Phylum-Arthropoda Questions in English

(D) In $Arthropoda$ and $Mollusca$,the true coelom is reduced.
The blood-filled spaces between the viscera merge to form a large cavity called the haemocoel.
$Scolopendra$ belongs to the phylum $Arthropoda$ (class $Myriapoda$),which is characterized by the presence of a haemocoel.
$Hydra$ is a $Cnidarian$,$Earthworm$ and $Nereis$ are $Annelids$ (which possess a true coelom).

(A) The body of members belonging to the phylum $Arthropoda$ is generally divided into three regions: head,thorax,and abdomen.
In many species,the head and thorax fuse together to form a single structure known as the cephalothorax.
Therefore,cephalothorax is a characteristic feature found in $Arthropoda$.

(C) The hepatopancreas is a digestive gland found in crustaceans,which belong to the phylum $Arthropoda$.
It performs the combined functions of the liver,intestine,and pancreas,such as the secretion of digestive enzymes and the absorption of nutrients.
Therefore,the presence of a hepatopancreas is a characteristic feature of arthropods.

(C) The term 'Hexapoda' is another name for the class $Insecta$.
This name is derived from the Greek words 'hexa' meaning $6$ and 'poda' meaning feet.
Members of this class are characterized by having $3$ pairs of jointed legs attached to the thoracic region of their body.

(C) The glow-worm and fireflies belong to the insect order $Coleoptera$.
$Lampyris noctiluca$ is the common European glow-worm, which is a type of beetle belonging to the class $Insecta$ of the phylum $Arthropoda$.

(A) The cockroach belongs to the phylum $Arthropoda$ and the class $Insecta$,which is also known as $Hexapoda$.
This class is characterized by the presence of three pairs of jointed legs,which is why they are called $Hexapoda$ (hexa = six,poda = feet).
$Apoda$ refers to limbless amphibians,$Myriapoda$ includes centipedes and millipedes,and $Cephalopoda$ refers to a class of mollusks like squids and octopuses.

(C) Silver fish,scorpion,crab,and honey bee all belong to the phylum $Arthropoda$. The most characteristic feature of all members of the phylum $Arthropoda$ is the presence of jointed appendages (jointed legs).

(A) In the biological classification,both moths and butterflies belong to the same order,$Lepidoptera$.
Historically,this order was divided into two sub-groups: $Heterocera$ (moths) and $Rhopalocera$ (butterflies).
Due to their shared evolutionary lineage and morphological similarities,moths are most closely related to butterflies.

(B) The $Nauplius$ larva is the characteristic first larval stage of many crustaceans,including shrimps,prawns,and copepods.
It is a free-swimming larva with three pairs of appendages.
Therefore,the $Nauplius$ larva belongs to the group of crustaceans,which includes shrimps.

(A) $Arthropoda$ is the largest phylum in the animal kingdom.
It includes approximately $80$ % of all known animal species.
This phylum consists of over $9,00,000$ described species,making it the most diverse group.

(D) The correct answer is $D$. Arthropods possess a true coelom (though reduced),a chitinous exoskeleton,and a body cavity filled with blood known as a haemocoel. $A$ $Malpighian$ body (also known as a renal corpuscle) is a structure found in the kidneys of higher vertebrates (chordates),consisting of a glomerulus and a Bowman's capsule. Arthropods possess $Malpighian$ tubules for excretion,which are entirely different structures.

(C) The correct answer is $C$. Insects belong to the phylum $Arthropoda$,which is characterized by an open circulatory system. In this system,the blood (hemolymph) does not flow through a closed network of arteries and veins. Instead,it is pumped by the heart into body cavities called sinuses or lacunae,where it bathes the tissues directly before returning to the heart.

(B) - Biramous appendages are characteristic of crustaceans (e.g.,$Prawn$).
These appendages consist of a basal protopodite that branches into two rami: an inner endopodite and an outer exopodite.

(B) . Termites are social insects that belong to the class $Insecta$ of the phylum $Arthropoda$.
$A$. $Octopus$ belongs to the phylum $Mollusca$.
$C$. $Nereis$ belongs to the phylum $Annelida$.
$D$. $Leech$ belongs to the phylum $Annelida$.

(B) The life cycle of a butterfly involves complete metamorphosis,which includes four stages: egg,larva,pupa,and adult.
$1$. The larva of a butterfly is known as a caterpillar.
$2$. The pupa stage of a butterfly is specifically referred to as a chrysalis.
$3$. The adult butterfly is known as the imago.
$4$. Therefore,the correct term for the pupa of a butterfly is chrysalis.

(A) Spiders and scorpions belong to the phylum $Arthropoda$ and the class $Arachnida$.
Members of the class $Arachnida$ are characterized by having four pairs of walking legs and a body divided into two main regions: the $cephalothorax$ and the $abdomen$.

(C) The correct answer is $C$.
In $Arachnids$ (such as spiders and scorpions),respiration occurs through specialized respiratory structures known as book-lungs.
These organs consist of a series of thin,leaf-like folds of tissue arranged like the pages of a book,which are connected to the outside environment through openings called spiracles or stigmata.

(C) In insects,the body cavity is filled with blood and is known as the haemocoel.
This cavity is not a true coelom because it is not lined by mesodermal epithelium.
Instead,it is a persistent blastocoel that develops during embryonic development.
Therefore,the haemocoel is considered a body cavity that is not a true coelom,and it is distinct from pseudocoelom or schizocoelom.

(C) Moths and butterflies belong to the insect order $Lepidoptera$. This order is characterized by insects having wings covered with tiny,overlapping scales.

(D) The correct answer is $D$.
$A$,$B$,and $C$ are members of the class $Insecta$ (phylum $Arthropoda$),which are characterized by having three pairs of jointed legs and a body divided into head,thorax,and abdomen.
$D$ (Spider) belongs to the class $Arachnida$. Spiders have four pairs of jointed legs and their body is divided into cephalothorax and abdomen,distinguishing them from true insects.

(B) The correct answer is $B$.
$A$ $Cockroach$, $C$ $Beetle$, and $D$ $Wasp$ are members of the class $Insecta$ (phylum $Arthropoda$), characterized by having three pairs of jointed legs.
$B$ $Tick$ belongs to the class $Arachnida$, which typically has four pairs of legs and lacks antennae.

(C) Cockroach,Anopheles (mosquito),and housefly all belong to the phylum $Arthropoda$ and the class $Insecta$.
Key characteristics of insects include having a body divided into head,thorax,and abdomen,and possessing three pairs of jointed legs (six legs in total).
Therefore,the presence of three pairs of legs is a common feature among these organisms.

(A) Crayfish belongs to the phylum $Arthropoda$ and the subphylum $Crustacea$.
Although they are often called 'fish',they are actually freshwater crustaceans that resemble small lobsters.
Therefore,the correct classification is that it is a crustacean animal.

(A) The phylum $Arthropoda$ is named after its most distinctive feature,which is the presence of jointed appendages ($arthros$ = joint,$poda$ = foot). These jointed legs allow for efficient movement and are a defining characteristic of all members of this phylum.

(C) The class $Insecta$ (under the phylum $Arthropoda$) contains the largest number of animal species on Earth. It is estimated to have approximately $7,75,000$ described species,which is more than all other animal groups combined.

(B) The characteristics mentioned are:
$1$. Segmented body: The body is divided into head,thorax,and abdomen.
$2$. Exoskeleton of chitinous cuticle: This provides protection and support.
$3$. Haemocoel: The body cavity is filled with blood,which is a characteristic feature of the phylum $Arthropoda$.
Therefore,these features collectively define the phylum $Arthropoda$.

(D) haemocoel is a body cavity filled with blood,which is a characteristic feature of the phylum $Arthropoda$ and $Mollusca$.
Among the given options:
- Earthworm $(Annelida)$ has a true coelom.
- Hydra $(Cnidaria)$ has a gastrovascular cavity.
- Sponge $(Porifera)$ lacks a body cavity.
- Scolopendra $(Arthropoda)$ possesses an open circulatory system where the body cavity is modified into a haemocoel.
Therefore,$Scolopendra$ is the correct choice.

(B) The characteristics mentioned are:
$1$. Bilateral symmetry: The body can be divided into two identical left and right halves.
$2$. Metameric segmentation: The body is divided into segments.
$3$. Coelom: They are coelomate animals.
$4$. Open circulatory system: Blood flows through open spaces called sinuses.
These features are diagnostic of the phylum $Arthropoda$. While $Annelida$ also shows metameric segmentation,they typically possess a closed circulatory system. $Mollusca$ are generally not metamerically segmented,and $Echinodermata$ exhibit radial symmetry in adults.

(A) Insects belong to the class $Insecta$ (or $Hexapoda$) and are characterized by having $3$ pairs of jointed legs (total $6$ legs) and usually $2$ pairs of wings.
Spiders belong to the class $Arachnida$ and are characterized by having $4$ pairs of jointed legs (total $8$ legs) and they never possess wings.
Therefore,an insect differs from a spider by having $3$ pairs of legs and $2$ pairs of wings,whereas a spider has $4$ pairs of legs and no wings.

(B) Complete metamorphosis involves four distinct stages: egg,larva,pupa,and adult.
Among the given options,the Gypsy Moth $(Lymantria dispar)$ belongs to the order Lepidoptera,which undergoes complete metamorphosis.
Silverfish exhibit ametabolism (no metamorphosis).
Bed bugs and grasshoppers exhibit incomplete metamorphosis (hemimetabolism),where the young (nymphs) resemble the adults.

(C) The eggs of $Anopheles$ mosquitoes are laid singly on the surface of the water.
These eggs possess lateral structures known as air floats or floats,which are filled with air.
These air floats provide buoyancy,allowing the eggs to remain afloat on the water surface.

(C) The life cycle of a housefly $(Musca \text{ } domestica)$ includes four stages: egg, larva, pupa, and adult. The larval stage, commonly known as a maggot, typically develops and lives in decaying organic matter such as dung, garbage, or decomposing plant material.

(C) Insects undergo metamorphosis,which can be complete (holometabolous) or incomplete (hemimetabolous).
Complete metamorphosis involves four stages: egg,larva,pupa,and adult. Mosquitoes,silk moths,and butterflies all undergo complete metamorphosis.
Incomplete metamorphosis involves three stages: egg,nymph,and adult,lacking a pupa stage. Bed bugs ($Cimex$ $lectularius$) undergo incomplete metamorphosis and therefore do not have a pupa stage.

(D) Ecdysis or moulting is the process of shedding or casting off the dead,rigid outer exoskeleton of an animal's body during its growth phase. $A$ new,larger,and more flexible covering is formed underneath to accommodate the animal's increasing size.

(B) The class $Insecta$ (or $Insecta$) is characterized by the presence of three pairs of jointed legs and a body divided into head,thorax,and abdomen.
$Julus$ belongs to the class $Diplopoda$ (millipedes).
Silver fish ($Lepisma$ $saccharina$) is a wingless insect belonging to the class $Insecta$.
Lobsters and Prawns belong to the class $Crustacea$ under the phylum $Arthropoda$.
Therefore,the correct answer is Silver fish.

(D) Both the housefly $(Musca \text{ } domestica)$ and the honey bee $(Apis \text{ } sp.)$ belong to the phylum $Arthropoda$ and the class $Insecta$.
Key characteristics of insects include a body divided into three regions (head, thorax, and abdomen) and the presence of three pairs of jointed legs attached to the thorax.
While they differ in their mouthparts and specific anatomical structures, the presence of three pairs of jointed legs is a diagnostic feature shared by all members of the class $Insecta$.

(B) $Anopheles$ and $Culex$ mosquitoes can be easily distinguished by their resting or sitting posture.
$Anopheles$ mosquitoes sit at an angle to the surface,appearing as if they are standing on their heads.
In contrast,$Culex$ mosquitoes sit parallel to the surface,keeping their bodies horizontal.

(C) Among the given options, the $Crab$ is non-poisonous.
$Scorpions$ possess a venomous sting in their telson.
$Centipedes$ have modified legs called forcipules that deliver venom to paralyze prey.
Most $Spiders$ possess venom glands used to immobilize their prey.
$Crabs$ are crustaceans and do not possess venom glands or stingers to inject toxins into other organisms.

(D) Tracheates are arthropods that respire through a system of air tubes called tracheae.
$1$. King Crabs (Limulus) are chelicerates that respire via book gills,not tracheae.
$2$. Crabs are crustaceans that primarily respire via gills.
$3$. Peripatus is an onychophoran that respires via tracheae,but the group in option $C$ is mixed with other classes.
$4$. Bed bugs,sandflies,and silkworms are all insects (Class Insecta) that possess a well-developed tracheal system for respiration.
Therefore,the group consisting of Bed Bug,Sandfly,and Silkworm is the correct tracheate group.

(C) The fly (order Diptera),mosquito (order Diptera),and cockroach (order Blattodea) all belong to the phylum Arthropoda and the class Insecta.
Class Insecta is characterized by having three pairs of jointed legs and usually two pairs of wings (though some may be modified or reduced).
While the cockroach has a $13$-chambered heart,flies and mosquitoes do not.
Therefore,the most common feature among these three organisms is their classification under the class Insecta.

(C) The sandfly belongs to the genus $Phlebotomus$.
These insects are known vectors for various diseases,such as leishmaniasis.
$Ancylostoma$ refers to hookworms,$Musca$ refers to the housefly,and $Drosophila$ is the common fruit fly.

(C) The phylum $Arthropoda$ is characterized by an open circulatory system,meaning the blood flows through body cavities called hemocoels rather than being confined within blood vessels. Therefore,a closed blood vascular system is absent in $Arthropoda$. Compound eyes,a chitinous exoskeleton,and Malpighian tubules are all characteristic features of this phylum.

(C) Swarming is a characteristic behavior observed in $Locusts$ (e.g.,$Schistocerca$ $gregaria$).
$Locusts$ are herbivorous insects that exhibit a gregarious phase,where they aggregate and migrate in massive numbers,causing significant damage to crops.
This phenomenon of moving in large groups is known as swarming.

(A) Insects belong to the phylum $Arthropoda$. The key characteristics of $Arthropoda$ include jointed appendages,a chitinous exoskeleton,and a haemocoel.
Option $A$ is incorrect because insects possess jointed appendages,not unjointed ones.
Option $B$ is correct as they have a chitinous exoskeleton and most possess wings.
Option $C$ is correct as they exhibit cephalization and many undergo complete metamorphosis.
Option $D$ is correct as they have well-developed sensory organs and a haemocoel.

(B) Millipedes $(Julus)$ and Centipedes $(Scolopendra)$ belong to the class $Myriapoda$ under the phylum $Arthropoda$.
$Myriapoda$ is a subphylum or class characterized by numerous legs and a segmented body.
$Arachnida$ includes spiders and scorpions.
$Scaphopoda$ and $Pelecypoda$ are classes within the phylum $Mollusca$.

(C) Spiders possess specialized organs called spinnerets,located just anterior to the terminal anus.
These spinnerets secrete a liquid protein that hardens into silken threads upon contact with air,which the spider uses to construct its web.

(B) The larva of the mosquito $Culex$ is characterized by a long respiratory siphon at the posterior end of its body. When the larva rests at the water surface,it hangs at an angle,with its respiratory siphon piercing the surface film to breathe air,while its head is directed downwards into the water to feed on microorganisms.

(D) The characteristics mentioned,such as a hard exoskeleton (chitinous),a fused head and thorax (cephalothorax),and gills for respiration,are diagnostic features of the subphylum $Crustacea$.
Members of the class $Crustacea$ (e.g.,prawns,crabs,lobsters) are primarily aquatic and utilize gills for gas exchange.
In contrast,$Insecta$ typically have tracheae,and $Myriapoda$ (like centipedes) also use tracheal systems.