Chapter 14 Respiration and Elimination of Nitrogenous Wastes

NIOS Biology Intext Solutions Chapter 14

INTEXT QUESTIONS 14.1

1. Define respiration

Ans: Respiration is the stepwise oxidation of glucose (and other nutrients), which results in the release of energy that is stored in the cytosol in the form of ATP (adenosine triphosphate).

2. Name the two gases that are exchanged during respiration.

Ans: O₂ is taken in and CO₂is breathed out.

3. What is cutaneous respiration? Name one animal that undertakes cutaneous respiration.

Ans: In cutaneous respiration, the respiration through the skin, the moist skin or organisms take up O₂ dissolved in the water (in the moisture). Earthworms exhibit cutaneous respiration.

4. What is the colour of the blood of the earthworm? Name the pigment responsible for the colour.

Earthworms have red-coloured blood due to the presence of haemoglobin.

5. How is oxygen transported to the cells in the cockroach?

Ans: Cockroach respires by means of internal tubes called tracheae. These tubes branch out extensively inside the body and carry air directly to the tissues from the atmosphere.

Tracheae open up to the exterior by paired slit like apertures called spiracles. Spiracles are found on the sides of the thorax and abdomen.
The fine branches of tracheal trunks called tracheoles finally penetrate the cells of the body and allow diffusion of respiratory gases directly into and from the cells.
The ends of the tracheoles are thin and filled with fluid in which respiratory gases dissolve. The inflow and outflow of air are affected by the alternate contraction and expansion of the abdomen.

6. Name the group of animals in which blood is not involved in gaseous exchange.

Ans: Insects

7. How does trachea communicate with the exterior in cockroach?

Ans: Tracheae in cockroach open up to the exterior by paired slit like apertures called 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: The Epiglottis is a flap-like structure that closes the tracheal opening (opening of the windpipe) called the glottis when food is swallowed. It helps prevent the food from entering the trachea or the food pipe

INTEXT QUESTIONS 14.2

1. What is breathing?

Ans: Breathing is a mechanical process of taking in atmospheric air into the lungs and giving out carbon dioxide.

2. What is the position of the diaphragm at the time of expiration?

Ans: During expiration, the diaphragm is relaxed relaxes and rises again into its original dome-shaped condition.

3. What is the capacity of tidal volume?

Ans: 500 mL

4. What is the maximum number of oxygen molecules with which haemoglobin can combine?

Ans: 4 molecules

5. Name the blood vessel that takes oxygenated blood from the lungs to the heart.

Ans: 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: BCG: Bacillus Calmette-Guérin

8. What is an occupational hazard?

Ans: Silicosis or asbestosis is caused due to exposure to harmful substances like silica, asbestos, dust, etc.

present in the environment where a person works.

9. What is the difference between bronchitis and asthma?

Ans: Bronchitis is an Inflammation of the bronchi caused by infection. caused by infection. It can also be caused by smoking and by exposure to air pollution. On the other hand, bronchial asthma is an allergic disease caused due to certain foreign substances in the air.

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

INTEXT QUESTIONS 14.3

1. Name the organ where urea is produced and the organ from where urea is excreted.

Ans: (a) Liver (b) Kidney

2. Which is the most toxic form of nitrogenous waste? Name an organism that excretes it.

Ans: Ammonia is the most toxic form of nitrogenous waste.

Amoeba and freshwater fishes excretes ammonia.

INTEXT QUESTIONS 14.4

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: The malpighian tubules are long, blind ended tubules attached to the alimentary canal at the junction of mid and hindgut.

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
The 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 acids, glucose, urea, uric acid, minerals, vitamins.

6. What are the substances reabsorbed by the nephron?

Ans: Water, glucose, some salts, amino acids and a small quantity of urea and uric acid.

7. What is the importance of tubular secretion?

Ans: Cells of the renal tubule also directly secrete certain unwanted substances from the

blood into the filtrate. These include uric acid, K+ ions and ammonia. This direct elimination of these substances occurs through tubular secretion.

8. Under which situation are the following present?

(a) Glucose in the urine.

(b) Uric acid crystals …..

Ans:

(a) Diabetes mellitus
(b) 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 enzyme renin?

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.

INTEXT QUESTIONS 14.5

1. Name the organ where urea is formed.

Ans: Liver

2. Why is cellophane used in haemodialysis?

Ans: Cellophane is permeable to micro molecules such as urea, uric acid and mineral ions. It is not permeable to macromolecules such as plasma proteins.

3. What is the composition of dialyzing fluid?

Ans: It contains some minerals and solutes like those in plasma, but no urea and uric acid are 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: If kidney failure cannot be treated by other available means, kidney transplantation is advised.

6. How is bile pigment removed from our body?

Ans: The liver excretes bile pigments, cholesterol, drugs and some vitamins in bile, which flows into the small intestine, and from there these get removed with the faeces.