Title Ex- 1 Breathng and Exchange of Gases (Solution file).docx.pdf ✅

96 BREATHING AND EXCHANGE OF GASES EXERCISE – 1: Basic Objective Questions Breathing and respiration 1. In which of the following lower invertebrates exchange of oxygen with CO2 by simple diffusion over the entire body surface takes place (a) sponges (b) coelenterates (c) flatworms (d) all of these Ans. (d) Sol. Lower invertebrates like sponges, coelenterates, flatworms, etc. use their entire body surface for gaseous exchange. Oxygen gets diffused inside through the moist body surface while CO2 diffuses outside. 2. Network of tubes (tracheal tubes) is commonly present in (a) earthworm (b) sponges (c) flatworms (d) insects Ans. (d) Sol. Insects have a network of tubes called tracheal tubes. They use them to breath in the atmospheric air and to transport it into the body. 3. Which of the following vertebrates respire through gills (a) molluscs (b) fishes (c) aquatic arthropods (d) all of these Ans. (d) Sol. Fishes are the aquatic vertebrates which commonly use a set of thin, vascularized structure for the gaseous exchange in water. It is known as gills. Aquatic arthropods and molluscs also use gills as respiratory organs. 4. The breakdown of nutrient molecules like glucose and to derive energy for performing various activities is a catabolic reaction. The harmful gaseous substance released during this process is (a) O2 (b) CO2 (c) N2 (d) CO Ans. (b) Sol. The breakdown of molecules like glucose is a catabolic process known as respiration which involves sequential steps that gradually release the energy. The O2 is used in this process while CO2 is released. If CO2 is accumulated and not released through expiration it may be harmful. 5. Match the columns I and II and choose the correct combination from the options given. Column I Column II a . Sponges 1 . Gills b . Flatworms 2 . Lungs c . Earthworms 3 . Entire body surface d . Insects 4 . Moist cuticle e . Aquatic arthropods 5 . Tracheal tubes (a) a-3, b-1, c-4, d-5, e-2 (b) a-1, b-3, c-1, d-4, e-2 (c) a-3, b-3, c-4, d-5, e-1 (d) a-3, b-2, c-4, d-5, e-1 Ans. (c) Sol. -Sponges are lower organisms of kingdom Animalia and do not have any specialized respiratory organ. They breathe through their entire body surface. -Flatworms respire through the entire body surface as their skin is really thin. Earthworms live in soil and moist surfaces and usually breathe through their specialized moist skin called the cuticle. Insects have tube-like structures for exchange of gases divided in their whole body, these tubes are called tracheal tubes. Aquatic arthropods like crustaceans respire through gills. Respiratory Organs in Animals 6. The respiratory or the exchange part of the respiratory system is formed by (a) From external nostrils up to the alveoli
97 BREATHING AND EXCHANGE OF GASES (b) From external to internal bronchioles (c) From trachea to terminal bronchioles (d) Alveoli and duct of alveoli Ans. (d) Sol. Air passes through the conducting parts from nostrils to bronchioles but the exchange of gases occurs in alveoli and its ducts. Alveoli are small bag-like structures which are richly supplied with blood vessels. It has a very thin membrane to facilitate diffusion of oxygen and carbon dioxide through it. 7. The dorsal, ventral, lateral and lower surfaces of thoracic chamber are formed by (a) vertebral column, sternum, ribs and diaphragm (b) sternum, ribs, vertebral column and diaphragm (c) ribs, diaphragm, vertebral column and sternum (d) vertebral column, sternum, diaphragm and ribs Ans. (a) Sol. The thoracic chamber is bordered by vertebral column on dorsal, sternum on ventral, ribs on lateral and diaphragm on lower surface. 8. A fully grown tadpole larva of Frog respires through (a) Skin (b) Gills (c) Lungs (d) Tail fin Ans. (b) Sol. Tadpoles of frogs live in water and therefore respire through gills. Skin performs respiratory functions in adult frogs. During metamorphosis, the lungs develop and gradually become functional after the tadpole loses its tail and develops limbs. 9. Book lungs are respiratory structures is (a) Arthropoda (b) Mollusca (c) Mammals (d) Annelida Ans. (a) Sol. Book lungs are present in class Arachnida of phylum Arthropoda. These have four pairs of jointed legs. This class includes terrestrial arthropods like spiders and scorpions. Book lungs have many respiratory membranes together arranged in a book-like fashion. Earthworms (Annelids), molluscs or mammals do not have such respiratory structures. Human Respiratory System 10. Assertion: Tracheae, primary, secondary and tertiary bronchi are supported by incomplete cartilaginous rings. Reason: These rings of cartilage make the wall non-collapsible. (a) If both assertion and reason are true and reason is the correct explanation of assertion. (b) If both assertion and reason are true but reason is not the correct explanation of assertion. (c) If assertion is true but reason is false. (d) If both assertion and reason are false. Ans. (a) Sol. The trachea extends from the larynx and moves up to the bronchi of the lungs. The bronchi are branched into primary, secondary and tertiary bronchi. It facilitates the passage and movement of air into the lungs. The trachea consists of various numbers of cartilaginous rings. The rings are horseshoe shaped and are incomplete. The non-collapsible nature of the rings is formed by the cartilaginous tissues. The cartilaginous rings are further joined by the ligaments which support them. The trachealis muscles run along the back wall of the trachea. 11. Normal breathing rate of a healthy human is (a) 70-75 times/minute (b) 15-20 times/minute (c) 12-16 times/minute (d) 10-12 times/minute Ans. (c) Sol. Breathing rate is the number of breaths a person takes per minute and this rate is measured when a person is at rest by counting how many times the chest rises. The normal breathing rate for an adult person at rest ranges from 12 to 16 breaths per minute. 12. The lungs are situated in a thoracic chamber which is formed dorsally by the ...a..., ventrally by the ...b..., laterally by the ...c... and on lower side by the ...d... (a) b-sternum, c-diaphragm, a-vertebral column, d-ribs (b) a-sternum, c-diaphragm, b-vertebral column, d-ribs (c) b-sternum, d-diaphragm, a-vertebral column, c-ribs
98 BREATHING AND EXCHANGE OF GASES (d) d-sternum, c-diaphragm, a-vertebral column, b-ribs Ans. (c) Sol. Lungs are soft organs and hence a bony rib cage is present to protect it. The ribs are attached to the vertebral column dorsally and ventrally with a sternum. The sternum is a flat bone present in the middle of the chest. Lungs are protected laterally with ribs. At the bottom of the lungs, a dome-shaped structure called diaphragm is present which contracts during inspiration and relaxes when we exhale. 13. The covering of the lung is called (a) Pericardium (b) Perichondrium (c) Pleural membrane/pleura (d) Peritoneum Ans. (c) Sol. Lungs are covered by pleural membrane or pleura which is a double membrane structure. Pleural fluid is present between the two layers which are protective in nature and helps in reducing friction between the two membranes during contraction and relaxation of the lungs. 14. Breathing rate is lowest while we are: (a) eating (b) sleeping (c) playing tennis (d) delivering orders Ans. (b) Sol. It is because our body is at rest and the functions going in our body slow down and the response to external stimuli decreases. At this time, the oxygen levels are low and carbon dioxide levels are high when a person is asleep. 15. Conducting part of the respiratory system is formed (a) From external nostrils up to the initial bronchioles (b) From external nostrils up to the terminal bronchioles (c) From external nostrils up to the duct of alveoli (d) From external nostrils up to the alveoli Ans. (b) Sol. Conducting part of the respiratory system includes all the structures which help in the passage of air from outside the body to the alveoli where the actual exchange of gases occurs. Conducting part follows the path: Nostrils → Nasal chamber → Nasopharynx → Larynx → Trachea → Bronchi → Secondary bronchi → Tertiary bronchi → Terminal bronchioles. Each terminal bronchiole ends into a small vascularized bags called alveoli. 16. The lungs are covered by pleura which is (a) single layered (b) double layered (c) triple layered (d) multiple layered Ans. (b) Sol. The pleura is a thin covering around the lungs. It is double layered. Pleural fluid is present between the two layers of pleura. 17. Recognize the figure and find out the correct matching (a) e-alveoli, f-bronchus, d-bronchiole, a-trachea, c-larynx, b-epiglottis (b) f-alveoli, d-bronchus, e-bronchiole, c-trachea, b-larynx, a-epiglottis (c) f-alveoli, e-bronchus, d-bronchiole, c-trachea, a-larynx, b-epiglottis (d) f-alveoli, d-bronchus, e-bronchiole, b-trachea, c-larynx, a-epiglottis Ans. (b) Sol. The figure shows the respiratory system in humans. Epiglottis (shown by a) is a cartilaginous flap partially covering the larynx. Larynx is also called the
99 BREATHING AND EXCHANGE OF GASES sound box, is present in the neck region shown by label ‘b’. Larynx joins lungs through trachea and bronchus (shown by c and d respectively) which are tube-like structures. Bronchus further divides into bronchi and terminal bronchioles (shown by label ‘e’). These bronchioles terminate into small bag-like structures with very thin membranes called alveoli (shown by f). 18. Match the columns. a. Larynx p. Lid of larynx b. Trachea q. Air sacs c. Alveoli r. Voice box d. Epiglottis s. Wind pipe t. Common passage (a) a-r, b-s, c-q, d-p (b) a-t, b-s, c-p, d-q (c) a-r, b-s, c-q, d-t (d) a-r, b-t, c-q, d-p Ans. (a) Sol. The larynx is a cartilaginous structure which helps in the production of sound and is called a soundbox. Trachea/Windpipe is a tube-like structure through which the air passes. Alveoli are small sacs in which the exchange of gases takes place. Epiglottis is a flap-like structure which covers the larynx to avoid the entry of food into it during swallowing. 19. Layer of uneven columnar cells which form tracheal lining are component of (a) Brush border epithelium (b) Stratified epithelium (c) Pseudostratified epithelium (d) Ciliated epithelium Ans. (c) Sol. The trachea has linings of the pseudostratified epithelium. They also have cilia to trap the dust and foreign particles passing through them. Pseudostratified epithelium appears like layers of epithelial cells due to their nuclei arranged in a random manner and hence gives a false layered appearance. 20. Even when there is no air in it, trachea does not collapse due to the presence of: (a) bony rings (b) turgor pressure (c) chitinous rings (d) cartilaginous rings Ans. (d) Sol. The trachea is surrounded by a number of incomplete or C-shaped cartilaginous rings. The trachea is incompletely covered by cartilaginous rings on the dorsal side. These rings support the trachea and prevent it from collapsing. 21. The function of tracheal hairs is to: (a) pass air in (b) pass air out (c) pass mucus in (d) pass mucus out Ans. (d) Sol. Tracheal hairs are also known as cilia present in the trachea that pass the mucus containing debris and foreign particles out of the trachea through the ciliary movement of its hairs. This process is to keep lung and windpipe out of dirt and antigens. 22. Glottis is an opening in the floor of (a) mouth (b) trachea (c) pharynx (d) diaphragm Ans. (c) Sol. Glottis is the opening on the floor of pharynx and opens into the windpipe. It is the initial part of the larynx which is covered by the epiglottis. Larynx joins the trachea which divides into bronchi and bronchioles for conducting air to the lungs.