Morphology of Cockroach Questions in English

(B) In cockroaches,the $Thorax$ region is the most well-developed part regarding both the exoskeleton and the endoskeleton.
The exoskeleton of the thorax consists of hardened plates called $Sclerites$ (terga,sterna,and pleura).
The endoskeleton of the thorax is also highly developed to provide attachment points for the powerful muscles required for locomotion,specifically for the movement of wings and legs.

(C) In cockroaches,sexual dimorphism is present.
Male cockroaches can be distinguished from female cockroaches by the presence of a pair of short,thread-like anal styles.
Anal styles are present only in male cockroaches and are absent in female cockroaches.
Both sexes possess anal cerci,so they cannot be used for differentiation.

(C) The exoskeleton of cockroaches and other insects is primarily composed of a tough,protective polysaccharide called $Chitin$.
$Chitin$ is a nitrogen-containing polysaccharide that provides structural support and protection to the insect body.
It is secreted by the epidermal cells and forms the hard plates known as sclerites.

(D) In a cockroach $(Periplaneta \ americana)$, the respiratory system consists of a network of trachea that open through $10$ pairs of small holes called spiracles present on the lateral side of the body.
These $10$ pairs are distributed as follows:
$2$ pairs are located in the thoracic region.
$8$ pairs are located in the abdominal region.
Therefore, the total number of spiracles is $10$ pairs.

(D) In a cockroach, the egg is $Centrolecithal$.
In $Centrolecithal$ eggs, the yolk is concentrated in the center of the egg, while the cytoplasm is restricted to the periphery.
This type of egg is characteristic of many insects, including the cockroach $(Periplaneta \text{ } americana)$.

(C) In cockroaches,the $10^{th}$ abdominal segment bears a pair of jointed filamentous structures called anal cerci in both sexes. However,male cockroaches possess an additional pair of short,thread-like anal styles,which are absent in females. Therefore,anal styles are a characteristic feature used to distinguish male cockroaches from females.

(C) Insects,such as the cockroach,possess compound eyes. Each compound eye consists of several independent visual units called ommatidia. Through these ommatidia,an insect can receive several images of an object,which is known as mosaic vision.

(A) In both male and female cockroaches,the abdomen consists of $10$ segments.
However,there are morphological differences in the structure of these segments.
In males,the $9^{th}$ sternum bears a pair of short,thread-like anal styles,which are absent in females.
Therefore,both sexes possess $10$ abdominal segments.

(C) Stink glands (also known as odor glands) are specialized exocrine glands found in cockroaches (specifically $Periplaneta$ $americana$). These glands are located on the $6^{th}$ abdominal tergum. They are present in both male and female cockroaches and are used for defense by secreting a foul-smelling fluid to deter predators.

(D) The development of the cockroach is paurometabolous,meaning it involves nymphal stages that resemble the adult.
These nymphs grow by molting.
The nymphal stage undergoes molting $13$ times to reach the adult form.
Therefore,the number of molts is $13$,which falls into the category of 'More than $10$'.

(C) In cockroaches $(Periplaneta \text{ } americana)$, the female produces egg cases called oothecae.
Each ootheca is a dark reddish to blackish brown capsule, about $8 \text{ } mm$ long.
These oothecae are dropped or glued to a suitable surface, usually in a crack or crevice of high relative humidity near a food source.
On average, each ootheca contains $14-16$ fertilized eggs.

(B) In a cockroach $(Periplaneta \text{ } americana)$, the legs (appendages) are attached to the thoracic segments. Each leg consists of $5$ segments: $1$. Coxa, $2$. Trochanter, $3$. Femur, $4$. Tibia, and $5$. Tarsus. The tarsus is further subdivided into $5$ tarsomeres. Therefore, the total number of segments in the leg of a cockroach is $5$.

(D) In cockroaches,there are two pairs of wings. The forewings (tegmina) are opaque,dark,and leathery,which cover the hindwings when at rest. Their primary function is to provide protection to the delicate hindwings and the dorsal part of the body. The hindwings are transparent,membranous,and are used for flight. Therefore,the primary function of the wings (specifically the forewings) is protection.

(B) In the context of the cockroach ($Periplaneta$ $americana$),the female cockroach possesses vestigial wings that do not extend beyond the tip of the abdomen. In contrast,the male cockroach has wings that extend beyond the tip of the abdomen. Therefore,the female cockroach is the correct answer.

(B) In a female cockroach,the abdomen consists of $10$ segments.
In females,the $7^{th}$ sternum is boat-shaped and together with the $8^{th}$ and $9^{th}$ sterna forms a brood or genital pouch.
Although there are $10$ abdominal segments,the sternites are visible as $7$ in females because the $8^{th}$ and $9^{th}$ sterna are modified to form the genital pouch and are not externally visible as distinct segments in the same way as the preceding ones.
Therefore,the number of visible sternites in the female cockroach abdomen is $7$.

(C) The life cycle of a cockroach is $Paurometabolous$ (gradual metamorphosis).
This means that the development occurs through nymphal stages.
The nymph looks very much like the adult.
The nymph grows by moulting (ecdysis) about $13$ times to reach the adult form.
Therefore,the correct option is $C$.

(B) The scientific name of the common cockroach is $Periplaneta \text{ } americana$.
$Glossina \text{ } palpalis$ is the tsetse fly.
$Musca \text{ } nebulo$ is the housefly.
$Apis \text{ } indica$ is the Indian honey bee.

(C) The mouthparts of a cockroach consist of a labrum (upper lip),a pair of mandibles,a pair of maxillae,a labium (lower lip),and a hypopharynx (tongue). These structures are specifically organized to facilitate biting and chewing of food particles. Therefore,they are classified as biting and chewing type mouthparts.

(A) In the anatomy of a cockroach,the exoskeleton of each body segment consists of hardened plates called sclerites.
These sclerites are the dorsal tergum,the ventral sternum,and the lateral pleura.
The tergum and sternum are joined to each other on the sides by a thin,flexible,and soft chitinous membrane known as the arthrodial membrane (or articular membrane).
This membrane allows for the movement of the body segments.

(C) In the cockroach,the exoskeleton of each segment consists of four hardened plates called sclerites: a dorsal tergum,a ventral sternum,and two lateral pleura.
The outer margin of the dorsal tergum is bent downwards and is joined to the lateral pleuron by a thin,flexible articular membrane (arthrodial membrane).
Therefore,the correct option is $C$.

(C) The genus name $Periplaneta$ for the cockroach was proposed by the German entomologist Hermann Burmeister. Therefore,the correct option is $C$.

(B) In cockroaches,there are two pairs of wings.
The forewings,also known as tegmina,arise from the mesothorax.
The hindwings arise from the metathorax.
Therefore,the tegmina are found on the mesothorax.

(C) The compound eyes of insects, such as the cockroach $(Periplaneta \text{ } americana)$, consist of several thousand hexagonal units called ommatidia. Each ommatidium functions as an independent visual unit, allowing the insect to receive several images of an object. This type of vision is known as mosaic vision, which provides high sensitivity but low resolution.

(B) In cockroaches,the $10^{th}$ segment bears a pair of jointed filamentous structures called anal cerci in both sexes. However,male cockroaches possess an additional pair of short,thread-like anal styles,which are absent in females. Therefore,anal styles are a characteristic feature used to distinguish male cockroaches from females.

(A) The head of a cockroach is formed by the fusion of six segments and shows great mobility in all directions due to a flexible neck. Based on the position of the head,which is oriented at a right angle to the longitudinal body axis and points downwards,the cockroach is known as $Hypognathous$.

(A) The mouthparts of a cockroach consist of a labrum,a pair of mandibles,a pair of maxillae,a labium,and a hypopharynx.
Each mandible is a hard,chitinous structure that is triangular in shape.
These mandibles are located on the lateral sides of the mouth.
They possess strong,tooth-like structures (incisor and molar areas) that are used for grinding and crushing food particles.
Therefore,the correct description is that they are small and possess grinding teeth.

(A) Cockroaches possess compound eyes,which are situated at the dorsal side of the head.
Each eye consists of about $2000$ hexagonal ommatidia.
With the help of several ommatidia,a cockroach can receive several images of an object.
This kind of vision is known as mosaic vision with more sensitivity but less resolution,being common during the night (nocturnal vision).

(C) Cockroaches are $Omnivorous$ in their feeding habits. They feed on a wide variety of organic matter, including plant materials, decaying organic matter, household waste, and even small insects. Because they consume both plant and animal-derived materials, they are classified as $Omnivorous$.

(A) In a cockroach,the exoskeleton of each abdominal segment consists of hardened plates called sclerites.
These sclerites are joined to each other by a thin and flexible articular membrane (arthrodial membrane).
The dorsal sclerite is called the $Tergum$,the ventral sclerite is called the $Sternum$,and the lateral sclerites are called $Pleurites$ (or $Pleura$).
Therefore,the dorsal sclerite of the abdominal segment is known as the $Tergum$.

(A) The development of the cockroach $(Periplaneta \text{ } americana)$ is paurometabolous,meaning development occurs through the nymphal stage.
The nymph grows by molting (ecdysis).
The nymphal stage undergoes molting $13$ times to reach the adult form.
Therefore,the correct answer is $13$ times.

(C) In a cockroach $(Periplaneta \text{ } americana)$, the thorax consists of three segments: prothorax, mesothorax, and metathorax. Each thoracic segment bears a pair of walking legs, totaling three pairs ($6$ legs). These legs are specialized for locomotion, allowing the cockroach to walk, run, and climb surfaces efficiently. Therefore, the correct option is $C$.

(A) The lifespan of a cockroach depends on the species and environmental conditions. For the common American cockroach ($Periplaneta$ $americana$),the lifespan is typically about $1$ year,although it can vary based on temperature and humidity. Other species may have different lifespans,but $1$ year is the standard biological reference for the common cockroach in textbooks.

(A) Cockroaches are $nocturnal$ (active at night) and $omnivorous$ (feeding on both plant and animal matter) insects. They are commonly found in damp places and are known to be pests in human dwellings.

(D) The body of a cockroach $(Periplaneta \text{ } americana)$ is distinctly segmented and jointed. The body is divided into three regions: head, thorax, and abdomen. The exoskeleton is made of chitinous plates called sclerites, which are joined by articular membranes. This segmentation is a characteristic feature of the phylum Arthropoda.

(C) The genus $Blatta$ refers to the species $Blatta$ $orientalis$,which is commonly known as the Oriental cockroach.
- $Blattella$ $germanica$ is known as the German cockroach.
- $Periplaneta$ $americana$ is known as the American cockroach.
- $Periplaneta$ $australasiae$ is known as the Australian cockroach.
Therefore,the correct option is $C$.

(D) The mouthparts of a cockroach consist of a labrum (upper lip),a pair of mandibles,a pair of maxillae,and a labium (lower lip).
$1$. The labrum is the upper lip.
$2$. The mandibles are the biting and cutting structures.
$3$. The maxillae are the accessory feeding structures.
$4$. The labium is the lower lip,which is also known as the $adho-oshtha$ in biological terminology.
Therefore,the correct option is $D$.

(B) In cockroaches,sexual attraction is mediated by chemical signals known as pheromones.
These chemical substances are secreted by the endocrine glands and released into the environment to attract members of the opposite sex for mating.
$A$ is incorrect because ecdysone is a molting hormone.
$C$ is incorrect because the juvenile hormone regulates development and metamorphosis.
$D$ is incorrect because anal cerci are sensory organs used for detecting vibrations and wind currents.

(A) In cockroaches,sexual dimorphism is clearly visible.
$1$. Male cockroaches possess a pair of thread-like anal styles,which are absent in females.
$2$. Both sexes possess a pair of jointed filamentous structures called anal cerci at the $10^{th}$ segment.
$3$. Therefore,the presence of anal styles is the primary morphological feature used to distinguish males from females.

(B) In cockroaches,the stink glands (also known as odoriferous glands) are specialized structures located on the dorsal side of the abdomen. These glands are specifically situated between the $5^{th}$ and $6^{th}$ terga (dorsal plates). They secrete a foul-smelling fluid that serves as a defense mechanism against predators. Therefore,the correct option is $B$.

(D) Sexual dimorphism refers to the distinct morphological differences between the male and female individuals of the same species.
In $Cockroach$ $(Periplaneta \text{ } americana)$, sexual dimorphism is clearly visible.
Male cockroaches have long, thread-like anal styles, which are absent in females.
Additionally, males are generally smaller than females and have longer wings that extend beyond the tip of the abdomen.
$Hydra$, $Earthworm$, and $Sponge$ are generally hermaphroditic (bisexual) and do not exhibit distinct sexual dimorphism.

(C) The leg of a cockroach consists of five segments: $Coxa$,$Trochanter$,$Femur$,$Tibia$,and $Tarsus$.
$Coxa$ is the basal segment that attaches to the thorax.
$Trochanter$ is a small segment.
$Femur$ is the third and the largest,most swollen segment of the leg.
$Tibia$ is a long,slender segment.
$Tarsus$ is the distal part consisting of five tarsomeres.
Therefore,the most swollen part is the $Femur$.

(B) In $Periplaneta$ $americana$ (cockroach),the mouthparts consist of a labrum (upper lip),a pair of mandibles,a pair of maxillae,and a labium (lower lip).
There is a median flexible lobe acting as a tongue,which lies within the cavity enclosed by the mouthparts.
This structure is known as the $Hypopharynx$.

(D) The antennae of a cockroach are sensory organs that are highly sensitive to the environment.
They contain numerous sensory receptors,specifically tactile (touch) receptors and olfactory (smell) receptors.
These receptors help the cockroach in sensing its surroundings,detecting food,and identifying potential mates or predators.
Therefore,the correct option is $D$.

(B) The life cycle of a cockroach ($Periplaneta$ $americana$) undergoes $Paurometabolous$ development.
This means that the development is gradual,where the nymphs resemble the adults.
The nymph grows by molting (ecdysis) about $13$ times to reach the adult form.
Since the nymphs look very similar to the adults and development is gradual,it is termed $Paurometabolous$ metamorphosis.

(B) The head of a cockroach is formed by the fusion of six segments. The dorsal part of the head is known as the $Vertex$. The $Frons$ is the plate located below the eyes,which forms the anterior part of the cranium. The $Gena$ refers to the cheeks,and the $Clypeus$ is the plate below the $Frons$ to which the labrum is attached. Therefore,the plate below the eyes is the $Frons$.

(C) The compound eye of a cockroach consists of about $2000$ hexagonal units called ommatidia (singular: ommatidium).
Each ommatidium functions as an independent visual unit,allowing the cockroach to receive several images of an object,which is known as mosaic vision.
Therefore,the correct structural unit is the ommatidium.

(C) The development of a cockroach is paurometabolous,meaning that development occurs through the nymphal stage. The nymph looks very much like an adult. The nymph grows by moulting about $13$ times to reach the adult form. The next nymphal stage is referred to as an $Instar$.

(A) In $Periplaneta\ americana$ (American cockroach),both males and females possess well-developed wings that extend beyond the tip of the abdomen.
In contrast,$Blatta\ orientalis$ (Oriental cockroach) exhibits sexual dimorphism regarding wings; the wings are vestigial or reduced in both sexes,and they do not cover the entire abdomen.
Therefore,the primary morphological difference in terms of flight capability and wing structure is that $Periplaneta\ americana$ has well-developed wings compared to $Blatta\ orientalis$.

(A) The thorax of a cockroach consists of three segments: $Prothorax$,$Mesothorax$,and $Metathorax$.
Wings in a cockroach arise from the $Mesothorax$ (forewings or tegmina) and the $Metathorax$ (hindwings).
Therefore,the $Prothorax$ does not bear any wings.

(C) The exoskeleton of a cockroach is hard and is composed of a tough,non-living substance called $Chitin$.
This exoskeleton provides protection to the internal organs and serves as a site for muscle attachment.
It is secreted by the underlying epidermis and is organized into plates called sclerites.