Respiratory organs Questions in English

(A) Respiration in $Cnidarians$ (such as $Hydra$ and $Jellyfish$) occurs through the process of simple diffusion.
Since these organisms have a simple body organization and are in direct contact with the surrounding water,dissolved oxygen enters their body cells,and carbon dioxide leaves the body through the general body surface via diffusion.
Fishes use gills,while amphibians and reptiles primarily use lungs or skin (in some cases) but do not rely solely on simple diffusion across the entire body surface like $Cnidarians$.

(D) Earthworms do not possess specialized respiratory organs like lungs or gills.
They respire through their moist skin,a process known as cutaneous respiration.
In contrast,mosquito larvae use spiracles/siphons,tadpoles use gills,and cockroaches use a tracheal system for respiration.

(B) Insects possess a network of air tubes called tracheal tubes.
These tubes open to the exterior through small pores known as spiracles.
Oxygen from the air enters through the spiracles and travels directly to the tissues via the tracheal system,bypassing the circulatory system.
Therefore,oxygen is carried to different tissues by tracheal tubes.

(A) Respiration in animals occurs through various specialized organs depending on their habitat and evolutionary complexity.
$A$. Prawns are aquatic arthropods belonging to the class $Crustacea$. They respire using specialized respiratory organs called gills.
$B$. Frogs are amphibians that can respire through skin (cutaneous respiration),lungs (pulmonary respiration),and the buccal cavity.
$C$. Crocodiles are reptiles that respire exclusively through lungs.
$D$. Whales are aquatic mammals that respire through lungs and must surface to breathe air.
Therefore,the correct answer is Prawn.

(A) Crustaceans are a large group of arthropods,primarily aquatic,which include animals like crabs,lobsters,and prawns.
In these aquatic arthropods,respiration occurs through specialized respiratory organs known as gills.
$A$ is the correct option because gills are the primary respiratory structures in crustaceans.
$B$ (Book lungs) are found in arachnids like spiders and scorpions.
$C$ (Ctenidia) are respiratory organs found in mollusks.
$D$ (Trachea) is the respiratory system found in insects.

(B) Insects possess a network of air tubes called $Tracheae$ for respiration.
These tubes open to the outside through small pores known as $Spiracles$.
Oxygen enters the $Tracheal$ system directly and reaches the tissues,while carbon dioxide is expelled through the same system.
Therefore,the correct mode of respiratory gas exchange in insects is through $Tracheae$.

(C) The correct option is $C$.
$1.$ Silver fish belongs to the class Insecta,which uses trachea for respiration.
$2.$ Scorpion belongs to the class Arachnida,which uses book lungs for respiration.
$3.$ Sea squirt (Herdmania) belongs to the subphylum Urochordata,which uses pharyngeal gills for respiration.
$4.$ Dolphin is a mammal,and it breathes through lungs,not skin. Therefore,the matching for the dolphin is incorrect.

(A) Frogs lack a diaphragm,which is the primary muscle responsible for creating negative pressure in the thoracic cavity of mammals to facilitate breathing.
Because they do not have a diaphragm or a rib cage that can expand to create a vacuum,they use a mechanism called 'buccopharyngeal respiration' or positive pressure breathing.
In this process,the frog swallows air by closing its nostrils and raising the floor of its mouth,which forces air into the lungs.

(D) In hydrophytes (aquatic plants),the respiratory exchange of gases occurs through the general body surface via diffusion. Since these plants are submerged or floating in water,they lack specialized structures like stomata or lenticels for gas exchange in the submerged parts,and the entire surface area of the plant is in direct contact with the surrounding water or air,allowing for efficient diffusion.

(C) Seeds are covered by a hard seed coat called the testa.
However,they require oxygen for respiration during germination.
The respiratory gases ($O_2$ and $CO_2$) enter and exit the seed primarily through a small pore known as the micropyle.
Therefore,the micropyle serves as the site for respiratory exchange in seeds.

(D) The correct answer is $D$.
Earthworms do not possess specialized respiratory organs like lungs or gills.
They perform gaseous exchange directly through their moist and slimy skin,a process known as cutaneous respiration.

(D) Scorpions belong to the class $Arachnida$ of the phylum $Arthropoda$.
They possess specialized respiratory structures known as $Book$ $lungs$.
These structures consist of a series of thin,leaf-like folds of the body wall arranged like the pages of a book,which are located within an internal chamber and are adapted for gas exchange in terrestrial environments.

(D) The correct answer is $D$. Crustaceans typically respire using gills,and in some cases,through the general body surface. They do not use lungs for respiration. Therefore,the pair $Crustaceans - Lungs$ is incorrect.

(A) The diaphragm is a characteristic muscular partition found only in mammals that aids in breathing by changing the volume of the thoracic cavity.
$A$. Frog is an amphibian and lacks a diaphragm; it uses buccal cavity,skin,and lungs for respiration.
$B$. Rat,$C$. Camel,and $D$. Rabbit are all mammals and possess a diaphragm that plays a crucial role in their respiratory mechanism.

(D) In many species of snakes,the left lung is either significantly reduced or completely absent due to their elongated body shape. Consequently,they possess only a single,functional right lung to facilitate respiration. Therefore,the correct answer is $(d)$.

(B) The eggshell of a bird is porous, which allows for the exchange of gases ($O_2$ and $CO_2$) between the developing embryo and the external environment.
Plaster of Paris $(CaSO_4 \cdot 1/2 H_2O)$ forms a hard, non-porous layer when it sets.
If the egg is covered with this material, the pores in the shell are blocked.
This prevents the diffusion of gases, thereby hindering the respiration of the developing chick embryo, which eventually leads to its death.

(D) Submerged hydrophytes are plants that grow entirely underwater.
Since they are completely submerged,they lack functional stomata because stomata would be ineffective for gas exchange in an aquatic environment.
Instead,these plants absorb dissolved gases like $CO_2$ and $O_2$ directly from the surrounding water through their general body surface via diffusion.
Therefore,the correct answer is the general surface.

(D) Hydrophytes are aquatic plants that live in water.
Floating leaves of hydrophytes often have a waxy cuticle on their upper surface.
The primary function of this waxy layer is to prevent the clogging of stomata by water and to reduce excessive water loss through transpiration,although in floating leaves,the stomata are restricted to the upper surface.
However,the most direct functional consequence of the waxy coating in this context is to prevent the stomata from getting blocked by water,which would otherwise hinder gas exchange.

(A) Fish use gills for respiration,which are specialized organs designed to extract dissolved oxygen from water. When a fish is removed from water,the gill filaments collapse and stick together due to surface tension. This drastically reduces the surface area available for gas exchange,preventing the fish from obtaining sufficient oxygen,leading to suffocation and death.

(A) Crustaceans,which belong to the phylum $Arthropoda$,primarily inhabit aquatic environments. In these organisms,respiration takes place through specialized respiratory organs known as gills $(branchiae)$. While some terrestrial arthropods use book lungs or tracheae,gills are the characteristic respiratory structures for aquatic crustaceans.

(B) In insects,the respiratory system consists of a network of tubes called the $Tracheal$ $system$.
These tubes open to the outside through small pores called spiracles.
Oxygen enters through these spiracles and is directly delivered to the tissues via the tracheal tubes,bypassing the blood.
Therefore,insects do not require respiratory pigments like hemoglobin for oxygen transport.

(D) The diaphragm is a characteristic muscular structure found in mammals that separates the thoracic cavity from the abdominal cavity.
Rabbit,Human,and Bat are all mammals,and therefore,they possess a diaphragm.
Frog belongs to the class Amphibia.
Amphibians do not possess a diaphragm; instead,they use buccal pumping and skin respiration to facilitate breathing.
Therefore,the diaphragm is absent in the frog.

(B) Insects belong to the phylum $Arthropoda$.
They possess a specialized respiratory system consisting of a network of air tubes called $tracheae$.
These tubes open to the exterior through small pores known as $spiracles$.
This system allows for the direct exchange of gases between the atmosphere and the body tissues,independent of the circulatory system.

(C) In many lower invertebrates,respiration occurs through the body surface by simple diffusion.
Skin (cutaneous respiration) is considered a simple respiratory organ found in organisms like earthworms and amphibians.
Gills,lungs,and contractile vacuoles are either complex respiratory structures or serve different physiological functions (like osmoregulation in the case of contractile vacuoles).
Therefore,skin is the correct answer.

(B) The respiratory pigment that contains copper $(Cu)$ is Hemocyanin.
Hemocyanin is a protein that transports oxygen throughout the bodies of some invertebrate animals.
Unlike hemoglobin,which contains iron $(Fe)$ and is found in red blood cells,hemocyanin is found free-floating in the hemolymph of mollusks and arthropods.
When oxygenated,hemocyanin appears blue in color due to the presence of copper ions.

(D) The earthworm ($Pheretima$ $posthuma$) does not have specialized respiratory organs like lungs or gills.
It performs gaseous exchange through its moist skin,a process known as cutaneous respiration.
In contrast,frogs use lungs and skin,cockroaches use a tracheal system,and fish use gills for respiration.

(C) The earthworm ($Pheretima$ $posthuma$) does not possess any specialized respiratory organs like lungs or gills.
It performs respiration through its moist skin,a process known as cutaneous respiration.
The gases ($O_2$ and $CO_2$) diffuse directly through the thin,moist,and highly vascularized body wall into the blood capillaries.
In contrast,rabbits use lungs,cockroaches use a tracheal system,and frogs use both lungs and skin (though they possess lungs as primary organs).

(C) Spiracles are small external openings found in the exoskeleton of insects and some other arthropods.
These openings are connected to the tracheal system,which is a network of tubes that deliver oxygen directly to the tissues of the body.
Therefore,spiracles are primarily involved in the process of respiration by allowing the exchange of gases between the internal tracheal system and the external environment.

(B) The silkworm $(Bombyx \ mori)$ is an insect. Insects respire through a network of air tubes called the trachea. Air enters the body through small openings on the sides of the body known as spiracles and travels through the tracheal system to reach the tissues directly. Therefore,the respiratory organ of a silkworm is the trachea.

(C) In the phylum $Arthropoda$,respiration occurs through various specialized organs depending on the habitat and species.
$1$. $Gills$ are used by aquatic arthropods like prawns.
$2$. $Trachea$ (tracheal system) is a common respiratory organ in insects.
$3$. $Book$ $lungs$ are found in arachnids like scorpions and spiders.
$4$. $Lungs$ are characteristic of vertebrates (like mammals,birds,and reptiles) and are not present in arthropods.
Therefore,$Lungs$ is the correct answer.

(C) The correct option is $C$.
$1$. Sponges,coelenterates,and flatworms exchange $O_2$ with $CO_2$ by simple diffusion over their entire body surface. They do not have a specialized respiratory system.
$2$. Earthworms use their moist skin (cutaneous respiration) for gas exchange,not gills.
$3$. Aquatic arthropods (like crustaceans) respire through gills.
$4$. Terrestrial arthropods (like insects) respire through a network of tubes called the tracheal system,not lungs.

(A) In lower invertebrates like sponges,coelenterates,and flatworms,the exchange of oxygen and carbon dioxide occurs through simple diffusion across the entire body surface or the outer layer of the body.
This is because these organisms have a simple body organization and a high surface-area-to-volume ratio,which allows for efficient gas exchange without the need for specialized respiratory organs.

(B) The matching of organisms with their respiratory organs is as follows:
$(p)$ Sponges respire through simple diffusion over their entire body surface $(IV)$.
$(q)$ Insects respire through a network of tracheal tubes $(I)$.
$(r)$ Molluscs (aquatic) respire through vascularized gills $(III)$.
$(s)$ Reptiles respire through lungs $(II)$.
Therefore,the correct sequence is $p-IV, q-I, r-III, s-II$,which corresponds to $IV - I - III - II$.

(D) In amphibians like the $Frog$ $(Rana \, tigrina)$, the skin is moist and highly vascularized, which allows for cutaneous respiration. This means they can exchange gases directly through their skin, especially when they are underwater or in moist environments. Other options like lizards, birds, and mammals primarily use lungs for respiration.

(D) Let us analyze the respiratory organs of the given animals:
$1$. Silverfish (an insect) respires through a tracheal system (Trachea). This is correct.
$2$. Scorpion (an arachnid) respires through book lungs. This is correct.
$3$. Sea squirt (a Urochordate/Tunicate) respires through pharyngeal gill slits. This is correct.
$4$. Dolphin (a mammal) respires through lungs,not skin. This is incorrect.
Therefore,the correct pairs are $(a)$,$(b)$,and $(c)$.

(B) In amphibians like the $Frog$ $(Rana \, tigrina)$, the skin is moist and highly vascularized, which allows for cutaneous respiration. This serves as an accessory respiratory organ, especially when the animal is underwater or hibernating, supplementing the primary pulmonary respiration.

(D) The blood of insects,known as hemolymph,is colourless because it lacks respiratory pigments like hemoglobin. Therefore,the Assertion is incorrect. The Reason is correct because insect blood does not transport $O_2$; instead,insects utilize a tracheal system for gas exchange,where air is delivered directly to tissues via tracheae.

(C) In insects,gaseous exchange occurs through a network of tubes collectively known as the tracheal system.
The small openings on the sides of an insect's body are known as spiracles.
Oxygen-rich air enters through the spiracles,which are connected to the network of tubes called tracheae.
From the tracheae,oxygen diffuses directly into the cells of the body.
The movement of carbon dioxide $(CO_{2})$ follows the reverse path,where $CO_{2}$ from the cells enters the tracheae and leaves the body through the spiracles.

(N/A) Mechanisms of breathing vary among different groups of animals,depending mainly on their habitats and levels of organization. Simple organisms exchange gases by simple diffusion over their entire body surface,while complex organisms have evolved specialized respiratory organs.

$1$. Animal Group	$2$. Respiratory Organ
Lower Invertebrates (Porifera,Coelenterata,Platyhelminthes)	Entire body surface (Diffusion)
Annelida	Moist cuticle (Cutaneous respiration)
Arthropoda (Insects)	Tracheal system
Arthropoda (Aquatic - Crustaceans)	Gills (Branchial respiration)
Arthropoda (Arachnids)	Book lungs/Book gills
Mollusca	Gills (Ctenidia)
Echinodermata	Tube feet/Dermal branchiae
Amphibians	Moist skin,lungs,and buccal cavity
Reptiles,Birds,Mammals	Lungs (Pulmonary respiration)
Fishes	Gills

(N/A) In woody plants,the bark is covered by a layer of cork which is impermeable to gases.
To facilitate gas exchange,small pores called $Lenticels$ are present on the surface of the bark.
These $Lenticels$ allow for the diffusion of oxygen and carbon dioxide between the internal tissues and the external environment.
Additionally,they also facilitate a small amount of transpiration.

(N/A) Flatworm: Respiration occurs through the general body surface via diffusion.
$(b)$ Birds: Respiration occurs through a pair of lungs.
$(c)$ Frog: Respiration occurs through moist skin (cutaneous respiration),oral cavity,and lungs (pulmonary respiration).
$(d)$ Cockroach: Respiration occurs through a network of tubes called the tracheal system.

(A) The diaphragm is a characteristic muscular partition found only in mammals,which plays a crucial role in the mechanism of breathing by changing the volume of the thoracic cavity.
Among the given options,$Rat$,$Camel$,and $Rabbit$ are mammals and possess a functional diaphragm for respiration.
$Frog$ is an amphibian and lacks a diaphragm; instead,it uses buccal cavity pumping and cutaneous respiration to facilitate gas exchange.

(B) Various types of respiratory structures are present in different groups of arthropods.
The tracheal system is a network of air tubes that serves as the primary organ for respiration in many arthropods,including insects.
It allows for the direct exchange of gases between the atmosphere and the body tissues.

(D) The correct answer is $D$.
Insects possess a tracheal system which is sufficient to transport oxygen directly to the tissues.
The tracheal system forms a network of tubes,and its branches,known as tracheoles,reach every part of the body.
Because oxygen is delivered directly to the cells via the tracheal system,insects do not require respiratory pigments in their blood (haemolymph) for gas transport.

(D) Unlike animals,plants do not possess specialized respiratory organs for gaseous exchange. Instead,they utilize various structures to facilitate the diffusion of gases. Stomata,found primarily on the surface of leaves,and lenticels,found on the bark of woody stems and roots,are the primary sites for gaseous exchange in plants.

(A) Book lungs are specialized respiratory structures found in arachnids like spiders and scorpions. They are named so because their internal folds resemble the pages of a book. In these organs,the exchange of gases occurs between the interlamellar spaces and the venous blood through the thin,membranous walls of the lamellae.

(D) The mechanism of breathing varies among different groups of animals,depending mainly on their habitats and level of organization.
Lower invertebrates such as sponges $(I)$,coelenterates $(II)$,and flatworms $(III)$ exchange $O_{2}$ with $CO_{2}$ by simple diffusion over their entire body surface.
Therefore,all the listed organisms perform gas exchange through this method.

(B) Respiration through the skin is known as cutaneous respiration.
In amphibians,such as frogs and toads,the skin acts as an accessory respiratory organ,especially when they are in water or during hibernation.

(C) According to the $NCERT$ textbook,among vertebrates,fishes use gills for respiration.
Reptiles,birds,and mammals respire through lungs.
Amphibians like frogs can respire through their moist skin in addition to lungs.
Therefore,the correct sequence for the blanks is $A-$ fishes,$B-$ lungs,$C-$ moist skin.