Frank Solutions for Chapter 8 Excretory System Class 10 Biology ICSE

Excretory System


1. What is excretion? Give names of excretory organs.
Answer
Separation and elimination of the metabolic nitrogenous wastes from the body is called excretion.
Kidneys, skin and lungs are important excretory organs.

2. Give names of common excretory products in humans.
Answer
Carbon dioxide (CO2) and urine

3. Why the conversion of ammonia to urea is essential in human body?
Answer
Ammonia is toxic in even small amounts and therefore it must be removed from the body. The urea cycle or the ornithine cycle, in the liver, involves the conversion of ammonia into urea. Then the urea is then transported to the kidneys where it is excreted.

4. What is the function of a nephron?
Answer
Nephron is the basic structural and functional unit of the kidney.
Its chief function is to regulate the concentration of water and soluble substances like sodium salts by filtering the blood, reabsorbing what is needed and excreting the rest as urine.

5. Label the diagram given below:
Answer

6. What is dialysis?
Answer
Dialysis is a process of separation of toxic substances from the blood stream through a membrane by kidney machine or artificial kidney.

7. Name the following:

(i) Animals which excrete ammonia.
(ii) Animals which eliminate urea.
(iii) Animals which excrete uric acid.
(iv) Organ which produces urea.
(v) Functional unit of kidney.
(vi) Organ which stores urine.
(vii) Organ where ultrafiltration occurs.

Answer
(i) Ammonotelic
(ii) Ureotelic
(iii) Uricotelic
(iv) Liver
(v) Nephron
(vi) Urinary Bladder
(vii) Glomerulus

8. Choose the odd one out in the following series:

(i) Proximal convoluted duct, loop of Henle, vein.
(ii) Kidney, ureter, heart
(iii) Urea, uric acid, hemoglobin.
(iv) Glomerulus, alveoli, bronchi.
(v) Renal fat, renal capsule, nerve.
(vi) Column of Bertini, minora calyces, brain.

Answer
(i) Vein
(ii) Heart
(iii) Hemoglobin
(iv) Glomerulus
(v) Nerve
(vi) Brain

9. Given below is a diagram of a human kidney, cut open longitudinally. Answer the following.
(i) Give definition of excretion.
(ii) Name the unit of kidney.
(iii) Why does the cortex of kidney show dotted appearance?
(iv) List the functions of the kidney.
Answer
(i) Separation and elimination of the metabolic nitrogenous wastes from the body is called excretion.
(ii) Nephron.
(iii) The cortex of kidney shows dotted appearance because it contains numerous complex structures called nephrons.
(iv) Formation of urine and osmoregulation are important functions of kidney.

10. Choose the correct answer:

(i) Composition of extracellular fluid is regulated by
(a) kidney
(b) brain
(c) lungs
(d) thyroid
Answer
(a) kidney

(ii) Uric acid is excreted by
(a) pigeon
(b) frog
(c) rabbit
(d) man
Answer
(a) pigeon

(iii) Presence of RBCs in urine is called
(a) pyuria
(b) glycosuria
(c) haematuria
(d) albuminuria
Answer
(c) haematuria

(iv) A condition of failure of kidney to form urea is called
(a) creatine
(b) hematuria
(c) keturia
(d) anuria
Answer
(d) anuria

(v) What happens if one kidney is removed from the body of human being?
(a) Death due to poisoning
(b) Uraemia and death
(c) Stoppage of urination
(d) Nothing will happen
Answer
(d) Nothing will happen

(vi) Orinithin cycle operates in
(a) liver
(b) stomach
(c) pancreas
(d) oral cavity
Answer
(a) liver

(vii) Physiologically urea is produced by the action of an enzyme
(a) uricose
(b) urease
(c) arginase
(d) none
Answer
(b) urease

(viii) Vitamin excreted through urine in mammals is
(a) vitamin A
(b) vitamin C
(c) vitamin D
(d) vitamin K
Answer
(b) vitamin C

(ix) Excess proteins are converted into urea in
(a) lungs
(b) liver
(c) kidneys
(d) intestine
Answer
(b) liver

(x) The smallest functional unit of the kidney is
(a) glomerulus
(b) Bowman's capsule
(c) nephron
(d) collecting tubule
Answer
(c) nephron

(xi) Narrow apex of pyramid in kidney is called
(a) pelvis
(b) renal papilla
(c) column of Bertini
(d) duct of Bellini
Answer
(b) renal papilla
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