Animalia Questions in English

(N/A) The animal belongs to the phylum $Platyhelminthes$.
They are commonly called 'flatworms' because of their dorsoventrally flattened bodies.
One example is $Planaria$ (or $Fasciola$ / Liver fluke,or $Taenia$ / Tapeworm).

(N/A)

Similarities between nematodes and annelids	Differences between nematodes and annelids
$1.$ Both have a bilaterally symmetrical body.	$1.$ Annelids have a segmented body,whereas nematodes have a cylindrical body.
$2.$ Both have triploblastic germ layers.	$2.$ Annelids have a true body cavity (coelom),whereas nematodes have a pseudocoelom.

(N/A)

$BONY\, FISH$	$CARTILAGINOUS\, FISH$
$(i)$ Found in both freshwater and marine water.	$(i)$ Mostly found in marine water.
$(ii)$ Mouth is terminal in position.	$(ii)$ Mouth is usually ventral.
$(iii)$ Endoskeleton is made of bone.	$(iii)$ Endoskeleton is made of cartilage.
$(iv)$ Body is usually spindle-shaped. Examples: $Labeo$,$Anabas$.	$(iv)$ Body is dorsoventrally flattened. Examples: $Torpedo$,$Scoliodon$.

(N/A)

Non-chordates	Chordates
$(i)$ Notochord is absent.	$(i)$ Notochord is present.
$(ii)$ Central nervous system is solid and ventral.	$(ii)$ Central nervous system is hollow and dorsal.
$(iii)$ Pharyngeal gill slits are absent.	$(iii)$ Pharyngeal gill slits are present.
$(iv)$ Heart,if present,is dorsal.	$(iv)$ Heart is ventral.
$(v)$ Post-anal tail is absent.	$(v)$ Post-anal tail is present.

Detailed explanation:
$1$. In non-chordates,the notochord is completely absent throughout their life cycle.
$2$. The central nervous system in non-chordates is solid and located ventrally,whereas in chordates,it is hollow and located dorsally.
$3$. Chordates possess pharyngeal gill slits at some stage of their development,which are absent in non-chordates.
$4$. The heart in non-chordates is typically dorsal,while in chordates,it is located ventrally.
$5$. $A$ post-anal tail is a characteristic feature of chordates,which is absent in non-chordates.

(N/A) All chordates possess the following fundamental features:
$(i)$ Presence of a notochord.
$(ii)$ Presence of a dorsal hollow nerve cord.
$(iii)$ Presence of paired pharyngeal gill slits.
$(iv)$ Presence of a post-anal tail.
$(v)$ They are triploblastic,bilaterally symmetrical,and coelomate animals.

(N/A) The organism shown in the image is an octopus,which belongs to the phylum Mollusca.
Two characteristic features of the phylum Mollusca are:
$1$. They have a muscular foot used for locomotion.
$2$. They possess an open circulatory system and a reduced coelomic cavity.

(N/A) Scorpion: Coelomate (Phylum Arthropoda)
$(b)$ Sea anemone: Acoelomate (Phylum Cnidaria)
$(c)$ Ascaris: Pseudocoelomate (Phylum Aschelminthes)
$(d)$ Earthworm: Coelomate (Phylum Annelida)
$(e)$ Wuchereria: Pseudocoelomate (Phylum Aschelminthes)
$(f)$ Nereis: Coelomate (Phylum Annelida)

(N/A) $(i)$ Arthropoda: They possess jointed appendages and a chitinous exoskeleton.
$(ii)$ Amphibia: They are adapted to live both in water and on land,and they typically have moist,glandular skin without scales.
$(iii)$ Porifera: They are multicellular organisms with a body characterized by numerous pores (ostia) and a canal system for water circulation.

(N/A) $(i)$ Amphibians have a three-chambered heart,whereas fishes have a two-chambered heart.
$(ii)$ Amphibians respire through lungs on land,whereas fishes respire through gills.
$(b)$ $(i)$ Phylum Porifera.
$(ii)$ Phylum Echinodermata.
$(c)$ Gymnosperms do not require water for fertilization because they produce pollen grains that are transferred to the female reproductive organs by wind (anemophily),allowing the male gametes to reach the egg without the need for an external water medium.

(N/A) $(i)$ and $(ii)$ The diagram of Hydra with the required labels is provided in the reference image.
$(iii)$ Hydra belongs to the phylum Coelenterata,also known as Cnidaria.
$(iv)$ Corals are a well-known example of animals in this group that live in colonies.

(N/A) $(i)$ Nematodes are called pseudocoelomates because their body cavity is not fully lined by mesoderm; instead,the mesoderm is present as scattered pouches between the ectoderm and endoderm.
$(ii)$ Arthropods have an open circulatory system because their blood is pumped out of the heart into body cavities called sinuses or hemocoel,where it directly bathes the tissues and organs,rather than flowing through a closed network of vessels.
$(iii)$ Echinoderms are named so because they possess an endoskeleton of calcareous ossicles,which gives their body a spiny appearance (the term 'Echinodermata' is derived from Greek words meaning 'spiny skin').

(N/A) Mammals have mammary glands to produce milk for nourishing their young ones.
$(b)$ Annelids have a true body cavity (coelom) because they exhibit a high degree of organ differentiation and tissue organization,allowing for complex internal systems.
$(c)$ Fish possess gills to extract dissolved oxygen from water,which is essential for their respiration in an aquatic environment.

(A) The classification based on the presence of a true coelom is as follows:
$1$. $Spongilla$ (Porifera): Acoelomate (No body cavity).
$2$. $Planaria$ (Platyhelminthes): Acoelomate (No body cavity).
$3$. $Ascaris$ (Nematoda): Pseudocoelomate (False body cavity).
$4$. $Scorpion$ (Arthropoda): Coelomate (True body cavity).
$5$. $Birds$ (Chordata): Coelomate (True body cavity).
$6$. $Nereis$ (Annelida): Coelomate (True body cavity).
Therefore,$Spongilla$ and $Planaria$ are acoelomates,$Ascaris$ is a pseudocoelomate,and $Scorpion$,$Birds$,and $Nereis$ are coelomates.

(N/A) Echidna and Platypus are classified as mammals because they possess mammary glands to feed their young with milk,have hair on their bodies,and are warm-blooded (homeothermic),despite the fact that they lay eggs (oviparous).
$(b)$ Birds have pneumatic (hollow and air-filled) bones to reduce their body weight,which makes them light and facilitates flight.

(N/A) $(i)$ Tapeworms are endoparasites that live in the intestine of the host. They absorb pre-digested nutrients directly through their body surface,hence they do not require a digestive tract.
$(ii)$ Frogs exhibit cutaneous respiration through their moist skin while in water and pulmonary respiration through lungs while on land,allowing them to survive in both aquatic and terrestrial environments.
$(iii)$ $A$ whale is classified as a mammal because it is warm-blooded,gives birth to live young,possesses mammary glands to feed its offspring,and breathes air using lungs.

(N/A) Whales belong to the class $Mammalia$, while fishes belong to the class $Pisces$. Here are three distinguishing features:

$Whale$	$Fish$
$(i)$ It is a warm-blooded animal (homeothermic).	$(i)$ It is a cold-blooded animal (poikilothermic).
$(ii)$ It has a four-chambered heart.	$(ii)$ It has a two-chambered heart.
$(iii)$ It breathes through lungs.	$(iii)$ It breathes through gills.

(N/A) Platyhelminthes:
$(i)$ They are bilaterally symmetrical.
$(ii)$ They are triploblastic (three germ layers).
$(iii)$ They are dorsiventrally flattened (flatworms).
$(iv)$ They are acoelomate (no body cavity).
$(b)$ Nematoda:
$(i)$ They are bilaterally symmetrical.
$(ii)$ They are triploblastic.
$(iii)$ They possess a pseudocoelom (false body cavity).
$(iv)$ Their body is cylindrical and unsegmented.

(N/A) Nematoda: These organisms possess a pseudocoelom,which is a body cavity not completely lined by mesoderm.
$(b)$ Echinodermata: These animals possess a unique water vascular system (water-driven tube system) which helps in locomotion,capture,and transport of food and respiration.
$(c)$ Arthropoda: This phylum is characterized by the presence of jointed appendages (jointed legs).
$(d)$ Porifera: These are pore-bearing animals where the body wall contains numerous ostia (pores) leading to a water canal system for circulation.
$(e)$ Chordata (specifically Protochordata): These animals possess a notochord at some stage of their life cycle.

(N/A) Organisms belonging to phyla Platyhelminthes,Nematoda,and Annelida are triploblastic and exhibit bilateral symmetry.
$(b)$ Triploblastic body organisation refers to the presence of three germinal layers (ectoderm,mesoderm,and endoderm) in the developing embryo. Bilateral symmetry means that the body can be divided into identical left and right halves along a single plane.
$(c)$ Comparison based on coelom:
$1$. Platyhelminthes: Acoelomatic (lack a body cavity).
$2$. Nematoda: Pseudocoelomatic (have a false body cavity).
$3$. Annelida: Coelomatic (have a true body cavity lined by mesoderm).

(N/A) Feather star $(Antedon)$ possesses a water vascular system (tube system) used for locomotion and food capture. $Euplectella$ (Venus flower basket) possesses a canal system (syconoid type) that facilitates water circulation for nutrition and respiration.
$(b)$ The skeleton of a shark is cartilaginous,meaning it is composed entirely of cartilage. The skeleton of a sea horse is bony,composed of calcified plates.
$(c)$ Tadpoles are aquatic larvae that respire primarily through gills. Adult frogs are semi-terrestrial and respire through lungs,skin (cutaneous respiration),and the buccal cavity.
$(d)$ The forelimbs of birds are modified into wings for flight. The forelimbs of lizards are pentadactyl limbs adapted for crawling or walking on land.
$(e)$ The skin of a tree frog is moist,slimy,and contains mucus glands to facilitate cutaneous respiration. Human skin is dry,keratinized,and contains sweat glands for thermoregulation and excretion,along with hair follicles.

(N/A) The housefly belongs to the phylum $Arthropoda$ and the class $Insecta$.
Characteristic features of $Arthropoda$:
$1$. They are bilaterally symmetrical and their bodies are segmented.
$2$. They possess an open circulatory system.
$3$. They have a blood-filled coelomic cavity known as the $haemocoel$.
$4$. They possess jointed appendages (legs).
Examples of $Arthropoda$:
$Butterfly$,$scorpion$,$cockroach$,$centipede$,$spider$,and $prawn$.

(N/A) $(i)$ Pisces: They have an exoskeleton of scales,an endoskeleton of bone/cartilage,and they breathe through gills.
$(ii)$ Amphibia: They possess gills in the larval stage and lungs in most adults; they have slimy,glandular skin.
$(iii)$ Reptilia: They have an exoskeleton of scales and are cold-blooded animals that lay eggs outside water.
$(iv)$ Aves: They have an exoskeleton of feathers,and their forelimbs are modified into wings for flight.
$(v)$ Mammalia: They have an exoskeleton of hair,possess external ears (pinnae),and are mostly viviparous (giving birth to young ones).

(N/A) The five classes of vertebrates are: $Pisces$,$Amphibia$,$Reptilia$,$Aves$,and $Mammalia$.
Comparison between two classes (e.g.,$Pisces$ and $Mammalia$):

Basis of Comparison	$Pisces$	$Mammalia$
$(i)$ Habitat	Aquatic	Mainly terrestrial
$(ii)$ Skin Covering	Scales	Hair
$(iii)$ Respiratory Organs	Gills	Lungs
$(iv)$ Heart Chambers	$2$ chambers	$4$ chambers
$(v)$ Reproduction	Lay eggs in water	Give birth to young ones

(A) The notochord is a long,rod-like support structure (chord $=$ string) that runs along the back of the animal,separating the nervous tissue from the gut.
It provides a site for muscles to attach,which facilitates ease of movement.

(N/A) Crocodiles possess a four-chambered heart,yet they are classified as reptiles because they exhibit typical reptilian characteristics such as laying eggs with tough,leathery shells on land,which do not require water for development,unlike amphibians.

(N/A)

Porifera	Coelenterata
$(i)$ They exhibit cellular level of organization.	$(i)$ They exhibit tissue level of organization.
$(ii)$ Their body is diploblastic or lacks true tissue layers.	$(ii)$ Their body is distinctly diploblastic with two layers of cells.
$(iii)$ They possess numerous pores (ostia) all over the body for water circulation.	$(iii)$ They do not have pores all over the body; instead,they have a single opening called the hypostome.

(N/A) Tapeworms are endoparasites that live in the intestine of the host. They lack a digestive tract because they absorb pre-digested nutrients directly from the host's intestine through their body surface.
$(b)$ Frogs exhibit cutaneous respiration through their moist skin when submerged in water and pulmonary respiration using lungs when they are on land.
$(c)$ Birds possess pneumatic (hollow) bones to reduce their body weight,which is an essential adaptation for flight,allowing them to remain buoyant and fly efficiently.

(N/A) The two mammals that lay eggs are the $Echidna$ (spiny anteater) and the $Platypus$ (duck-billed platypus).
These egg-laying mammals,known as monotremes,serve as a connecting link between the class $Reptilia$ and the class $Mammalia$ because they possess characteristics of both groups (e.g.,laying eggs like reptiles but having mammary glands like mammals).
$A$ mammal that gives birth to poorly developed young ones is the $Kangaroo$ (a marsupial).

(N/A) The phylum is Echinodermata. These organisms possess a unique water vascular system (water-driven tube system) which is used for locomotion,capture and transport of food,and respiration.
$(b)$ The phylum is Mollusca. These organisms typically have a muscular foot used for locomotion and an open circulatory system (except for cephalopods).
$(c)$ The phylum is Porifera. These organisms are characterized by the presence of numerous pores (ostia) on their body,which lead to a canal system that facilitates water circulation for nutrition and gas exchange.

(N/A) $(i)$ Warm-blooded animals (Endotherms): These organisms can regulate their internal body temperature regardless of the external environment.
$(ii)$ Nematodes (Roundworms): These are organisms belonging to the phylum Nematoda,characterized by a body cavity that is not fully lined by mesoderm,known as a pseudocoelom.
$(iii)$ Gymnosperms: These are seed-producing plants where the seeds are not enclosed within an ovary or fruit,hence they are referred to as 'naked seeds'.

(D) The organisms described are sponges.
They belong to the phylum $Porifera$.
These organisms are characterized by the presence of numerous pores called $ostia$ all over their body,which lead into a central cavity known as the $spongocoel$.
This system,known as the $canal$ $system$ or $water$ $transport$ $system$,helps in circulating water throughout the body to bring in food,oxygen,and remove waste products.

(B) In an open circulatory system,blood is pumped out of the heart into body cavities (sinuses) where tissues are bathed in blood.
$(i)$ Arthropoda: Most arthropods (e.g.,insects,crustaceans) possess an open circulatory system.
$(ii)$ Mollusca: Most mollusks (except cephalopods like octopus) possess an open circulatory system.
$(iii)$ Annelida: Annelids (e.g.,earthworms) possess a closed circulatory system.
$(iv)$ Coelenterata: These organisms lack a specialized circulatory system; they rely on diffusion for transport.
Therefore,$(i)$ and $(ii)$ have an open circulatory system.

(C) The body cavity in $Arthropoda$ is known as the $haemocoel$.
In this group,the coelom is reduced and filled with blood,which is why their circulatory system is of the open type.
In $Annelida$,the coelom is a true coelom containing coelomic fluid.
In $Nematoda$,the body cavity is a pseudocoelom.
In $Echinodermata$,the coelom is present but is part of the water vascular system.

(A) The most fundamental and defining characteristic of the phylum $Chordata$,which includes vertebrates,is the presence of a $notochord$ at some stage of their life cycle.
In vertebrates,the $notochord$ is replaced by a cartilaginous or bony vertebral column in the adult stage.
While triploblastic condition,gill pouches,and coelom are also present in vertebrates,they are shared with many other invertebrate groups.
Therefore,the presence of a $notochord$ is the most distinct and defining feature that separates vertebrates from other animal groups.

(D) Scales are protective structures found on the skin of certain vertebrates.
$(i)$ Amphibians have moist,glandular skin without scales.
$(ii)$ Pisces (fishes) generally have scales covering their body.
$(iii)$ Reptiles have dry,cornified skin covered with scales.
$(iv)$ Mammals have skin covered with hair,not scales.
Therefore,both Pisces and Reptiles possess scales. The correct option is $(ii)$ and $(iii)$.

(A) The statement in option $A$ is false because while most fishes,amphibians,and reptiles are indeed oviparous,there are notable exceptions. For example,many sharks (like the Great White Shark) and some snakes (like the Viper) are ovoviviparous or viviparous. Therefore,the blanket statement that all fishes,amphibians,and reptiles are oviparous is scientifically incorrect.
$B$: $Aves$ (birds) are homeothermic (warm-blooded),oviparous,and possess a four-chambered heart. This is a correct statement.
$C$: $Aves$ are characterized by feathers,forelimbs modified into wings for flight,and respiration exclusively through lungs. This is a correct statement.
$D$: Most mammals are viviparous (give birth to young ones),with the exception of monotremes like the platypus and echidna. This is a correct statement.

(B) The phylum $Echinodermata$ is characterized by the presence of a unique water vascular system.
This system plays a vital role in locomotion,capture and transport of food,and respiration.
The locomotory organs associated with the water vascular system are known as $Tube$ $feet$ (or $podia$).
These structures are extensions of the water vascular system that help the organism move and adhere to surfaces.

(C) Corals belong to the phylum $Cnidaria$ (also known as $Coelenterata$).
They are marine invertebrates that typically live in compact colonies of many identical individual polyps.
These polyps secrete calcium carbonate to form a hard skeleton,which provides support and protection for the colony.
Therefore,corals are $Cnidarians$ that live in colonies.

(A) true fish belongs to the class $Pisces$ (or $Chondrichthyes$ and $Osteichthyes$ in modern classification),characterized by having gills,fins,and a backbone.
$Dogfish$ (also known as $Scoliodon$ or spiny dogfish) is a cartilaginous fish belonging to the class $Chondrichthyes$.
$Jellyfish$ is a cnidarian (invertebrate).
$Starfish$ is an echinoderm (invertebrate).
$Silverfish$ is an insect (arthropod).
Therefore,$Dogfish$ is the only true fish among the given options.

(B) The phylum $Echinodermata$ consists of organisms that are exclusively marine.
These animals are triploblastic and coelomate,possessing a unique water-vascular system that helps in locomotion,capture and transport of food,and respiration.
Examples include starfish $(Asterias)$,sea urchins $(Echinus)$,and sea cucumbers $(Cucumaria)$.
In contrast,$Porifera$,$Mollusca$,and $Pisces$ contain both marine and freshwater species.

(B) The class $Chondrichthyes$ (cartilaginous fishes) consists of organisms whose endoskeleton is entirely cartilaginous.
Sharks,rays,and skates belong to this class.
In contrast,$Tuna$ and $Rohu$ belong to the class $Osteichthyes$ (bony fishes),which possess a bony endoskeleton.
Therefore,the correct answer is $Sharks$.

(C) The phylum $Annelida$ includes segmented worms such as $Nereis$,earthworms $(Pheretima)$,and leeches $(Hirudinaria)$.
$Urchins$ (Sea urchins) belong to the phylum $Echinodermata$,characterized by a spiny skin and a water vascular system.
Therefore,$Urchins$ are not Annelids.

(A) The body cavity in animals of phylum $Arthropoda$ is filled with blood and is known as the $haemocoel$.
In these animals,the true coelom is reduced and the body cavity acts as a circulatory system,which is referred to as an open circulatory system.
Therefore,animals with a blood-filled coelomic cavity belong to phylum $Arthropoda$.

(B) In the animal kingdom,the class $Pisces$ (fishes) is characterized by having a two-chambered heart,consisting of one atrium and one ventricle.
This heart pumps deoxygenated blood to the gills for oxygenation,which then circulates to the rest of the body.
In contrast,$Amphibia$ and most $Reptilia$ have a three-chambered heart,while $Aves$ and mammals have a four-chambered heart.

(B) $Protochordata$ are a group of marine animals that possess a notochord at some stage of their life cycle.
They exhibit bilateral symmetry,are triploblastic,and possess a coelom.
They have a circulatory system.
However,jointed legs are a characteristic feature of the phylum $Arthropoda$,not $Protochordata$.
Therefore,the correct answer is $B$.

(C) The organisms belonging to the phylum $Coelenterata$ (also known as $Cnidaria$) exhibit tissue-level organization.
In this level of organization,cells performing the same function are arranged into tissues,but they do not form complex organs or organ systems.
In contrast,$Mollusca$,$Arthropoda$,and $Echinodermata$ exhibit organ-system level of organization,where specialized organs work together to perform complex physiological functions.

(D) The organisms belonging to the phylum $Echinodermata$ (e.g.,starfish,sea urchins) possess an endoskeleton composed of calcareous ossicles (calcium carbonate plates).
These structures provide support and protection to the soft body parts of the organism.
Therefore,hard calcium carbonate structures are used as a skeleton by $Echinodermata$.

(B) The phylum Porifera includes organisms commonly known as sponges.
$Spongilla$ is a well-known freshwater sponge belonging to the phylum Porifera.
$Euglena$ belongs to the kingdom Protista.
$Penicillium$ is a fungus.
$Hydra$ belongs to the phylum Cnidaria.

(C) The correct answer is $C$ (Filaria).
$1$. $Hydra$, $Jellyfish$, and $Corals$ are all aquatic organisms that live in water environments.
$2$. $Filaria$ (specifically $Wuchereria$ $bancrofti$) is a parasitic nematode that lives inside the human body, specifically in the lymphatic system, and is not an aquatic animal.

(D) Amphibians belong to the class $Amphibia$.
Key characteristics of amphibians include:
$1$. They have a $3$-chambered heart ($2$ atria and $1$ ventricle).
$2$. They respire through gills (in larval stages),lungs,or skin.
$3$. Their skin is moist and contains mucus glands to keep it hydrated.
$4$. Unlike reptiles,amphibians do not have scales on their skin.
Therefore,the correct answer is $D$.