Mix Examples - Animal Kingdom Questions in English

(C) Comb jellies belong to the phylum $Ctenophora$. They possess eight external rows of ciliated comb plates,which help in locomotion.
Jelly fishes belong to the phylum $Cnidaria$ (also known as $Coelenterata$). They are characterized by the presence of cnidoblasts or cnidocytes.

(C) Animals that possess both male and female reproductive organs in the same individual are termed monoecious,bisexual,or hermaphrodite.
$Spongilla$ (freshwater sponge),$Ctenoplana$ (a member of Ctenophora),and $Fasciola$ (liver fluke) are examples of monoecious organisms.
$Ascaris$ (roundworm) is dioecious (unisexual),meaning male and female reproductive organs are present in separate individuals.

(C) $Balanoglossus$ belongs to the phylum $Hemichordata$.
$Anopheles$ belongs to the phylum $Arthropoda$.
$Laccifer$ belongs to the phylum $Arthropoda$.
Both $Hemichordata$ and $Arthropoda$ possess an open circulatory system,without any exception.

$(B)$. Limulus is commonly known as King crab, which is a living fossil.
$(b)$. Ophiura is commonly known as Brittle star, belonging to Phylum Echinodermata.
$(c)$. Taenia is commonly known as Tapeworm, belonging to Phylum Platyhelminthes.
$(d)$. Meandrina is commonly known as Brain coral, belonging to Class Anthozoa, Phylum Cnidaria.
$(e)$. Dentalium is commonly known as Tusk shell, belonging to Class Scaphopoda, Phylum Mollusca.
Therefore, the correct matching is: $a(iv), b(v), c(ii), d(iii), e(i)$.

(A) Platyhelminthes are acoelomate,meaning they lack a body cavity lined with mesoderm.
In contrast,Annelids are true coelomates (schizocoelomates),which means they possess a body cavity that is completely lined by mesoderm.
Therefore,the primary difference regarding the body cavity is the absence of a coelom in Platyhelminthes compared to the presence of a true coelom in Annelids.

(D) The incorrect match is option $(D)$.
$1$. Millipede belongs to the class Diplopoda (Phylum Arthropoda). They are terrestrial and possess two pairs of jointed appendages on each body segment,respiring through tracheae. This is a correct match.
$2$. Nereis belongs to the class Polychaeta (Phylum Annelida). They possess numerous setae on lateral appendages called parapodia,which help in swimming. This is a correct match.
$3$. Taenia solium (Tapeworm) belongs to the class Cestoda (Phylum Platyhelminthes). Their body is covered with a thick cuticle,and they lack an alimentary canal as they absorb nutrients directly from the host's intestine. This is a correct match.
$4$. Ctenophores (Phylum Ctenophora) are radially symmetrical and lack cnidoblasts (which are characteristic of Cnidaria). Crucially,they do not have a polyp stage in their life cycle. Therefore,the statement that a polyp stage is present is incorrect.

(C) The correct matching sequence is:
$(a)$. Planula larva is the larval stage of $Obelia$ (Phylum Cnidaria).
$(b)$. Glochidium larva is the larval stage of $Mussel$ (Phylum Mollusca).
$(c)$. Nauplius larva is the larval stage of $Crab$ (Phylum Arthropoda).
$(d)$. Cysticercus larva is the larval stage of $Taenia$ $solium$ (Phylum Platyhelminthes).
Therefore,the correct sequence is $a(iii), b(i), c(ii), d(v)$.

(D) The incorrect statement is $D$.
Metagenesis refers to the alternation of generations between the polyp (asexual) and medusa (sexual) forms,which is observed in certain Cnidarians like Obelia.
$Hydra$ does not exhibit metagenesis because it lacks a medusa stage in its life cycle.

(B) Assertion is true: Annelids,arthropods,and molluscs are indeed protostomial coelomates,meaning the blastopore develops into the mouth during embryonic development.
Reason is also true: Members of these three phyla exhibit bilateral symmetry and possess a true coelom (eucoelomates).
However,the fact that they have bilateral symmetry and a true coelom does not explain why they are classified as protostomes. Therefore,the Reason is not the correct explanation for the Assertion.

(D) . Urinary bladder is generally absent in most fishes (except some lungfishes).
$b$. $Gambusia$ is a larvivorous fish that feeds on mosquito larvae and is used for biological control of malaria.
$c$. Ampullae of Lorenzini in dogfish $(Scoliodon)$ are electroreceptors,but they also function as thermoreceptors to detect temperature changes.
$d$. Electric organs found in fishes like $Torpedo$ are modified muscle tissues.
Since all the given statements are scientifically correct,the correct option is $d$.

(A) Circulatory patterns are of two types:
$1$. Open Circulatory Pathways: Present in arthropods and molluscs,in which the blood pumped by the heart passes through large vessels into open spaces of the body cavity called sinuses.
$2$. Closed Circulatory Pathways: Annelids and chordates have a closed circulatory system in which the blood pumped by the heart is always circulated through a closed network of blood vessels. This pattern is considered to be more advantageous as the flow of fluid can be more precisely regulated.

(C) Water acts as a medium for transportation in various organisms:
$1$. In Sponges $(I)$,the water transport system is known as the water canal system.
$2$. In Hydra $(II)$,the gastrovascular cavity serves for the circulation of water and nutrients.
$3$. In Starfish $(IV)$,the water vascular system (ambulacral system) is a characteristic feature used for locomotion,capture,and transport of food.
Therefore,the correct combination is $I, II$ and $IV$.

(C) living fossil is an extant taxon that closely resembles related species known only from the fossil record.
$Archaeopteryx$ is an extinct genus of bird-like dinosaurs that serves as a transitional fossil between non-avian feathered dinosaurs and modern birds.
Since $Archaeopteryx$ is extinct, it cannot be classified as a living fossil.
$Peripatus$, $King \text{ } crab$ $(Limulus)$, and $Sphenodon$ are all examples of living fossils.

(B) The correct matches are as follows:
$(a)$ Metamerism is a characteristic feature of the phylum Annelida $(iii)$.
$(b)$ Canal system (water transport system) is a characteristic feature of the phylum Porifera $(iv)$.
$(c)$ Comb plates are present in the phylum Ctenophora $(ii)$ to help in locomotion.
$(d)$ Cnidoblasts (stinging cells) are characteristic of the phylum Coelenterata (Cnidaria) $(i)$.
Therefore,the correct sequence is $(a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)$.

(D) Statement $(a)$ is incorrect because Metagenesis is observed in Cnidarians (e.g.,Obelia),not in Helminths.
Statement $(b)$ is correct because Echinoderms are triploblastic and coelomate animals.
Statement $(c)$ is correct because Round worms (Aschelminthes) exhibit organ-system level of body organization.
Statement $(d)$ is incorrect because comb plates in Ctenophores help in locomotion,not digestion.
Statement $(e)$ is correct because the water vascular system is a unique characteristic feature of Echinoderms.
Therefore,statements $(b), (c),$ and $(e)$ are correct.

(C) The correct matches are as follows:
$1$. $(a)$ Physalia is commonly known as the Portuguese Man of War.
$2$. $(b)$ Limulus is known as the King crab,which is a living fossil.
$3$. $(c)$ Ancylostoma is commonly known as the Hookworm.
$4$. $(d)$ Pinctada is commonly known as the Pearl oyster.
Therefore,the correct matching is $(a)-(ii), (b)-(iii), (c)-(iv), (d)-(i)$.
Thus,the correct option is $C$.

(A) Saurology is the scientific study of lizards.
Serpentology and Ophiology are terms used for the study of snakes.
Ornithology is the study of birds.

(C) Deuterostomes are animals in which the first opening to develop in the embryonic digestive tube is the anus,and the mouth is formed later.
Echinoderms and chordates exhibit a deuterostomic body plan.
In contrast,annelids,arthropods,and molluscs exhibit a protostomic body plan,where the mouth develops first from the blastopore.

(C) The correct matching is $C$. $Rana$ $tigrina$ (frog) belongs to the class Amphibia.
$1$. They lack exoskeletal elements (skin is moist and glandular).
$2$. They possess a dicondylic skull (having two occipital condyles).
$3$. They have eyelids to protect their eyes.
Analysis of other options:
- $A$. Chameleon is a reptile,but it has a monocondylic skull.
- $B$. Monotremes are oviparous (egg-laying),not viviparous.
- $D$. $Scoliodon$ (dogfish) exhibits internal fertilization,not external.

(C) The Assertion is incorrect because Piscean (fish) scales are of mesodermal origin,whereas reptilian scales are of epidermal origin.
The Reason is correct because the age of both fish and reptiles can be estimated by observing the lines of growth (annuli) present on their scales.

(N/A) The following table provides a comparative summary of the key characteristics of the various phyla within the Animal Kingdom:

Phylum	Level of Organisation	Symmetry	Coelom	Segmentation	Digestive System	Circulatory System	Respiratory System	Distinctive Features
Porifera	Cellular	Various	Absent	Absent	Absent	Absent	Absent	Body with pores and canals in walls
Coelenterata	Tissue	Radial	Absent	Absent	Incomplete	Absent	Absent	Cnidoblasts present
Ctenophora	Tissue	Radial	Absent	Absent	Incomplete	Absent	Absent	Comb plates for locomotion
Platyhelminthes	Organ and Organ System	Bilateral	Absent	Absent	Incomplete	Absent	Absent	Flat body,suckers
Aschelminthes	Organ System	Bilateral	Pseudocoelomate	Absent	Complete	Absent	Absent	Often worm-shaped,elongated
Annelida	Organ System	Bilateral	Coelomate	Present	Complete	Present	Present	Body segmentation like rings
Arthropoda	Organ System	Bilateral	Coelomate	Present	Complete	Present	Present	Exoskeleton of cuticle,joined appendages
Mollusca	Organ System	Bilateral	Coelomate	Absent	Complete	Present	Present	External skeleton of shell usually present
Echinodermata	Organ System	Radial (Adult)	Coelomate	Absent	Complete	Present	Present	Water vascular system
Hemichordata	Organ System	Bilateral	Coelomate	Absent	Complete	Present	Present	Worm-like with proboscis,collar,and trunk
Chordata	Organ System	Bilateral	Coelomate	Present	Complete	Present	Present	Notochord,dorsal hollow nerve cord,gill slits

(N/A) $\rightarrow$ Placoid scales are characteristic of cartilaginous fishes (Chondrichthyes),for example,$Scoliodon$ (Dogfish).
$\rightarrow$ Cycloid scales are characteristic of bony fishes (Osteichthyes),for example,$Labeo$ $rohita$ (Rohu).

(N/A) $1$. Animals with a chitinous exoskeleton: Arthropods possess a tough, chitinous exoskeleton. An example is the cockroach $(Periplaneta \text{ } americana)$.
$2$. Animals covered by a calcareous shell: Molluscs are typically covered by a hard, calcareous shell. An example is the apple snail $(Pila)$.

(N/A) Cold-blooded animal: Frog (Amphibian).
$(b)$ Warm-blooded animal: Pigeon (Aves).
$(c)$ Animal possessing dry and cornified skin: Snake (Reptile).
$(d)$ Dioecious animal: Ascaris (Roundworm).

(N/A) Roundworm: $Ascaris$
$(b)$ Fish possessing poison sting: $Trygon$ (Sting ray)
$(c)$ $A$ limbless amphibian: $Ichthyophis$
$(d)$ An oviparous mammal: $Ornithorhynchus$ (Platypus)

(N/A) Haemocoel: The body cavity of arthropods is filled with blood,known as haemocoel.
$(b)$ Medusa: It is the free-swimming,umbrella-shaped form of cnidarians,such as jellyfish.
$(c)$ Nematocysts: These are specialized stinging cells (cnidoblasts) containing a coiled thread used for defense and prey capture.
$(d)$ Parapodia: These are lateral,fleshy,paddle-like appendages found in aquatic annelids like Nereis,which help in swimming.

(A) The correct matches are as follows:
$(1)$ Octopus: These mollusks use $(iii)$ Tentacles for movement.
$(2)$ Crocodile: These reptiles use $(i)$ Limbs for locomotion.
$(3)$ Catla: This is a bony fish that uses $(iv)$ Fins for swimming.
$(4)$ Ctenoplana: This ctenophore uses $(ii)$ Comb plates for locomotion.
Therefore,the correct sequence is $(1)-(iii), (2)-(i), (3)-(iv), (4)-(ii)$.

(N/A) The completed table is as follows:

Phylum/Class	Excretory organ	Circulatory system	Respiratory organ
Arthropoda	Malpighian tubules	Open	Lungs/Gills/Tracheal system
Annelida	Nephridia	Closed	Skin/Parapodia
Mollusca	Metanephridia	Open	Gills (Ctenidia)
Amphibia	Mesonephric kidneys	Closed	Lung

Explanation:
$1$. In $Arthropoda$,excretion occurs via $Malpighian$ $tubules$ and the circulatory system is $open$.
$2$. $Annelida$ are characterized by $Nephridia$ for excretion,a $closed$ circulatory system,and respiration through $skin$ or $parapodia$.
$3$. $Mollusca$ possess $metanephridia$ for excretion,an $open$ circulatory system,and respiration primarily through $gills$ $(ctenidia)$.
$4$. $Amphibia$ utilize $mesonephric$ $kidneys$ for excretion,have a $closed$ circulatory system,and use $lungs$ for respiration.

(D) The first organism shown is a tapeworm (Taenia),which belongs to the phylum Platyhelminthes. Organisms in this phylum have an incomplete digestive system (a single opening for both ingestion and egestion).
The second organism shown is a scorpion,which belongs to the phylum Arthropoda. Organisms in this phylum have a complete digestive system (two separate openings for ingestion and egestion).
Therefore,the correct sequence is Incomplete and Complete.

(D) The explanation for diploblastic animals is as follows:
$1$. Diploblastic organization is found in animals of the phyla Ctenophora and Cnidaria (Coelenterata),so option $A$ is correct.
$2$. In these animals,an undifferentiated layer exists between the ectoderm and endoderm,which is called mesoglea,so option $B$ is correct.
$3$. In diploblastic animals,cells are organized into tissues,thus they exhibit tissue-level organization,so option $C$ is also correct.
$4$. The question asks for the 'incorrect' statement. Since all given options are correct,the correct answer is option $D$.

(D) Metamerism or true segmentation is a characteristic feature where the body is externally and internally divided into segments with a serial repetition of at least some organs.
This phenomenon is observed in the phyla $Annelida$ (e.g.,earthworms),$Arthropoda$ (e.g.,insects),and $Chordata$ (e.g.,humans,where the vertebral column and muscles show metameric arrangement).
Therefore,all the given options exhibit metamerism.

(D) Metamerism is a phenomenon where the body is externally and internally divided into segments with a serial repetition of at least some organs.
Organisms exhibiting metamerism (e.g.,Annelida,Arthropoda,Chordata) are triploblastic,coelomate,and exhibit bilateral symmetry.
While Annelids possess a closed circulatory system,Arthropods possess an open circulatory system.
Therefore,the statement that organisms with metamerism possess a closed circulatory system is not universally true.
However,the most fundamentally incorrect statement among the options is that they exhibit radial symmetry,as all metameric animals exhibit bilateral symmetry.

(B) $1$. Porifera: Cellular level of organization,asymmetrical.
$2$. Coelenterata (Cnidaria): Diploblastic,tissue-level of organization.
$3$. Ctenophora: Diploblastic,tissue-level of organization.
$4$. Platyhelminthes: Triploblastic,organ-level of organization.
$5$. Aschelminthes: Triploblastic,organ-system level of organization.
Only Coelenterata and Ctenophora exhibit both diploblastic and tissue-level organization. Therefore,the total count is $2$.

(A) Flatworms belong to the phylum $Platyhelminthes$ because their body is dorsoventrally flattened.
Roundworms belong to the phylum $Aschelminthes$ (also known as $Nematoda$) because their body is circular in cross-section.
Therefore,flatworms and roundworms are respectively called $Platyhelminthes$ and $Aschelminthes$.

(D) In the phylum $Annelida$, organisms can be either unisexual or bisexual.
$Nereis$ is an aquatic form which is dioecious (unisexual), meaning male and female reproductive organs are present in separate individuals.
Earthworms $(Pheretima)$ and leeches $(Hirudinaria)$ are monoecious (bisexual or hermaphrodite), meaning both male and female reproductive organs are present in the same individual.
Therefore, the correct classification is: Unisexual organisms $(Nereis)$ and Bisexual organisms $(Earthworm, Leech)$.

(B) The image on the left shows a Leech (Hirudinaria),which belongs to the phylum Annelida.
The image on the right shows a Prawn (Palaemon),which belongs to the phylum Arthropoda.
Therefore,the correct identification is Leech and Prawn.

(D) To determine the correct count,let us analyze each animal:
$1$. Sepia (Mollusca): Bilateral,triploblastic,coelomate.
$2$. Loligo (Mollusca): Bilateral,triploblastic,coelomate.
$3$. Sea anemone (Cnidaria): Radial symmetry,diploblastic,acoelomate.
$4$. Balanoglossus (Hemichordata): Bilateral,triploblastic,coelomate.
$5$. Dentalium (Mollusca): Bilateral,triploblastic,coelomate.
$6$. Sea lily (Echinodermata): Radial symmetry (adults),triploblastic,coelomate.
$7$. Chiton (Mollusca): Bilateral,triploblastic,coelomate.
$8$. Pearl oyster (Mollusca): Bilateral,triploblastic,coelomate.
$9$. Starfish (Echinodermata): Radial symmetry (adults),triploblastic,coelomate.
The animals that are bilateral,triploblastic,and coelomate are: Sepia,Loligo,Balanoglossus,Dentalium,Chiton,and Pearl oyster.
Total count = $6$.

(A) In the phylum $Mollusca$, excretion is primarily carried out by specialized structures known as kidneys or metanephridia (often referred to as gills or ctenidia in some contexts for respiration, but the excretory organs are metanephridia). However, in the context of standard biology questions regarding these phyla, the excretory organ in $Mollusca$ is often associated with the mantle cavity/kidneys, while in $Hemichordata$, the specific excretory organ is the $Proboscis$ \text{ gland}. Given the options provided, the most accurate pairing for excretory structures is $Gills$ (often associated with the mantle cavity where excretory products are released) and $Proboscis$ \text{ gland} for $Hemichordata$.

(D) According to the classification of Vertebrata:
$1$. $P$ represents the Subphylum (Vertebrata is a subphylum of Chordata,but in this specific chart context,it divides into Agnatha and Gnathostomata,which are divisions).
$2$. $Q$ represents the Class Cyclostomata (under Agnatha).
$3$. $R$ represents the Classes Chondrichthyes and Osteichthyes (under the Superclass Pisces).
Therefore,$P$ is Division,$Q$ is Class,and $R$ is Class.

(A) Chondrichthyes (Cartilaginous fishes) characteristics:
- $I$: Air bladder is absent (they have to swim constantly to avoid sinking).
- $II$: Operculum (gill cover) is absent.
- $IV$: Placoid scales are present.
- $V$: Mouth is located ventrally.
- $VII$: Internal fertilization occurs.
Thus,the set is $(I, II, IV, V, VII)$.
Osteichthyes (Bony fishes) characteristics:
- $III$: Cycloid or ctenoid scales are present.
- $VI$: Mouth is mostly terminal.
- $VIII$: External fertilization occurs.
Thus,the set is $(III, VI, VIII)$.
Therefore,the correct option is $A$.

(D) Cold-blooded or poikilothermic animals are those that cannot regulate their internal body temperature and it fluctuates with the environment.
$1$. Cyclostomata (jawless fishes) are ectothermic.
$2$. Chondrichthyes (cartilaginous fishes) are ectothermic.
$3$. Osteichthyes (bony fishes) are also ectothermic.
Therefore,all the groups mentioned above are cold-blooded.

(D) two-chambered heart,consisting of one atrium and one ventricle,is a characteristic feature of fishes.
$Cyclostomata$ (jawless fishes),$Chondrichthyes$ (cartilaginous fishes),and $Osteichthyes$ (bony fishes) all belong to the superclass $Pisces$.
Therefore,all the organisms listed possess a two-chambered heart.

(C) Let us analyze the characteristics for both Amphibians and Reptiles:
$a$ - Type of fertilization: Amphibians usually show external fertilization,while Reptiles show internal fertilization. (Not common)
$b$ - Cold-blooded: Both are poikilothermic (ectothermic). (Common)
$c$ - Development: Both show indirect development (larval stages in amphibians,though some reptiles have direct development). (Not strictly common)
$d$ - Oviparous: Both are oviparous. (Common)
$e$ - Coelomate: Both are true coelomates. (Common)
$f$ - Bilateral symmetry: Both exhibit bilateral symmetry. (Common)
The common characteristics are $b, d, e,$ and $f$. Therefore,there are $4$ common characteristics.

(C) The correct scientific names (Genus) for the given animals are as follows:
$P$. Crow: $Corvus$ $(VI)$
$Q$. Pigeon: $Columba$ $(I)$
$R$. Parrot: $Psittacula$ $(III)$
$S$. Ostrich: $Struthio$ $(VII)$
$T$. Peacock: $Pavo$ $(II)$
$U$. Penguin: $Aptenodytes$ $(V)$
$V$. Vulture: $Neophron$ $(IV)$
Therefore,the correct matching is $(P-VI), (Q-I), (R-III), (S-VII), (T-II), (U-V), (V-IV)$.

(C) Homeothermic (warm-blooded) animals are those that maintain a constant body temperature regardless of the environment. In the given list,mammals and birds are homeothermic.
$1$. $Rattus$ (Rat) - Mammal (Homeothermic)
$2$. $Macropus$ (Kangaroo) - Mammal (Homeothermic)
$3$. $Balaenoptera$ (Blue whale) - Mammal (Homeothermic)
$4$. $Columba$ (Pigeon) - Bird (Homeothermic)
$5$. $Calotes$ (Garden lizard) - Reptile (Poikilothermic)
$6$. $Crocodilus$ (Crocodile) - Reptile (Poikilothermic)
$7$. $Naja$ (Cobra) - Reptile (Poikilothermic)
$8$. $Hyla$ (Tree frog) - Amphibian (Poikilothermic)
$9$. $Rana$ (Frog) - Amphibian (Poikilothermic)
$10$. $Neophron$ (Vulture) - Bird (Homeothermic)
$11$. $Tigris$ (Tiger) - Mammal (Homeothermic)
The homeothermic animals are: $Rattus, Macropus, Balaenoptera, Columba, Neophron, Tigris$.
Total count = $6$.

(A) Aves and Mammals share several characteristics:
$1$. Both are homeothermic (warm-blooded) $(I)$.
$2$. Both respire through lungs $(II)$.
$3$. Both have a four-chambered heart $(III)$.
$4$. Both are dioecious $(IV)$ and exhibit internal fertilization $(VI)$.
However,they differ in the following:
- Mammals possess hair on the skin $(V)$,whereas birds have feathers.
- Mammals typically possess teeth $(VII)$ (thecodont dentition),whereas birds lack teeth and have a beak instead.
Therefore,the characteristics $V$ and $VII$ are not common to both.

(B) $1$. Vertebrates are animals that possess a vertebral column or backbone. Among the given options, the frog (an amphibian) is a vertebrate.
$2$. Invertebrates are animals that lack a vertebral column. Earthworms (Annelida) and cockroaches (Arthropoda) are invertebrates.
$3$. Therefore, the correct classification is: Vertebrate $(Frog)$ and Invertebrates $(Earthworm, Cockroach)$.
$4$. This matches option $B$.

(C) In an open circulatory system,the blood is pumped out of the heart into sinuses or body cavities (haemocoel). This is found in Arthropoda and most Mollusca (except Cephalopods).
In a closed circulatory system,the blood is circulated through a series of vessels of varying diameters (arteries,veins,and capillaries). This is found in Annelida and Chordata.
Therefore,the correct classification is: Open circulatory system - Arthropoda,Mollusca; Closed circulatory system - Annelida,Chordata.

(D) The correct matching is as follows:
$A$. $Taenia$ (Platyhelminthes) uses flame cells $(III)$ for excretion.
$B$. $Paramoecium$ uses contractile vacuoles $(II)$ for osmoregulation and excretion.
$C$. $Periplaneta$ (Cockroach) uses urecose glands $(IV)$ for excretion.
$D$. $Pheretima$ (Earthworm) uses nephridia $(I)$ for excretion.
Therefore, the correct sequence is $A-III, B-II, C-IV, D-I$.

(A) The correct matching is as follows:
$A$. Pleurobrachia: It belongs to the phylum $Ctenophora$.
$B$. Radula: It is a file-like rasping organ for feeding found in the phylum $Mollusca$.
$C$. Stomochord: It is a rudimentary structure similar to the notochord found in the collar region of the phylum $Hemichordata$.
$D$. Air bladder: It is a gas-filled sac found in $Osteichthyes$ (bony fishes) that helps in regulating buoyancy.
Therefore, the correct sequence is $A-II, B-I, C-IV, D-III$.