Morphology of Cockroach Questions in English

(C) In cockroaches,there are $10$ pairs of spiracles in total.
$2$ pairs of spiracles are located in the thoracic region (one pair in the mesothorax and one pair in the metathorax).
$8$ pairs of spiracles are located in the abdominal region (one pair on each of the first $8$ abdominal segments).
Therefore,the correct distribution is $2$ pairs in the thorax and $8$ pairs in the abdomen.

(B) The process of development of a cockroach from the nymph stage to the adult stage is known as $Metamorphosis$.
Cockroaches undergo $paurometabolous$ development,meaning that development is through the nymphal stage.
The nymphs look very much like adults and undergo $13$ moults before reaching the adult form.

(A) The compound eyes of a cockroach consist of several ommatidia,which are the units of vision.
These eyes form an image known as mosaic vision or apposition image.
In this type of vision,each ommatidium receives only a small part of the object,and the final image is formed by the combination of these parts.
Cockroaches do not exhibit superposition vision,which is typically found in some nocturnal insects.

(B) The cockroach belongs to the Phylum $Arthropoda$ and the Class $Insecta$.
$Arthropoda$ is the phylum,while $Insecta$ is the specific class within that phylum to which cockroaches belong.

(D) The scientific name $Periplaneta$ $americana$ refers to the American cockroach.
Cockroaches belong to the class $Insecta$ and the order $Blattodea$.
Since $Blattodea$ is not listed among the given options,the correct choice is $D$.

(D) Each compound eye of a cockroach is composed of approximately $2000$ visual units called ommatidia. These ommatidia act as the functional units of the compound eye,allowing the insect to perceive images.

(B) The mouth parts of a butterfly are modified into a long,coiled tube known as a proboscis.
This structure is specifically adapted for sucking nectar from flowers.
This type of mouth part is known as the siphoning type.
Therefore,the correct option is $B$.

(C) The cockroach is an omnivorous organism. It feeds on all types of organic debris,including plant matter,animal remains,and household waste.

(A) Johnston's organ is a chordotonal sensory organ located within the second segment (pedicel) of the antennae in insects.
In male mosquitoes,this organ is highly developed and functions as an auditory receptor,which helps them to locate females by detecting the frequency of their wing beats (flight tone).

(B) In mosquitoes and houseflies,halteres develop from the $Metathorax$.
These are modified hindwings that act as balancing organs during flight and also function as sensory organs to receive sound stimuli.

(C) The mouthparts of a $Cockroach$ $(Periplaneta \text{ } americana)$ are adapted for feeding on solid food.
These mouthparts consist of a labrum (upper lip),a pair of mandibles,a pair of maxillae,a labium (lower lip),and a hypopharynx (tongue).
The mandibles are strong,hard,and possess teeth-like structures used for cutting and grinding food.
Therefore,the mouthparts of a $Cockroach$ are classified as the $Cutting \text{ } and \text{ } biting$ type.

(A) In $Blatta \text{ } orientalis$ (the Oriental cockroach), the wings are vestigial in females, while they are well-developed in males.
In $Periplaneta \text{ } americana$ (the American cockroach), both males and females have fully developed wings that extend beyond the tip of the abdomen.

(A) In cockroaches,a pair of jointed,filamentous structures called anal cerci are present on the $10^{th}$ abdominal segment in both males and females.
These structures are sensory in nature and help in detecting vibrations in the environment.

(C) The housefly undergoes complete metamorphosis (holometabolous development).
The life cycle consists of four distinct stages:
$1$. Egg: The female lays eggs in decaying organic matter.
$2$. Larva (Maggot): The egg hatches into a legless larva.
$3$. Pupa: The larva transforms into a pupa within a protective casing.
$4$. Imago (Adult): The final stage where the adult fly emerges from the pupa.
Therefore,the correct order is $Egg \rightarrow Larva \rightarrow Pupa \rightarrow Adult$.

(A) Cockroaches are unisexual and exhibit sexual dimorphism.
In males,the $9^{th}$ abdominal segment bears a pair of short,thread-like anal styles ventrally,which are absent in females.
Anal cerci are present in both sexes,so they cannot be used to distinguish between them.
Therefore,the presence of anal styles is a key external feature to distinguish males from females.

(D) $Periplaneta$ (cockroach) exhibits paurometabolous development,which is a type of incomplete metamorphosis. In this process,the development is direct,and the young ones,called nymphs,resemble the adults. This is also referred to as gradual metamorphosis,as the nymphs grow by moulting (ecdysis) to reach the adult stage.

(A) The cockroach possesses an exoskeleton made of chitinous plates called sclerites.
In the head region,the internal skeletal structures are formed by the invagination of the exoskeleton,which provides attachment points for muscles.
These internal structures are collectively referred to as the endoskeleton (or tentorium) of the head.
Therefore,the head of the cockroach contains both an exoskeleton and an endoskeleton.

(A) The thorax of a $Cockroach$ consists of three segments: $Prothorax$,$Mesothorax$,and $Metathorax$.
$Cockroach$ has two pairs of wings.
The first pair of wings arises from the $Mesothorax$ and is known as $Tegmina$ or $Elytra$,which are thick,hard,and leathery.
The second pair of wings arises from the $Metathorax$ and is thin,soft,and membranous.
Since wings are attached to the $Mesothorax$ and $Metathorax$,they are absent from the $Prothorax$.

(A) Male cockroaches can be distinguished from female cockroaches by the presence of a pair of thread-like anal styles,which are absent in females.
Additionally,the abdomen of the male is narrower and longer,whereas the abdomen of the female is broader and shorter.
Therefore,the presence of anal styles is a primary diagnostic feature.

(A) In $Periplaneta$,wings are well-developed in both sexes. In $Blatta$ (specifically the female),the tegmina (forewings) are very short and the hind wings are absent,resulting in reduced wings compared to $Periplaneta$.

(C) The leg of a cockroach consists of five segments or podomeres,which are arranged from the body outward as follows: $Coxa$,$Trochanter$,$Femur$,$Tibia$,and $Tarsus$.
Among these,the $Tibia$ is the longest segment of the leg.

(B) In butterflies,the mouthparts are modified into a long,coiled,tube-like structure known as the proboscis,which is used for siphoning nectar from flowers.
This proboscis is formed by the elongation of the $galea$ of the $maxillae$.

(A) The proboscis of a housefly consists of three parts: the rostrum,the haustellum,and the labella. The labella are two oval,fleshy lobes at the distal end of the proboscis. These lobes are traversed by a series of fine,semi-circular channels known as pseudotracheae,which resemble the tracheae of insects in appearance and function to collect liquid food.

(D) The antennae of a $Cockroach$ are sensory organs that bear both tactile (touch) and olfactory (smell) receptors.
These receptors allow the $Cockroach$ to sense its environment,detect food,and identify potential mates or predators through touch and chemical signals in the air.

(B) The ootheca of a cockroach is a dark reddish to blackish brown capsule,about $8-10 \text{ mm}$ long.
Each ootheca contains $16$ fertilized eggs arranged in two rows.

(A) Holometaboly,or complete metamorphosis,involves four distinct developmental stages: egg,larva,pupa,and adult.
In this process,the larva is morphologically and ecologically very different from the adult.
Among the given options,the Lady Bird Beetle $(Coccinella)$ undergoes complete metamorphosis (holometaboly).
Bed bugs,cockroaches,and grasshoppers undergo hemimetaboly or paurometaboly (incomplete metamorphosis),where the young stages (nymphs) resemble the adults.

(B) In the case of gradual metamorphosis,the newly hatched creature (nymph) resembles the adult in general body form,but it lacks wings and external genital appendages. This type of development is known as paurometabolous development.

(B) The mouthparts of a housefly $(Musca \text{ } domestica)$ are of the sponging and sucking type.
These mouthparts are specifically adapted to feed on liquid or semi-liquid food sources by sponging up the material.

(C) The leg of a cockroach consists of five segments. Starting from the base towards the distal end,these segments are: $Coxa$,$Trochanter$,$Femur$,$Tibia$,and $Tarsus$.
$Fibula$ is a bone found in the hindlimb of vertebrates (specifically in the lower leg),not in the leg of an insect like a cockroach.

(C) In mosquitoes,the metathoracic or hind wings are modified into $Halteres$. These are small,club-shaped structures that act as sensory organs for balance during flight and are also involved in sound production.

(B) The correct matching is as follows:
$1$. $A$. Ommatidia: These are the visual units of the compound eye in insects,used for vision $(i)$.
$2$. $B$. Trochanter: This is a small segment of the insect leg that is fused with the large and stout femur $(ii)$.
$3$. $C$. Coxa: This is the basal segment of the insect leg that provides articulation with the thorax $(iii)$.
$4$. $D$. Sclerites: These are the hardened plates of the insect's body wall that form the exoskeleton $(iv)$.
Therefore,the correct combination is $A-i, B-ii, C-iii, D-iv$.

(B) . Arthropods possess compound eyes. Each compound eye is composed of numerous independent visual units called ommatidia. These structures are responsible for photoreception in insects like the cockroach.

(A) The mouth parts of mosquitoes are adapted for piercing the skin of the host and sucking blood. Female mosquitoes possess specialized mouth parts for piercing and sucking,while male mosquitoes primarily feed on nectar using a modified sucking mechanism. Therefore,the most accurate description for the mosquito's feeding apparatus is the piercing and sucking type.

(D) In cockroaches,the compound eyes consist of several independent visual units called ommatidia. Each ommatidium forms a separate image of a part of the object. These multiple images combine to form a composite image,which is known as mosaic vision. Since the pigment sheath of the ommatidia is non-contractile,the cockroach is capable of only mosaic vision,even during the night.

(B) The body of an adult cockroach is divided into three distinct regions: head,thorax,and abdomen.
The head is formed by the fusion of $6$ segments.
The thorax consists of $3$ segments (prothorax,mesothorax,and metathorax).
The abdomen of an adult cockroach consists of $10$ segments.
Therefore,the total number of segments in the abdomen is $10$.

(A) The peculiar pungent smell of a cockroach is produced by the secretions of pheromones.
These pheromones are chemical substances secreted by the cockroach that elicit specific physiological or behavioral responses in other members of the same species.
They are primarily used for communication,such as attracting mates or marking trails.
Flame cells are excretory organs in Platyhelminthes,not cockroaches.
Abdominal and cervical glands are not the primary source of the characteristic pungent odor associated with cockroaches.

(C) The genus $Blatta$ includes the species $Blatta$ $orientalis$,which is commonly known as the Oriental cockroach.
In contrast,the German cockroach is $Blattella$ $germanica$,the American cockroach is $Periplaneta$ $americana$,and the Australian cockroach is $Periplaneta$ $australasiae$.

(B) In a cockroach,the newly hatched young one is called a nymph.
It resembles the adult in its general structure but lacks wings and mature reproductive organs.
The development of a cockroach is paurometabolous,meaning the nymph undergoes several moulting stages to reach the adult form.

(D) The legs of a cockroach consist of five segments: coxa,trochanter,femur,tibia,and tarsus.
The tarsus is further divided into five segments called tarsomeres.
The adhesive pads present on the ventral surface of the tarsomeres are known as $Plantulae$ (or $arolia$ in some contexts).
These pads help the cockroach in climbing smooth surfaces.

(A) In the male cockroach,the posterior end of the abdomen shows specific structures:
$1$. The $10^{th}$ tergum is the dorsal plate at the end of the abdomen (labeled $c$ in the diagram).
$2$. The anal cerci are paired,jointed,filamentous structures present on the $10^{th}$ segment (labeled $b$).
$3$. The anal styles are a pair of short,thread-like structures present only in males on the $9^{th}$ sternum (labeled $d$).
$4$. The $8^{th}$ sternum is the ventral plate (labeled $a$).
Therefore,the correct labeling is $a-8^{th}$ sternum,$b-$ anal cercus,$c-10^{th}$ tergum,$d-$ anal style.

(C) The blood of a cockroach is colourless because it lacks the respiratory pigment hemoglobin.
It is known as hemolymph.
In contrast,earthworms and leeches have hemoglobin dissolved in their plasma,giving their blood a red colour,and frogs have red blood due to hemoglobin present in their red blood cells.

(B) In cockroaches,sexual dimorphism is observed.
Male cockroaches possess a pair of thread-like anal styles on the $9^{th}$ abdominal segment,which are absent in females.
Anal cerci are present in both male and female cockroaches.
Therefore,the presence of anal styles is the key morphological feature used to distinguish males from females.

(A) Complete metamorphosis (holometabolism) involves four distinct stages in the life cycle: egg,larva,pupa,and adult.
Both the house fly ($Musca$ $domestica$) and the mosquito ($Anopheles$ or $Culex$) undergo complete metamorphosis.
In contrast,the cockroach undergoes incomplete metamorphosis (hemimetabolism),where the life cycle consists of egg,nymph,and adult stages,lacking a pupal stage.
Therefore,the correct answer is house fly and mosquito.

(A) The leg of a cockroach consists of five segments: the basal flat $Coxa$,a small $Trochanter$,a long $Femur$,a slender spiny $Tibia$,and the foot or $Tarsus$. The $Fibula$ is a bone found in the lower leg of vertebrates (like humans) and is absent in the leg segments of a cockroach.

(C) The compound eye of a cockroach consists of approximately $2000$ hexagonal units called ommatidia.
Each ommatidium acts as an independent visual unit responsible for photoreception.
Therefore,the ommatidium is the structural and functional unit of the compound eye in insects.

(D) The egg of a cockroach is of the $Centrolecithal$ type.
In this type of egg,the yolk is concentrated in the central part of the cytoplasm,while the active cytoplasm is restricted to the periphery.
Therefore,the correct option is $D$.

(B) Complete metamorphosis (also known as holometabolism) involves four distinct stages in the life cycle of an insect: egg $\rightarrow$ larva $\rightarrow$ pupa $\rightarrow$ adult (imago).
In this process,the larva is structurally and functionally very different from the adult.

(D) The mouthparts of insects are adapted according to their feeding habits.
$1$. Cockroaches have biting and chewing type mouthparts.
$2$. Houseflies have sponging type mouthparts.
$3$. Butterflies have siphoning type mouthparts.
$4$. Mosquitoes have piercing and sucking type mouthparts,which allow them to penetrate the skin of their host and suck blood.

(A) The compound eye of an insect is composed of several independent visual units called $Ommatidia$ (singular: $Ommatidium$).
Each $Ommatidium$ acts as a separate photoreceptor unit that captures light and forms a part of the overall image.
Therefore,the correct answer is $Ommatidium$.

(A) Cockroaches are $Omnivorous$ organisms.
They feed on a wide variety of organic matter, including plant materials, decaying organic matter, and even small insects or food scraps found in human environments.
Therefore, they are classified as $Omnivores$.