Respiration and Elimination of Nitrogenous Wastes : 12th Class Biology Q Ans Lesson 14 – NIOS

Respiration and Elimination of Nitrogenous Wastes : 12th Class Biology Q Ans Lesson 14 – NIOS

Respiration and Elimination of Nitrogenous Wastes : 12th Class Biology Q Ans Lesson 14 - NIOS


  1. Define respiration
    Ans. Stepwise oxidation of glucose resulting in release of energy.
  2. Name the two gases that are exchanged during respiration.
    Ans. O2, CO2
  3. What is cutaneous respiration? Name one animal that undertakes cutaneous respiration.
    Ans. Respiration by the skin; frog
  4. What is the colour of the blood of the earthworm? Name the pigment responsible for the colour.
    Ans. Red, haemoglobin
  5. How is oxygen transported to the cells in the cockroach?
    Ans. Directly through tracheoles
  6. Name the group of animals in which blood is not involved in gaseous exchange. – Insects
  7. How does trachea communicate with the exterior in cockroach?
    Ans. Through spiracles
  8. Trace the path of air from the nostrils to the lungs in the human body.
    Ans. Nostrils → pharynx → bronchi → bronchioles → lungs
  9. Name the part of the respiratory system where air is filtered, moistened and warmed in humans
    Ans. Nasal cavity
  10. What is the function of the epiglottis in humans?
    Ans. Prevent food from entering the trachea or food pipe


  1. What is breathing?
    Ans. mechanism of taking in air and then giving it out
  2. What is the position of the diaphragm at the time of expiration?
    Ans. relaxed and dome shaped
  3. What is the capacity of tidal volume? – 500 mL
  4. What is the maximum number of oxygen molecules with which haemoglobin can Plants and animals combine? – 4 molecules
  5. Name the blood vessel that takes oxygenated blood from the lungs to the heart. – Pulmonary vein
  6. What are the three forms in which carbon dioxide is transported by the blood?
    Ans. (a) dissolved in plasma as carbon dioxide – 5%
    (b) as carboxy carbamino haemoglobin in RBC – 20%
    (c) as bicarbonate ions in RBC or plasma – 75%

  7. Name the vaccine used for prevention of TB.
    Ans. Bacillus Calmette Guerin (BCG)
  8. What is an occupational hazard.
    Ans. Silicosis or asbestosis
  9. What is the difference between bronchitis and asthma?
    Ans. Bronchitis is an infection of the bronchi and antibiotics can cure it whereas bronchial asthma is an allergic reaction.
  10. The alveoli of a heavy smoker were damaged, their surface area was reduced and elasticity was lost. What is the technical term for this condition.
    Ans. Emphysema


  1. Name the organ where urea is produced and the organ from where urea is excreted. – Liver, Kidney
  2. Which is the most toxic form of nitrogenous waste? Name an organism that excretes it.
    Ans. Ammonia; amoeba and fresh water fishes


  1. In what form the cockroaches excrete their nitrogenous waste? What is its advantage for cockroach?
    Ans. Uric acid; this is to prevent water loss as these animals need to conserve water
  2. Where do Malpighian tubules of cockroach open?
    Ans. Malpighian tubules open at the junction of mid and hind gut
  3. List the parts of human excretory system and their functions.
    Ans. Kidney – filters nitrogenous wastes, excess of water and salt
    Ureters – transport urine to the bladder
    Urinary bladder – temporary storage of urine
    Urethra – drains urine outside the body
  4. Name the functional unit of kidney and its parts.
    Ans. Nephron, consisting of renal corpuscles made up of Bowman’s capsules and glomerulus, PCT, loop of Henle, DCT, collecting duct
  5. List the substances that are filtered out during ultrafiltration
    Ans. Water, amino acid, glucose, urea, uric acid, minerals, vitamins.
  6. What are the substances reabsorbed by the nephron?
    Ans. Water, glucose, some salts, amino acid and small quantity of urea and uricacid.
  7. What is the importance of tubular secretion?
    Ans. Direct elimination of certain minerals can take place such as ammonia andpotassium.
  8. Under which situation are the following present?
    (a) Glucose in the urine – Diabetes mellitus
    (b) Uric acid crystals – Gout
  9. What is the normal volume of urine excreted per day?
    Ans. 1200 to 1500 mL
  10. What will happen if JGA (juxtaglomerular apparatus) stops secreting the enzymerenin?
    Ans. Blood Pressure will remain abnormally low.
  11. Name a hormone, which is a polypeptide in nature and secreted by the heart muscles and is also a vasodilator.
    Ans. Antinatriuretic factor.


  1. Name the organ where urea is formed. – Liver
  2. Why is cellophane used in haemodialysis?
    Ans. Cellophane is impermeable to macromolecules like plasma proteins andblood corpuscles
  3. What is the composition of dialyzing fluid?
    Ans. It contains some minerals and solutes like those in plasma but no ureaand uric acid is present.
  4. From which type of blood vessel artery or vein, is the blood taken out for dialysis?
    Ans. Artery
  5. When is kidney transplantation advised?
    Ans. When kidney failure cannot be treated.
  6. How is bile pigment removed from our body?
    Ans. Bile pigments are removed along with bile via the digestive tract.


  1. List the major steps that are involved with respiration in humans.
  2. How is oxygen transported in earthworm?
  3. Name the respiratory pigment in earthworm.
  4. What is the role of carbonic anhydrase in the transport of carbon dioxide in ourbody?
  5. Which part of our respiratory system is known as the voice box?
  6. Where are respiratory centres situated in our brain?
  7. Name one nitrogenous waste removed by the kidney. Plants and animals
  8. Name the hormone the absence of which will result in excretion of hypotonicurine.
  9. What is the role of cellophane in dialysis?
  10. Why is inspiration said to be an active phase and expiration as passive phase?
  11. Differentiate between
    (a) Breathing and respiration
    (b) Inspiration and expiration
  12. List the special features of alveoli that enable easy gaseous exchange.
  13. What is vital capacity, tidal volume and residual volume?
  14. Give reasons for the following :
    (a) Exchange of gases at the alveolar surface continues even during expiration.
    (b) Trachea and bronchi do not collapse when air pressure decreases insidethem.
  15. Draw the excretory system of human and label the parts.
  16. Draw the structure of a nephron and label the parts.
  17. What is the cause and symptoms of pneumonia and TB?
  18. What is the role of liver in excretion?
  19. Explain how nitrogenous wastes are removed from the body of cockroach.
  20. How does ultrafiltration and reabsorption occur in nephrons?
  21. Explain how gaseous exchange takes place in the lungs.
  22. How is oxygen transported from the lungs to the tissues and carbon dioxide from tissues to the lungs?
  23. How is (a)Water balance, and (b) Salt balance maintained by kidney?
  24. List the parts of human respiratory system in correct sequence and state theirfunctions.
  25. List three characteristics of our lungs which make them suitable as respiratory surface

NIOS 12th class biology Q Ans

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