Class-Mammalia Questions in English

(B) The presence of an external ear or pinna is a unique and defining characteristic of the class $Mammalia$.
Birds do not have an external pinna; instead,they have small openings covered by feathers.
Reptiles also lack an external pinna and typically have a tympanum representing the ear.
Therefore,the correct option is $B$.

(C) The blue whale $(Balaenoptera musculus)$ is the largest mammal currently living on Earth. It belongs to the order $Cetacea$. While dinosaurs were large reptiles,they are not mammals. Elephants and rhinoceroses are large land mammals,but they are significantly smaller than the blue whale.

(C) Both birds $(Aves)$ and bats $(Mammalia)$ possess wings for flight and are homeothermic (warm-blooded) with a four-chambered heart.
However, the presence of a $diaphragm$ is a characteristic feature unique to mammals.
Birds lack a diaphragm; instead, they possess an air sac system associated with their lungs for efficient respiration.
Therefore, the presence of a diaphragm is the key anatomical feature that distinguishes bats from birds.

(A) Viviparous animals are those that give birth to live young ones instead of laying eggs.
Among the given options,$A$ (Dolphin) is a mammal that is viviparous.
$B$ (Platypus) is an oviparous mammal (egg-laying).
$C$ (Ostrich) and $D$ (Penguin) are birds,and all birds are oviparous.

(D) The presence of a pinna (external ear) is a unique characteristic feature of the class $Mammalia$.
Other classes like $Reptilia$,$Aves$,and $Amphibia$ do not possess an external ear or pinna.

(D) The bat is a flying mammal. It belongs to the class $Mammalia$ because it possesses mammary glands,has hair on its body,and gives birth to young ones rather than laying eggs.

(B) Assertion $(P)$ is true because most mammals give birth to young ones (viviparous),although there are exceptions like monotremes (e.g.,platypus).
Reason $(Q)$ is also true because the presence of external ears or pinnae is a characteristic feature of mammals.
However,the fact that mammals are viviparous is not caused by the presence of external pinnae. These are two independent characteristics of the class Mammalia.
Therefore,both statements are true,but $P$ is not the correct explanation of $Q$.

(A) The animal shown in the figure is the Platypus (Ornithorhynchus anatinus).
Platypus is a unique mammal that belongs to the order Monotremata.
Unlike most mammals which are viviparous (giving birth to live young),monotremes are oviparous,meaning they lay eggs.
Therefore,the correct option is $(A)$.

(A) Mammals are generally viviparous, meaning they give birth to live young. However, there is a small group of mammals known as monotremes that lay eggs. The $Duck-billed$ $platypus$ $(Ornithorhynchus$ $anatinus)$ is a classic example of an oviparous mammal. Penguins are birds, and dolphins are viviparous mammals. Therefore, the correct option is $A$.

(B) Both statements are correct. Bats and whales are mammals because they possess mammary glands,hair,and give birth to young ones. $A$ characteristic feature of mammals is the presence of a four-chambered heart (two atria and two ventricles),which ensures complete separation of oxygenated and deoxygenated blood. Since the four-chambered heart is a defining anatomical trait that supports the high metabolic demands of mammals,statement $Q$ explains why they are classified as mammals. Therefore,$Q$ is the correct explanation for $P$.

(B) Viviparous animals are those that give birth to live young ones instead of laying eggs.
$1$. Kangaroo,Dolphin,Rat,and Whale are all mammals.
$2$. Most mammals are viviparous.
$3$. Platypus is an oviparous (egg-laying) mammal.
$4$. Penguins,crocodiles,and ostriches are oviparous.
Therefore,the group consisting of Kangaroo,Dolphin,Rat,and Whale are all viviparous.

(D) The class $Mammalia$ is characterized by several unique features.
$1$. The presence of $mammary$ $glands$ (milk-producing glands) is the most defining characteristic of mammals,used for nourishing their young.
$2$. The $muscular$ $diaphragm$ is a unique structure found in all mammals that separates the thoracic cavity from the abdominal cavity and plays a crucial role in respiration.
$3$. While other features like viviparity or heterodont teeth are common,they have exceptions (e.g.,$Ornithorhynchus$ or platypus is oviparous).
$4$. Therefore,the presence of a muscular diaphragm and mammary glands are the universal characteristics of all mammals.

(D) Most mammals are viviparous,meaning they give birth to live young.
However,there is a small group of mammals known as monotremes that are oviparous,meaning they lay eggs.
The $Ornithorhynchus$ (Platypus) and $Tachyglossus$ (Echidna) are classic examples of oviparous mammals.
Therefore,the correct option is $D$.

(D) The class $Mammalia$ is characterized by the presence of mammary glands (milk-producing glands) in females,which are used to nourish their young ones. This is the most unique and defining feature of mammals. Other features include the presence of hair on the skin and two pairs of limbs.

(B) Elephants belong to the class $Mammalia$. Like all mammals,they possess a left-sided aortic arch (the systemic arch curves to the left). Therefore,the statement that the aortic arch turns to the right is incorrect. Elephants are homeothermic (warm-blooded) animals and possess well-developed pinnae (external ears) for thermoregulation.

(A) Mammals are characterized by the presence of mammary glands and are generally viviparous,meaning they give birth to young ones.
This is because the developing embryo is nourished within the maternal body through a specialized structure called the placenta,which allows for the exchange of nutrients and waste products.
Therefore,the assertion that mammals are viviparous is correct,and the reason provided correctly explains the biological basis for this characteristic.

(A) Mammals are generally viviparous,meaning they give birth to live young.
However,the $Platypus$ (Ornithorhynchus) is an oviparous mammal,meaning it lays eggs.
This makes it distinct from other mammals like kangaroos,whales,and bats,which are viviparous.
Therefore,the correct answer is $A$.

(C) The $Dolphin$ is a marine mammal that exhibits specific adaptations for an aquatic lifestyle, such as a streamlined body, flippers (modified limbs), and a blowhole for breathing. These features allow it to swim efficiently in water. In contrast, rats, kangaroos, and bats are primarily terrestrial or aerial animals.

(C) In mammals,the systemic aorta (aortic arch) curves to the left side of the heart. In birds (Aves),such as pigeons,crows,and peacocks,the systemic aorta curves to the right side. Since the dolphin is a mammal,its aortic arch curves to the left.

(D) In most mammals,mature red blood cells $(RBCs)$ lack a nucleus (enucleated) to provide more space for hemoglobin,which increases the oxygen-carrying capacity of the blood. Exceptions include camels and llamas,which possess nucleated $RBCs$. Other classes like $Chondrichthyes$,$Aves$,and $Reptilia$ possess nucleated $RBCs$ throughout their life.

(A) The $Bat$ (order $Chiroptera$) is the only mammal capable of true and sustained flight. While other mammals like flying squirrels can glide,they do not possess the anatomical adaptations for powered flight like bats do.

(B) Bats belong to the class $Mammalia$.
Key characteristics of mammals include the presence of mammary glands,hair on the skin,and being warm-blooded $(homeothermic)$.
Unlike birds,bats do not have air sacs connected to their lungs,nor do they have a gizzard or a beak.
Bats are the only mammals capable of true flight due to the presence of patagium (skin membranes) between their digits.

(A) The heart structure varies across different classes of vertebrates.
$1$. Frogs (Amphibians) have a $3$-chambered heart ($2$ atria and $1$ ventricle).
$2$. Snakes and Turtles (Reptiles) generally have a $3$-chambered heart,except for crocodiles which have a $4$-chambered heart.
$3$. Bats (Mammals) possess a $4$-chambered heart ($2$ atria and $2$ ventricles),which allows for complete separation of oxygenated and deoxygenated blood,supporting their high metabolic rate.

(B) Statement $A$ is true because most mammals are viviparous,meaning they give birth to young ones.
Statement $R$ is true because the presence of external ear pinnae is a characteristic feature of mammals.
However,the presence of external ear pinnae is not the reason why mammals are viviparous. Both are distinct diagnostic features of the class $Mammalia$. Therefore,$R$ is not the correct explanation of $A$.

(A) four-chambered heart is a characteristic feature of mammals,birds,and crocodiles.
Among the given options,the whale is a mammal.
Earthworms have a closed circulatory system with lateral hearts (pseudo-hearts) but not a four-chambered heart.
Sharks are cartilaginous fish and possess a two-chambered heart.
Salamanders are amphibians and possess a three-chambered heart.
Therefore,the correct answer is the whale.

(B) The duck-billed platypus (Ornithorhynchus anatinus) is a monotreme,which is a unique group of mammals.
$X$: Platypuses are oviparous (egg-laying) mammals,so statement $X$ is correct.
$Y$: While platypuses have a four-chambered heart,their aortic arch curves to the left,not the right. Therefore,statement $Y$ is incorrect.
$Z$: Platypuses possess mammary glands and hair,which are characteristic features of mammals,so statement $Z$ is correct.
Thus,$X$ and $Z$ are correct,while $Y$ is incorrect.

(B) The class $Mammalia$ is characterized by the presence of mammary glands in females.
These glands secrete milk,which is used to nourish the young ones.
This is a unique feature that distinguishes mammals from all other classes of vertebrates.

(D) Mammals are characterized by several unique features that distinguish them from other classes of vertebrates.
$1$. The presence of mammary glands is the most distinct feature,which is used for the nourishment of their young ones.
$2$. Hair on the skin or body is a unique characteristic of mammals.
$3$. The presence of an external ear or pinna is also a characteristic feature of mammals.
Since all these features are present in mammals,the correct answer is $D$.

(D) Mammals (Class $Mammalia$) are characterized by several unique features that distinguish them from other vertebrates.
$1$. The presence of hair on the skin is a unique characteristic of mammals.
$2$. The presence of an external ear or pinna is also a characteristic feature of most mammals.
$3$. Fins are characteristic of fish,not mammals.
Therefore,both the presence of pinna and hair on the body are defining characteristics of mammals.

(B) The presence of $Pinnae$ (external ears) is a unique and defining characteristic of mammals.
$Gills$ are respiratory organs typically found in fish and some amphibians.
$Fins$ are appendages used for swimming,primarily found in fish.
$Scales$ are typically found on the skin of reptiles and fish.
Therefore,the correct option is $B$.

(A) The presence of external ear pinnae (auricles) and hair on the skin are unique and diagnostic characteristics of the class $Mammalia$.
These features distinguish mammals from other vertebrate classes like $Aves$ (birds),$Reptilia$ (reptiles),and $Pisces$ (fishes).
Therefore,organisms possessing these traits belong to the group $Mammals$.

(B) The correct answer is $B$.
Whales,dolphins,and seals are classified as aquatic mammals because they are warm-blooded,breathe air through lungs,and give birth to live young.
Trygon (stingray) and sharks belong to the class Chondrichthyes,which are cartilaginous fishes,not mammals.

(A) : Viviparity is not a shared characteristic.
All birds are oviparous (egg-laying),whereas most mammals are viviparous (giving birth to young ones).
Exceptions among mammals include monotremes like $Ornithorhynchus$ (duck-billed platypus) and $Tachyglossus$ (spiny anteater),which are oviparous.
However,since the majority of mammals are viviparous and all birds are oviparous,viviparity is not a common trait shared by both groups.

(A) : Duck-billed platypus is an egg-laying mammal (oviparous).
It is found in the rivers of eastern Australia and Tasmania.
It is a beaver-like monotreme about $50-60 \ cm$ long and is well-adapted to live in water.
Usually,two eggs are laid at a time.
The female curls around them for incubation and remains inactive for about two weeks.
Newly hatched young ones are very immature,naked,blind,and each is $2.5 \ cm$ long.
In contrast,whales,bats,and elephants are placental mammals and are viviparous.

(A) The correct answer is $A$.
$1$. Kangaroo,hedgehog,dolphin,and Loris are all mammals that give birth to live young ones (viviparous).
$2$. Ostrich and kiwi are birds,which are oviparous (egg-laying).
$3$. Platypus is a monotreme,a primitive mammal that lays eggs.
$4$. Therefore,only the set in option $A$ consists entirely of viviparous mammals.

(B) Taxonomic hierarchy classifies organisms into various categories.
$Mammalia$ is a class within the phylum $Chordata$.
$Carnivora$ is an order belonging to the class $Mammalia$,which includes flesh-eating animals like cats,dogs,and bears.
$Sapindales$,$Poales$,and $Polemoniales$ are orders belonging to the class $Angiospermae$ (flowering plants).

(B) $Macropus$ (Kangaroo) is a member of the class $Mammalia$.
$Corvus$ (Crow) belongs to the class $Aves$.
$Alligator$ belongs to the class $Reptilia$.
$Chelone$ (Turtle) belongs to the class $Reptilia$.

(A) The correct match is $A$ (Oviparous - Ornithorhynchus).
$Ornithorhynchus$ (Platypus) is a monotreme,which is an egg-laying mammal (oviparous).
$Columba$ (Pigeon) is a bird,which is oviparous,not viviparous.
$Bufo$ (Toad) belongs to the class Amphibia and has moist,glandular skin without scales.
$Angel$ fish (Pterophyllum) is a bony fish; it does not have a tympanum (which is characteristic of tetrapods like amphibians and reptiles).

(D) Mammals are generally viviparous,meaning they give birth to live young.
However,there is a small group of mammals known as monotremes that lay eggs.
These are called oviparous mammals.
The $Ornithorhynchus$ (Platypus) and $Tachyglossus$ (Echidna) are the two primary examples of oviparous mammals.
Therefore,the correct option is $D$.

(D) Mammals are characterized by the presence of hair on their skin. However,in the order $Cetacea$ (which includes whales,dolphins,and porpoises),hair is either completely absent or reduced to a few sensory bristles around the mouth in adults. This is an adaptation to their fully aquatic lifestyle.

(B) Eutherians,also known as placental mammals,are characterized by the presence of a $True \ placenta$ (chorioallantoic placenta) which facilitates the exchange of nutrients,gases,and waste products between the mother and the developing fetus. This allows for a longer gestation period and more advanced development of the young before birth. Therefore,the correct option is $B$.

(B) Mammals are generally viviparous,meaning they give birth to live young. However,there is a small group of mammals known as monotremes that lay eggs. The $Ornithorhynchus$ (Platypus) and $Tachyglossus$ (Echidna) are examples of oviparous mammals. Therefore,the correct option is $B$.

(B) Whales,bats,and rats are all members of the class $Mammalia$.
One of the defining characteristics of mammals is the presence of a muscular diaphragm that separates the thoracic cavity from the abdominal cavity.
This structure plays a crucial role in respiration.
While some mammals have external ears (pinnae),not all do (e.g.,whales have internal ear openings).
Extra-abdominal testes are not a universal feature of all mammals (e.g.,in whales,testes are abdominal).
Therefore,the presence of a muscular diaphragm is the most accurate common feature among these organisms.

(C) Mammals are characterized by several unique features such as the presence of mammary glands,hair on the skin,and a diaphragm.
Regarding the given options:
$1$. Thecodont dentition (teeth embedded in sockets) is a characteristic feature of mammals.
$2$. Alveolar lungs are present in mammals for efficient gas exchange.
$3$. Mammals possess $12$ pairs of cranial nerves,not $10$. Amphibians and reptiles possess $10$ pairs of cranial nerves. Therefore,this is not a characteristic feature of mammals.
$4$. Most mammals have $7$ cervical vertebrae,regardless of the length of their neck.
Thus,the correct answer is $C$.

(C) Animals that give birth to young ones are known as viviparous mammals.
$A$. Platypus is an oviparous (egg-laying) mammal.
$B$. Sparrow and Kiwi are birds (oviparous).
$C$. Kangaroo (marsupial),Hedgehog (placental mammal),Dolphin (aquatic mammal),and Loris (primate) are all mammals that give birth to young ones.
$D$. Ostrich is a bird (oviparous).

(C) The correct grouping of aquatic animals is Whale,Dolphin,and Seal.
$1$. Whales and Dolphins are aquatic mammals belonging to the class $Mammalia$.
$2$. Seals are also aquatic mammals belonging to the class $Mammalia$.
$3$. Sharks and Trygon (stingray) are cartilaginous fishes belonging to the class $Chondrichthyes$.
$4$. Therefore,the group consisting of Whale,Dolphin,and Seal represents a consistent grouping of aquatic mammals.

(C) In almost all mammals,the number of cervical vertebrae is $7$. This is a characteristic feature of the class $Mammalia$. Whether it is a camel,a rabbit,a horse,or a whale,they all possess $7$ cervical vertebrae. Therefore,the number of cervical vertebrae in a camel is equal to that of a rabbit,a horse,and a whale. Among the given options,the statement that the number is the same as that of a whale is correct.