that can be used, such as glucose and salt. A lot of water, along with these useful components, is reabsorbed when this filtrate goes through the renal tubule. ‘Selective absorption’ is the term for this type of reabsorption. Reabsorption takes place only to the extent that the blood’s regular concentration is not disrupted.

Question 3: What is dialysis? Under what condition is it carried out?
Solution 3:
Dialysis is the process of using an artificial kidney or a dialysis machine to remove waste from the body. Excess salts and urea are removed from the patient’s blood as it passes through the machine via the radial artery. The blood is then cleaned and reintroduced to a vein in the same arm.
In the event that both kidneys fail, dialysis is used. If there is lasting damage, the dialysis must be done twice a week for around 12 hours.

Structured / Application/ Skill Type Questions:

Question 1: Look at the figure given bellow, it is a section of human kidney as seen from the front.

(a) Is it the left kidney or the right one? Give reason in support of your answer.
(b) Is it a longitudinal section or a cross-section?
(c) Name the parts numbered 1-5
(d) which area/part (give its name and the number given on the diagram) contains the following respectively:
(i) malpighian capsule
(ii) The pyramids
(iii) Freshly collected urine
Solution 1:
(a) The image displayed could be of the left or right kidney. Because the right kidney is slightly lower than the left, we’ll need photos of both kidneys to compare them.
(b) It is a slice of the kidney taken longitudinally.
(c) 1-renal artery, 2-renal vein, 3-ureter, 4-cortex, 5-pelvis
(i) 4/cortex
(ii) Medulla
(iii) 5/pelvis

Question 2: Given alongside is the figure of certain organs and associated parts in the human body. Study the same and answer the questions that follow:
(a) Name all the organ systems shown completely or even partially
(b) name the parts numbered 1 to 5
(c) Name the structural and functional unit of the part marked ‘1’
(d) name the two main organic constituents of the fluid that flows down the part labelled ‘3’
(e) Name the two major steps involved in the formation of the fluid that passes down the part labelled ‘3’

Solution 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

Question 3: The following diagram represents a mammalian kidney tubule (nephron) and its blood supply.

Parts indicated by the guidelines 1 to 8 are as follows:
1. Afferent arteriole from renal artery
2. efferent arteriole
3. Bowman’s capsule
4. Glomerulus;
5. Proximal convoluted tubule with blood capillaries;
6. Distal convoluted tubule with blood capillaries;
7. collecting tubule;
8. U-shaped loop of Henle
Study the diagram and answer the question that follow:
(a) where does ultrafiltration take place?
(b) Which structure contains the lowest concentration of urea?
(c) Which structure contains the highest concentration of urea?
(d) Which structure (normally) contains the lowest concentration of glucose?
(e) where is most water reabsorbed?
Solution 3:
(a) 4/Glomerulus
(b) 2/Efferent arteriole
(c) 1/ Afferent arteriole from renal artery
(d) 7/Collecting tubule
(e) 5/ Proximal convoluted tubule with blood capillaries

Question 4: Given alongside is a highly simplified (but also somewhat wrong) diagram of the human kidney cut open longitudinally. Answer the questions that follow.
a) Define excretion
b) Name the functional units of the kidneys.
c) Why does the cortex of the kidney show a dotted appearance?
d) Mention two functions of the kidney.
Write two differences in the composition of the blood flowing through the blood vessels, ‘A’ and ‘B’[There is an error in the diagram. Can you identify it?]

Solution 4:
(a) Excretion is the process of removing chemical wastes from the body, particularly nitrogenous waste.
(b) Nephrons
(c) The cortical region has a dotted look because it contains many nephrons or kidney tubules.
(d) Kidneys aid in waste removal, excretion, and osmoregulation.
(e) The renal artery is the blood vessel ‘B,’ while the renal vein is the blood vessel ‘A.’
In comparison to the renal artery, the blood vessel ‘B’ includes oxygenated blood with high urea and glucose concentrations, whereas the blood vessel ‘A’ contains deoxygenated blood with low urea and glucose concentrations.

Question 5: Study the diagram given alongside and then answer the questions that follow:
(a) Name the region in the kidney where the above structure is present?
(b) Name the parts labelled 1, 2, 3 and 4.
(c) Name the stages involved in the formation of urine
(d) What is the technical term given to the process occurring in 2 and 3? Briefly describe the process.

Solution 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.
(b) 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.

Selina ICSE Class 10 Biology Solutions Chapter 7 The Excretory System ...