Phylum-Arthropoda Questions in English

(B) $Palaemon$ is commonly known as $Prawn$.
It is an aquatic animal.
It belongs to the class $Crustacea$ of the phylum $Arthropoda$.

(C) The class $Arachnida$ belongs to the phylum $Arthropoda$.
Members of this class are characterized by having four pairs of walking legs and a body divided into two regions: the cephalothorax and the abdomen.
Spiders,scorpions,ticks,and mites are common examples of $Arachnida$.
Wasps,insects,and beetles belong to the class $Insecta$ (or $Hexapoda$),which is characterized by three pairs of legs and a body divided into three regions: head,thorax,and abdomen.
Therefore,the correct option is $C$.

(A) Social insects are those that live in colonies,exhibit division of labor,and show cooperative brood care.
White ants,also known as termites,are classic examples of social insects.
They live in large,highly organized colonies with a caste system consisting of queens,kings,workers,and soldiers.
Therefore,the correct option is $A$.

(B) The thorax of a housefly $(Musca \text{ } domestica)$ is three-segmented and bears three pairs of legs, one pair of functional wings, and a pair of halteres (modified hind wings).
Dragonflies, mayflies, and butterflies possess two pairs of wings.

(D) The body of a tick $(Acarina)$ is not divided into distinct head,thorax,and abdomen regions. Instead,it possesses a specialized structure called the $capitulum$ or $gnathosoma$,which bears the mouthparts,but it lacks a true,independent head region found in insects. In contrast,insects like bed bugs,lice,and butterflies have a distinct,well-defined head.

(D) Antennae are sensory appendages found on the head of most arthropods,particularly insects.
$A$,$B$,and $C$ (Housefly,Mosquito,and Silkworm) are insects belonging to the class $Insecta$,which possess one pair of antennae.
$D$ (Tick) belongs to the class $Arachnida$. Arachnids are characterized by having four pairs of legs and lacking antennae. Therefore,antennae are absent in ticks.

(B) Arthropods are characterized by the presence of a $segmented$ $body$, $jointed$ $appendages$, and an $exoskeleton$ made of $chitin$.
They possess various types of $respiratory$ $organs$ such as $gills$, $book$ $gills$, $book$ $lungs$, or the $tracheal$ $system$.
However, $cilia$ are generally absent in the cells of arthropods, as they rely on other mechanisms for movement and transport.

(B) $Arthropoda$ is differentiated from $Annelida$ primarily by the absence of $nephridia$.
In $Annelida$,$nephridia$ are the specialized excretory organs responsible for osmoregulation and excretion.
In $Arthropoda$,excretion occurs through different structures such as $Malpighian$ tubules,green glands,or coxal glands,and $nephridia$ are completely absent.

(B) $Peripatus$ belongs to the phylum $Onychophora$ (often considered a connecting link between $Annelida$ and $Arthropoda$).
In $Peripatus$,the primary excretory organs are $nephridia$,which are characteristic of annelids,reflecting its evolutionary status.

(A) The class $Crustacea$ belongs to the phylum $Arthropoda$.
Key characteristics of $Crustacea$ include the fusion of the head and thorax into a $Cephalothorax$,the presence of $biramous$ (two-branched) appendages,and respiration primarily through $gills$.
Common examples include prawns,lobsters,and crabs.
Therefore,option $A$ is the correct description.

(D) $Limulus$, commonly known as the king crab, belongs to the sub-class $Xiphosura$ and the class $Merostomata$ within the sub-phylum $Chelicerata$ of the phylum $Arthropoda$.
It is a living representative of very ancient, primitive chelicerates and is therefore referred to as a "living fossil."

(C) The correct answer is $C$.
$Silver$ $fish$ $(Lepisma)$ is a primitive wingless insect that does not undergo metamorphosis.
It belongs to the Phylum $Arthropoda$ and Class $Insecta$.
In contrast,Star fish belongs to Phylum $Echinodermata$,Gold fish belongs to Phylum $Chordata$ (Class $Osteichthyes$),and Cuttle fish belongs to Phylum $Mollusca$.

(B) The exoskeleton of arthropods is lightweight,tough,and composed of a structural polysaccharide known as chitin.
Chitin is a nitrogen-containing polysaccharide that provides protection and support to the organisms belonging to the phylum $Arthropoda$.

(C) Insects belong to the class $Insecta$ (or $Hexapoda$),which are characterized by having $3$ pairs of jointed legs (total $6$ legs).
Crustaceans,such as crabs and lobsters,typically have more than $3$ pairs of appendages (often $5$ or more pairs).
Therefore,the number of appendages is a primary morphological feature used to distinguish between these two groups of arthropods.

(A) Insects belong to the class $Insecta$ (or $Hexapoda$) within the phylum $Arthropoda$.
Key characteristics of insects include having three pairs of jointed legs ($6$ legs) and a body divided into three regions: head,thorax,and abdomen.
$A$. $Moth$ is an insect belonging to the order $Lepidoptera$.
$B$. $Mites$ are $Arachnids$,not insects,as they have $8$ legs.
$C$. $Prawn$ is a $Crustacean$,which is aquatic and has more than $6$ legs.
$D$. $Scorpion$ is an $Arachnid$ with $8$ legs.
Therefore,the correct answer is $Moth$.

(B) Acarology is the branch of zoology that specifically focuses on the study of mites and ticks,which belong to the subclass $Acari$ within the class $Arachnida$.

(C) Crayfish,scientifically known as $Astacus$,belongs to the phylum $Arthropoda$.
Members of this phylum are characterized by having jointed appendages and a chitinous exoskeleton.

(C) Insects belong to the class $Insecta$ (or $Hexapoda$) under the phylum $Arthropoda$.
The defining characteristic of all insects is the presence of three pairs of jointed legs (total of $6$ legs) attached to the thorax.
While many insects have compound eyes and wings,these are not universal; for example,some insects are wingless (apterous) or have reduced eyes.
Therefore,the presence of three pairs of legs is the most consistent and universal feature of insects.

(B) The larvae of beetles (Order: $Coleoptera$) are commonly referred to as $Grubs$.
$Caterpillars$ are the larvae of butterflies and moths (Order: $Lepidoptera$).
$Maggots$ are the larvae of flies (Order: $Diptera$).
$Naiads$ are the aquatic nymph stages of certain insects like dragonflies and mayflies.

(A) Scorpion belongs to the class $Arachnida$ of the phylum $Arthropoda$.
Ticks also belong to the class $Arachnida$.
Crabs and barnacles belong to the class $Crustacea$.
Cockroaches belong to the class $Insecta$.
Therefore,the correct option is $A$.

(D) The correct option is $D$.
In the phylum $Arthropoda$,the class $Insecta$ (or $Insecta$) is characterized by a body distinctly divided into three regions: head,thorax,and abdomen.
In contrast,many other arthropods,such as those in the class $Crustacea$ and $Arachnida$,exhibit fusion of the head and thorax to form a $cephalothorax$.
Therefore,$Insecta$ is the class where the body is clearly divided into these three distinct parts.

(B) Crustaceans belong to the subphylum $Crustacea$ within the phylum $Arthropoda$.
One of the defining characteristics of crustaceans is the presence of two pairs of antennae (antennules and antennae).
In contrast,insects (class $Insecta$) possess only one pair of antennae.
Paired limbs,a chitinous exoskeleton,and bilateral symmetry are common features shared by both crustaceans and insects as they are both members of the phylum $Arthropoda$.

(B) Insects belong to the class $Insecta$ (or $Hexapoda$) of the phylum $Arthropoda$. The defining characteristic of insects is the presence of $3$ pairs of jointed legs (total $6$ legs) attached to the thorax region of their body.

(C) Silverfish (insect),scorpion (arachnid),dragonfly (insect),and prawn (crustacean) all belong to the phylum $Arthropoda$.
The defining characteristics of all arthropods include the presence of jointed appendages and a chitinous exoskeleton,which provides protection and support.
Option $A$ is incorrect because scorpions and prawns do not have three pairs of legs.
Option $B$ is incorrect because insects have one pair of antennae,while arachnids have none.
Option $D$ is incorrect because insects do not have a cephalothorax (they have a distinct head,thorax,and abdomen).

(A) Most arthropods are oviparous (egg-laying). However,scorpions are notable for being viviparous (giving birth to live young). The female scorpion retains the eggs within her body until they hatch,and the young nymphs are born alive. Therefore,the scorpion is the correct answer as it is not oviparous.

(D) $Limulus$,commonly known as the king crab or horseshoe crab,is widely regarded as a living fossil.
It belongs to the class $Merostomata$ and has remained morphologically unchanged for over $400$ million years.
While $Nautilus$ and $Neopilina$ are also considered living fossils,$Limulus$ is frequently cited in biological literature as the most prominent example of a living fossil due to its extreme evolutionary stasis.

(B) The defining characteristic of the phylum $Arthropoda$ is the presence of jointed appendages ($arthros$ = joint,$poda$ = appendages). While triploblastic,coelomate,and segmented body organization are features of arthropods,these are also found in other phyla like $Annelida$ (segmented,coelomate) or $Chordata$. Therefore,to specifically identify an animal as an arthropod,the presence of jointed appendages is the most critical diagnostic feature that must be verified.

(D) $Myriapoda$ is a subphylum of $Arthropoda$ that includes centipedes and millipedes.
Key characteristics of $Myriapoda$ include:
$1$. $A$ hard $chitinous$ $exoskeleton$ which provides protection and prevents desiccation.
$2$. $A$ $ventral$ $nerve$ $cord$,which is a characteristic feature of all arthropods.
$3$. $A$ body divided into numerous segments (metamerism),unlike insects which have three distinct body segments.
$4$. They possess one pair of $antennae$ on the head.
Therefore,option $D$ is the correct description.

(D) The tracheate group in the phylum $Arthropoda$ consists of organisms that respire through a tracheal system.
$Bedbug$,$Sandfly$,and $Silkworm$ are all insects that utilize a tracheal system for gas exchange.
$Crabs$ and $King$ $crabs$ are aquatic and respire through gills or book gills.
$Scorpions$ and $Spiders$ are arachnids that respire through book lungs.
Therefore,the correct group is $Bedbug$,$Sandfly$,and $Silkworm$.

(D) Haemocyanin is a copper-containing respiratory pigment.
It is found in the blood of Prawns (Arthropoda).
Haemocyanin appears blue when oxygenated and becomes colourless when deoxygenated.

(C) In an open circulatory system,blood is pumped out of the heart into blood spaces or sinuses,and the tissues and organs are bathed in it.
This type of system is characteristic of arthropods and molluscs.
Among the given options,$Prawn$ is an arthropod (crustacean),which possesses an open circulatory system.
Man,Fish,and Snake are vertebrates and possess a closed circulatory system where blood flows through a network of vessels.

(C) In $Centrolecithal$ eggs,the yolk is concentrated in the centre of the ovum,while the cytoplasm is restricted to the peripheral layer.
This type of egg is commonly observed in insects (Arthropoda).

(C) $Limulus$,commonly known as the King Crab,is considered a living fossil.
Living fossils are organisms that have remained essentially unchanged over millions of years and have no close living relatives.
$Limulus$ belongs to the phylum $Arthropoda$ and class $Merostomata$.
It has survived since the Paleozoic era,making it a classic example of a living fossil.

(D) $Peripatus$ acts as a connecting link between $Annelida$ and $Arthropoda$.
It exhibits $Annelidan$ characters such as continuous muscle layers in the body wall,unjointed leg-like parapodia,nephridia for excretion,and a simple gut.
It also exhibits $Arthropodan$ characters such as claws on the legs,a haemocoel,tracheae for respiration,and a dorsal heart with ostia.

(A) $Bombyx \ mori$ (silkworm) belongs to the class $Insecta$ of the phylum $Arthropoda$.
Members of the class $Insecta$ are characterized by having three pairs of jointed legs and a body divided into head,thorax,and abdomen.
Although $Bombyx \ mori$ is an insect,the adult female is flightless due to its heavy body weight and reduced wings.

(C) Swarming is a phenomenon commonly observed in locusts ($Schistocerca$ $gregaria$).
Locusts are migratory grasshoppers that form massive swarms when they undergo a phase change from solitary to gregarious behavior.
These swarms can travel long distances and cause significant damage to crops and vegetation.
Therefore,the correct option is $C$.

(B) Colonial insects are those that live in organized societies or colonies,exhibiting social behavior such as division of labor.
White ants,commonly known as termites,are classic examples of colonial insects.
They live in large colonies with a complex social structure consisting of different castes like the queen,king,workers,and soldiers.
Locusts are gregarious but not strictly colonial in the same social sense as termites.
Bed bugs and mosquitoes are solitary insects and do not form colonies.

(B) Scorpions are $Ovoviviparous$. In $Ovoviviparous$ animals,the embryos develop inside eggs that are retained within the mother's body until they are ready to hatch. The mother provides protection and sometimes nutrients,but the embryos are primarily nourished by the yolk within the egg,rather than directly from the mother's blood supply via a placenta.

(C) The correct answer is $C$ (Spider).
$A$ (Butterfly),$B$ (Honeybee),and $D$ (Beetle) all belong to the class $Insecta$ (phylum $Arthropoda$),which are characterized by having $3$ pairs of jointed legs (total $6$ legs) and a body divided into head,thorax,and abdomen.
$C$ (Spider) belongs to the class $Arachnida$ (phylum $Arthropoda$),which are characterized by having $4$ pairs of jointed legs (total $8$ legs) and a body divided into cephalothorax and abdomen.

(A) The phylum $Arthropoda$ is the largest phylum in the animal kingdom.
It includes insects,arachnids,myriapods,and crustaceans.
Approximately two-thirds of all named species on Earth are arthropods.
Therefore,the correct option is $A$.

(C) Insects (Class $Insecta$) typically possess $3$ pairs of jointed legs (total $6$ legs),whereas crustaceans (Subphylum $Crustacea$) typically possess $5$ or more pairs of jointed legs. Therefore,the number of appendages is the primary morphological characteristic used to distinguish between these two groups within the Phylum $Arthropoda$.

(C) Crabs and prawns belong to the class $Crustacea$ under the phylum $Arthropoda$.
$Crustaceans$ are primarily aquatic organisms characterized by having two pairs of antennae,a hard exoskeleton,and biramous appendages.
In contrast,$Insecta$ includes insects,$Arachnida$ includes spiders and scorpions,and $Diplopoda$ includes millipedes.

(A) Insects belong to the class $Insecta$ under the phylum $Arthropoda$. The defining characteristics of insects include having three pairs of jointed legs (six legs) and a body divided into three regions: head,thorax,and abdomen.
Ticks belong to the class $Arachnida$. Unlike insects,ticks have four pairs of legs (eight legs) and their body is divided into two regions: cephalothorax and abdomen.
Therefore,a tick is not an insect.

(C) In the phylum $Arthropoda$, respiration is diverse due to the wide variety of habitats occupied by these organisms.
$1$. Terrestrial arthropods, such as insects, respire through a system of air tubes called $Trachea$.
$2$. Aquatic arthropods, such as crustaceans (e.g., prawns), respire through $Gills$ or $Book \, gills$.
Since both structures are used for respiration within the phylum $Arthropoda$, the correct answer is $Both$.

(C) Insects belong to the phylum $Arthropoda$ and class $Insecta$. The characteristic features of adult insects include:
$1$. Three pairs of jointed legs (total $6$ legs).
$2$. One pair of antennae.
$3$. Usually two pairs of wings (total $4$ wings),although some insects may have only one pair or be wingless.
Therefore,the most accurate description for the majority of adult insects is that they possess $6$ legs,two antennae,and two or four wings.

(B) Spiders belong to the class $Arachnida$ within the phylum $Arthropoda$.
Unlike insects,which have $3$ pairs of legs,spiders possess $4$ pairs of walking legs,totaling $8$ legs.
Therefore,the correct answer is $4$ pairs.

(D) Green glands,also known as antennary glands,are specialized excretory organs found in the class $Crustacea$ (a subphylum of $Arthropoda$). These glands are located in the head region near the antennae and are responsible for the filtration and excretion of nitrogenous wastes,primarily ammonia,in aquatic crustaceans like prawns and crabs.

(C) Book lungs are specialized respiratory organs found in members of the class $Arachnida$ (e.g.,spiders and scorpions).
These organs consist of a series of thin,leaf-like folds of the body wall that are arranged like the pages of a book,which increases the surface area for gas exchange.
In contrast,$Crustacea$ typically use gills,$Insecta$ use a tracheal system,and $Myriapoda$ use tracheae.

(B) The phylum $Arthropoda$ is characterized by having a segmented body,an open circulatory system,and jointed appendages.
However,they do not possess 'jointed jaws' as a defining characteristic.
While some arthropods have specialized mouthparts (like mandibles),the term 'jointed jaws' is not a standard diagnostic feature of the phylum $Arthropoda$ in the way that jointed appendages are.
Therefore,option $B$ is the correct answer.

(C) The phylum $Arthropoda$ is characterized by the presence of an exoskeleton made of a tough,protective substance called chitin. This exoskeleton is known as a chitinous cuticle. It provides structural support,protection,and prevents desiccation in these organisms. Therefore,the correct option is $C$.