07: The Excretory System : Icse-x-biology

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ICSE-X-Biology

07: The Excretory System

with Solutions - page 3

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Qstn #3
What is a uriniferous tubule? How does it function?
Ans : A uriniferous tubule also known as the kidney tubule is the structural and functional unit of the kidney.
It takes in impure blood from the renal artery and removes wastes in the form of urine. It also provides a larger surface area for reabsorption of salts and water.

Qstn #4
Why is it necessary to maintain a normal osmotic concentration of the blood?
Ans : Maintaining a normal osmotic concentration in the body means regulating the percentage of water and salts. If this regulation mechanism fails we either end up losing vital salts and water or may accumulate unwanted salts and excess water in our body.

Qstn #5
If you donate one kidney to a needy patient, would it cause any harm to you? Give reason.
Ans : If one kidney is donated to a needy patient, the other kidney alone is sufficient for removing wastes or excretion. Thus, the donor can live a normal life.

Qstn #6
In summer the urine is slightly thicker than in winter explain the reason.
Ans : During summer, a considerable part of water is lost through perspiration so the kidneys have to reabsorb more water from the urine. This makes the urine thicker in summer than in winters.

Qstn #7
Differentiate between the following pairs of terms:

#7-a
Bowman's capsule and malpighian capsule.
Ans : Bowman's capsule is a thin walled cup containing the glomerulus. This Bowman's capsule along with the glomerulus is known as malpighian capsule.

#7-b
Renal cortex and renal medulla
Ans : The renal cortex is the outer darker region of the kidney whereas the renal medulla is the
inner lighter region of the kidney.

#7-c
Renal pelvis and renal papilla
Ans : Renal pelvis is the expanded front end of the ureter in the kidney whereas the renal papilla is the apex of the renal pyramid which projects into the pelvis.

#7-d
Urea and urine
Ans : Urea is the chief excretory product which is excreted in the form of urine whereas urine is
the filtrate left after reabsorption and tubular secretion which contains 95% water and 5% solid wastes.

#7-e
Excretion and katabolism
Ans : Excretion is the process of removal of chemical wastes especially nitrogenous wastes from the body. Catabolism on the other hand is the set of metabolic pathways which break down molecules into smaller units and release energy.

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

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

Column I Column II

Ans :
Column I

Column II

#9-a
Bowman's Capsule

Renal artery

Ans : Bowman's Capsule

Glomerulus

#9-b
Contains more CO₂ and less urea

Regulates amount of water excreted

Ans : Contains more CO₂ and less urea

Renal Vein

#9-c
Anti-diuretic hormone

Renal Vein

Ans : Anti-diuretic hormone

Regulates amount of water excreted